TESS is not good for precision astrometry, because it has 21 arcsec pixels and the PSF is highly undersampled. ?So even measurements to sub-pixel accuracy only get positions down to a few arcsec. ?
?
As far as photometry, TESS is excellent for stationary objects where the background is not changing. ?Unfortunately, comets and asteroids move across the image, frequently crossing in front of stars in the (very crowded) field. ?
?
So to improve the photometry, we need to remove the star background and scattered light, which is difficult, because the PSF is highly undersampled and the scattered light changes with time as the spacecraft orbits the Earth. ? I'm leading one of several groups that are trying to improve the process for solar system objects, and results are getting better, but they often depend on tuning things for the changing conditions. ?For comets, the coma also plays a role, because it interferes with scattered light routines (which see the coma as scattered light). ?In the end, the relative photometric accuracy varies depending on the situation, but for bright comets, it can be better than 0.01 mag.
?
Absolute photometry is less accurate, because the images are pan-chromatic. ?I derived a rough conversion from TESS magnitudes to V and R magnitudes (for comet colors) in ?Farnham, PSJ 2:236 (2021) ?https://doi.org/10.3847/PSJ/ac323d.? ? The conversion is ?V = T+0.8 ?and R = T+0.3, with a systematic uncertainty of ~0.3 mag
?
Tony
?
|
Re: Unusual brightening of comet C/2023 Q1
Hello Juan and all,
I would quote your statement:
"My visual observation of C/2023 Q1 was not a highly difficult
one. I made a clear detection of the very diffuse outer coma."
I would like to clarify that you believe you made a
clear detection. We can either accept this at face value or not,
since there are no other data that would confirm your
observations—except from Thomas, who measured nearly the same coma
diameter but found the comet to be about 2.5 magnitudes fainter.
Here is a practical example: every year during the Perseids, my
friend and I search for faint comets and then show them to others.
There are many comets that I feel certain I can detect clearly,
even though ten other people at the camp see nothing. However, my
friend often confirms what I see. One might argue that experience
matters—the more experienced an observer is, the more they can
see. But if only two people out of many claim a detection, it
might be an “on-the-edge” observation. Another possibility is that
I suggested the comet’s presence to myself (knowing its position)
and subconsciously convinced my friend, while there was in fact
nothing visible.
How do we determine which explanation is correct?
I recall an incident in the 1990s when there was a supposed
outburst reported for some comet—possibly by accident—and, within
a single day, three positive visual observations appeared.
However, it turned out the outburst never happened. Those
observers simply believed they saw a comet that wasn’t there.
I remember another case in which I was personally involved: I
mixed up a comet’s position by a full day during a star party. Yet
everyone there “saw” the comet at the incorrect location,
including three very experienced observers who each had 100+
visual observations under their belt.
Because of experiences like these, I am very cautious when
someone refers to a “clear detection,” since many factors—such as
background gradients in the field of view or varying sensitivity
in different parts of the eye—can complicate visual observations.
Unlike CCD images, visual observations cannot easily be
re-measured by others to confirm what the observer saw.
Another difficulty is that a detection often depends on the
observer’s belief that something is there, and the complex
eye-brain pathway can fool a person. Confirmation is challenging,
even with techniques like tracking the comet’s motion, because
keeping a moving object centered in the field of view can sustain
a gradient or pattern that the observer may interpret as a “faint
outer coma.” Its borders can be unclear and somewhat subjective.
A good approach is to avoid knowing the comet’s precise position
in advance and instead use a larger field, effectively attempting
a “blind” search. This can only be done if the comet has not been
observed in the days before, so the observer’s mind is not biased
by expected positions or appearances. If a “new comet” is drawn on
a map and its coordinates align with the real comet’s position,
that detection can be considered quite robust.
I once had the chance to observe a comet visually from the
Northern Hemisphere while simultaneously obtaining CCD images from
a robotic telescope in the Southern Hemisphere. Comparing these
“blind” visual results with unknown stars and their magnitudes to
the CCD measurements, I found very good agreement. Thus, I can
state my visual observations were truly clear detections on that
occasion—but that does not prove the correctness of any other
observations.
Given the many uncertainties (eye-brain imperfections, suggestion
effects, memory biases, etc.), we must approach visual measures
with healthy skepticism.
What I can say is that Thomas Lehmann makes an exceptional effort
to provide highly reliable total coma magnitudes from CCD data. I
remember attending his lecture on his methods and noticing that
his CCD observations tend to yield some of the brightest
magnitudes and largest coma measurements compared to other
observers. Therefore, I consider his measurements among the best
in the world for confirming (or refuting) borderline visual
detections.
Best regards,
Jakub ?ern?
On 29. 12. 24 21:39, jjgonzalez
jjgonzalez via groups.io wrote:
Denis, Jakub, Bob, friends,
As told previously, I am tired after three consecutive nights (
Dec. 26, 27, 28 ) observing comets from the snowy Cantabrian
Mountains.
So this will be a short reply ...
Denis : Quoting your words :
" ... you previously mentioned you had spoken you last words on
this subject, so it is suprising to hear back from you ..."
My reply was motivated by my obvious disagreement with your
previous comment [ "... in the overall description of the
condition of this comet I would say that that feature ( the
faint outer coma ) ?is a minor component of the comet ... ]
and an implicit general undervaluation of the estimates of the
visual observers with respect to CCD photometry.
Quoting my words : "CCD and visual data are ?complementary, not
exclusive".
Jakub : Being really very tired, and needing a long
recovery sleep, I don't want to have a long and detailed
debate like in the old days, regarding the same issues
comparing visual estimates and CCD measures.
But quoting your words : " Therefore, the reported visual
observation may be in error—either in the estimated magnitude or
the coma diameter. The observer should re-examine their
observation to identify where the discrepancy arose ..."
I must say that both data ( m1, coma diameter ), and the change
in position of the comet, have been verified on two consecutive
nights ( Dec. 27 + 28 ),
Also from your words :
" No one is flawless—myself included."
I obviously agree ...
" ... It has been demonstrated many times that observers can
report objects or details they did not actually see."
My visual observation of C/2023 Q1 was not a highly difficult
one. I made a clear detection of the very diffuse outer coma.
Quoting Bob's words :
" It would be nice if we had some additional visual observers so
there would be a pool of estimates to draw upon. "
These are the words I was hoping to hear, as my initial
contribution to this thread was to provide the input of visual
observers.
And now, really, just before going to sleep, I can seriously say
that this will be my final post on this C/2023 Q1 thread.
Best regards,
J. J. Gonzalez Suarez
P.S.: I wish clear skies and good luck to those visual
observers looking for the very diffuse C/2023 Q1.
-------------------------------------------------------------------------------------------------------------------------------------------------------
On Sun, Dec 29, 2024 at
9:26?PM Denis Buczynski via <buczynski8166= [email protected]>
wrote:
Bob,
It will be intersting to see your report when you are able to
observe
then comet. JJ was observing from a high altitude mountain
site and it
exceptional that he has been able to observe this faint (mag
15 from my
own digital observations)comet. I am not suprised there are no
other
visual reports of this comet, it is faint for visual
observers, but an
relatively easy target for imagers. The feat of visually
observing a
faint outer coma would seem to be difficult in a comet this
faint.
However according to JJ he did indeed acheive this.
Best wishes
Denis
? ? ? ? ------ Original Message ------
? ? ? ? From: nightsky55=[email protected]
? ? ? ? To: [email protected]
? ? ? ? Sent: Sunday, December 29th 2024, 20:09
? ? ? ? Subject: Re: [comets-ml] Unusual brightening of comet
C/2023 Q1
? Jakub and all,
? This discussion has inspired me to observe C/2023 Q1 in my
38-cm
reflector at the next opportunity. I also have a very
? dark sky especially in the north direction — when the aurora
isn't
active! It would be nice if we had some additional visual
observers so
there would be
? a pool of estimates to draw upon. J.J. Gonzalez Suarez's
observation
is the only visual sighting of the comet I'm aware of.
? Bob
? On Sun, Dec 29, 2024 at 1:17?PM Jakub ?ern? via
<kaos=[email protected]>
wrote:
? ? ? ? ? ? ? ? ? ? ? Hello all,
? ? ? ?If I have read the posts correctly, we have two
observations:
? ? ? ?CCD magnitude of 14.1 mag with a 5' aperture.? ? ?
?Visual
magnitude of 11.6 mag with a 6' aperture.? ? ? ? ? How can we
explain
such a large difference? The CCD method? ? ? ?measures flux in
a chosen
aperture, and we know that a comet’s? ? ? ?surface brightness
decreases
with distance from the central? ? ? ?condensation. However,
even if the
surface brightness is? ? ? ?decreasing, the increase in the
area of the
coma can still? ? ? ?significantly change the total measured
magnitude.
? ? ? ?Regarding the well-known “CCD vs. visual” issue, it
often arose
in the past from insufficient exposure times, which led
observers to
measure only the central condensation in a smaller aperture,
whereas
visual observers saw more of the coma. Even among visual
observers
alone, an “aperture effect” has been described—smaller
telescopes can
show a larger apparent coma and thus yield brighter magnitude
estimates.
Hence, the 2–3 mag discrepancy was typically caused by
different coma
sizes captured in visual vs. CCD observations. However, this
problem has
largely faded in recent years as CCD observers have become
more
experienced. With proper techniques, CCD observations now
usually match
visual data closely, differing by only a few tenths of a
magnitude due
to variations in spectral sensitivities (especially for
unfiltered or
narrowband photometry vs. visual V or g' bands).
? ? ? ?It is unlikely that a difference of 2.5 mag could arise
from
nearly the same apertures (5' vs. 6'), because an increase of
just 1' in
aperture should not produce such a large magnitude gap under
normal
circumstances.
? ? ? ?Although it is possible to measure an object as 2.5 mag
brighter
by including a much larger coma with very low surface
brightness (for
example, if the visual observation indicated a coma diameter
of
15'–20'), this is not the situation described here. Therefore,
the
reported visual observation may be in error—either in the
estimated
magnitude or the coma diameter. The observer should re-examine
their
observation to identify where the discrepancy arose.
? ? ? ?No one is flawless—myself included. It has been
demonstrated many
times that observers can report objects or details they did
not actually
see. There have even been cases where a comet was reported at
the wrong
position. We must learn from such instances in order to
provide
scientifically valuable data.
? ? ? ?Best regards,? ? ? ?Jakub ?ern?
|
My estimate of the dynamical age is based on the (inbound) semi-major axis, which is ~4000 au for this comet. Comets with such a semi-major axis of a few thousand au can often become gravitationally unbound from the solar system by planetary perturbations in just a single apparition, where each such passage can randomly deliver a momentum kick up or down depending on exactly when the comet passes through the planetary region. Comets straight from the Oort cloud are essentially right on the edge of being gravitationally bound/unbound originally, so comets like C/2024 G3 are ~1 typical momentum kick in, while an older comet like C/2023 P1 with a semi-major axis of only ~60 au must have passed through the planetary region many, many more times to have received enough of these kicks to shrink its orbit down so much more.
For a proper analysis, you'd need to run a bunch of orbital simulations with clones of this comet on the same orbit, but shifted in perihelion time to measure the probability distribution for the momentum kick expected per apparition. It's quite hard to change the near-perihelion portion of a long period comet's orbit since gravitational perturbations tend to only significantly impact the aphelion distance/orbital period, whereas there aren't any significant perturbation sources stronger than the galactic tide/passing stars, which only really become significant out into the Oort cloud. Therefore, it's reasonably accurate to treat the dynamical evolution process of most long period comets as just random walks starting from the Oort cloud, and you can work out the probability distribution/expected value for the number of apparitions/momentum kicks any comet has had based on the typical kick size and how far the comet is from being unbound. That said, the typical kick size for most cometary orbits through the inner solar system that don't pass particularly close to Jupiter (or any other big planet) tends to be fairly similar. From having just looked at a bunch of these comets, I've found those with semi-major axes of several thousand au, like C/2024 G3, tend to be ~1 kick inward from the Oort cloud, so are statistically likely to have only made one to a few prior passages through the planetary region.
Note also that both old and young comets can be either dust or gas rich, although observational surveys seem to indicate older comets (especially at low q) overall tend to be less dusty than younger comets. Dynamically old comets also do tend to brighten more steadily than new ones, but that's more of a consequence of comets behaving differently on their first time through the inner solar system than afterward, and also because the dynamically new population contains a lot of tiny/unstable comets far smaller than what can survive near the Sun, whereas most of these tiny/unstable comets are destroyed within one apparition, leaving only the large/stable comets and a relatively smaller number of borderline surviving/less stable comets that may or may not survive again in the returning comet population.
Qicheng
On Sunday, December 29, 2024 at 08:41:46 p.m. UTC, Nico Lefaudeux via groups.io <nicolas.lefaudeux@...> wrote:
Hi Qicheng, hi all, i am curious about which information can tell that the comat has "a dynamical age on the order of only ~1 orbit" ? I thought the orbit analysis could only tell the previous aphelion distance, and little about the previous perihelia. Seeing that the comet seems to be very "gas depleted" and almost purely dusty, with a smooth light curve (without steps associated with volatiles "switching on"), i was thinking this was pointing?toward the comet having already seen at least a handful of very close perihelia (or many perihelia at larger distance). i would be glad to learn more about how one can tell if a long-period comet has been near the sun only one or a few times compared to many times. Nicolas
Le?sam. 28 déc. 2024 à?20:06, Qicheng Zhang via <qzalaska= [email protected]> a écrit?:
The comet's absolute magnitude is ~7, so it's technically brighter than the Bortle limit for all q. Of course, it's also dynamically old, but with a dynamical age on the order of only ~1 orbit, and disintegration isn't too abnormal for such comets, even when brighter than the Bortle limit. C/2021 A1 was a recent example that comes to mind. But many also do survive, like C/2002 V1.
A narrow dust spine (at least before perihelion, as in the present case) means there's now considerable dust being released at very low velocity, which requires that dust be from a source far from the nucleus (as outflowing gas would push any dust near the nucleus itself at high velocity into the main coma). That suggests the comet started to disrupt, with fragments breaking off and drifting away from the nucleus before crumbling further into the low velocity, spine-forming dust. This sort of structure is likely also responsible for the triangular shape the gas coma of a disrupting comet often takes, but this comet may be too dusty for its gas coma to be seen.
At the moment, the comet still has a large, primary coma, which indicates there's at least one large, active nucleus present. If the large coma fades out in favor of the spine (which is a distinct possibility, but far from guaranteed at this point), that would signal the end of this nucleus.
Qicheng
On Saturday, December 28, 2024 at 12:29:58 p.m. UTC, Nick James < comets@...> wrote:
Hi all,
I have been observing C/2024 G3 for the last few weeks using T70 at X07
in Chile. This instrument is able to get down to the mountain ridge
horizon which is around 4 degrees at that azimuth and the sky
transparecy at X07 is very good. T70 is a very short FL instrument
(actually a Samyang 135mm FL lens) but it is good for magnitude
estimates of bright comets although the astrometry I get from the images
is a bit ropey.
This morning (Dec 28.35) I had a total magnitude of 6.0 unfiltered using
Comphot and Gaia DR3 G mags. Michael's estiamate at around the same time
using T75 was 5.8 (taken from COBS). These are fitting the lightcurve
well so there is no sign of any abnormal activity at the moment.
Using astrometry from the MPC up to December 23 and my more recent
astrometry with the 135mm lens there appears to be no obvious
improvement to the residuals by including non-gravitational forces. This
was using Findorb.
My image from this morning is here:
Other images and data are here:
Here's hoping that this comet survives to provide a nice display
post-perihelion. Sadly, us northern observers won't get much of a chance
to see it so we will be relying on reports from the southern hemisphere.
Nick James. BAA Comet Section.
On 28/12/2024 07:42, Michael Mattiazzo via wrote:
> Howdy Folks,
>
>?
>
> C/2024 G3 ATLAS has been kept under extensive observation by several observers, despite its poor location.
>
> Attached a light curve showing a steady brightening toward perihelion that could see it reach magnitude -3, if it survives.
>
> I’ve also attached? images from Dec 25 and 26 showing a curious spine feature (often seen in outbursting comets) but this comet is not in outburst.
>
> Hopefully there is sufficient nuclear material to keep going. It is a very dusty comet as seen with the parabolic hood.
>
> This situation reminds me of C/2002 V1 NEAT in March 2023
>
>?
>
> Cheers,
>
> Michael
>
>
>
>
>
>
>
|
Hi Qicheng, hi all, i am curious about which information can tell that the comat has "a dynamical age on the order of only ~1 orbit" ? I thought the orbit analysis could only tell the previous aphelion distance, and little about the previous perihelia. Seeing that the comet seems to be very "gas depleted" and almost purely dusty, with a smooth light curve (without steps associated with volatiles "switching on"), i was thinking this was pointing?toward the comet having already seen at least a handful of very close perihelia (or many perihelia at larger distance). i would be glad to learn more about how one can tell if a long-period comet has been near the sun only one or a few times compared to many times. Nicolas
Le?sam. 28 déc. 2024 à?20:06, Qicheng Zhang via <qzalaska= [email protected]> a écrit?:
The comet's absolute magnitude is ~7, so it's technically brighter than the Bortle limit for all q. Of course, it's also dynamically old, but with a dynamical age on the order of only ~1 orbit, and disintegration isn't too abnormal for such comets, even when brighter than the Bortle limit. C/2021 A1 was a recent example that comes to mind. But many also do survive, like C/2002 V1.
A narrow dust spine (at least before perihelion, as in the present case) means there's now considerable dust being released at very low velocity, which requires that dust be from a source far from the nucleus (as outflowing gas would push any dust near the nucleus itself at high velocity into the main coma). That suggests the comet started to disrupt, with fragments breaking off and drifting away from the nucleus before crumbling further into the low velocity, spine-forming dust. This sort of structure is likely also responsible for the triangular shape the gas coma of a disrupting comet often takes, but this comet may be too dusty for its gas coma to be seen.
At the moment, the comet still has a large, primary coma, which indicates there's at least one large, active nucleus present. If the large coma fades out in favor of the spine (which is a distinct possibility, but far from guaranteed at this point), that would signal the end of this nucleus.
Qicheng
On Saturday, December 28, 2024 at 12:29:58 p.m. UTC, Nick James < comets@...> wrote:
Hi all,
I have been observing C/2024 G3 for the last few weeks using T70 at X07
in Chile. This instrument is able to get down to the mountain ridge
horizon which is around 4 degrees at that azimuth and the sky
transparecy at X07 is very good. T70 is a very short FL instrument
(actually a Samyang 135mm FL lens) but it is good for magnitude
estimates of bright comets although the astrometry I get from the images
is a bit ropey.
This morning (Dec 28.35) I had a total magnitude of 6.0 unfiltered using
Comphot and Gaia DR3 G mags. Michael's estiamate at around the same time
using T75 was 5.8 (taken from COBS). These are fitting the lightcurve
well so there is no sign of any abnormal activity at the moment.
Using astrometry from the MPC up to December 23 and my more recent
astrometry with the 135mm lens there appears to be no obvious
improvement to the residuals by including non-gravitational forces. This
was using Findorb.
My image from this morning is here:
Other images and data are here:
Here's hoping that this comet survives to provide a nice display
post-perihelion. Sadly, us northern observers won't get much of a chance
to see it so we will be relying on reports from the southern hemisphere.
Nick James. BAA Comet Section.
On 28/12/2024 07:42, Michael Mattiazzo via wrote:
> Howdy Folks,
>
>?
>
> C/2024 G3 ATLAS has been kept under extensive observation by several observers, despite its poor location.
>
> Attached a light curve showing a steady brightening toward perihelion that could see it reach magnitude -3, if it survives.
>
> I’ve also attached? images from Dec 25 and 26 showing a curious spine feature (often seen in outbursting comets) but this comet is not in outburst.
>
> Hopefully there is sufficient nuclear material to keep going. It is a very dusty comet as seen with the parabolic hood.
>
> This situation reminds me of C/2002 V1 NEAT in March 2023
>
>?
>
> Cheers,
>
> Michael
>
>
>
>
>
>
>
|
Re: Unusual brightening of comet C/2023 Q1
Denis, Jakub, Bob, friends, As told previously, I am tired after three consecutive nights ( Dec. 26, 27, 28 ) observing comets from the snowy Cantabrian Mountains. So this will be a short reply ... Denis : Quoting your words : " ... you previously mentioned you had spoken you last words on this subject, so it is suprising to hear back from you ..." My reply was motivated by my obvious disagreement with your previous comment [ "... in the overall description of the condition of this comet I would say that that feature ( the faint outer coma ) ?is a minor component of the comet ... ] and an implicit general undervaluation of the estimates of the visual observers with respect to CCD photometry.
Quoting my words : "CCD and visual data are ?complementary, not exclusive". Jakub : Being really very tired, and needing a long recovery sleep, I don't want to have a long and detailed debate like in the old days, regarding the same issues comparing visual estimates and CCD measures.
But quoting your words : " Therefore, the reported visual observation may be in error—either in the estimated magnitude or the coma diameter. The observer should re-examine their observation to identify where the discrepancy arose ..." I must say that both data ( m1, coma diameter ), and the change in position of the comet, have been verified on two consecutive nights ( Dec. 27 + 28 ), Also from your words : " No one is flawless—myself included." I obviously agree ... " ... It has been demonstrated many times that observers can report objects or details they did not actually see." My visual observation of C/2023 Q1 was not a highly difficult one. I made a clear detection of the very diffuse outer coma. Quoting Bob's words : " It would be nice if we had some additional visual observers so there would be a pool of estimates to draw upon. " These are the words I was hoping to hear, as my initial contribution to this thread was to provide the input of visual observers. And now, really, just before going to sleep, I can seriously say that this will be my final post on this C/2023 Q1 thread. Best regards, J. J. Gonzalez Suarez P.S.: I wish clear skies and good luck to those visual observers looking for the very diffuse C/2023 Q1. -------------------------------------------------------------------------------------------------------------------------------------------------------
On Sun, Dec 29, 2024 at 9:26?PM Denis Buczynski via <buczynski8166= [email protected]> wrote:
Bob,
It will be intersting to see your report when you are able to observe
then comet. JJ was observing from a high altitude mountain site and it
exceptional that he has been able to observe this faint (mag 15 from my
own digital observations)comet. I am not suprised there are no other
visual reports of this comet, it is faint for visual observers, but an
relatively easy target for imagers. The feat of visually observing a
faint outer coma would seem to be difficult in a comet this faint.
However according to JJ he did indeed acheive this.
Best wishes
Denis
? ? ? ? ------ Original Message ------
? ? ? ? From: nightsky55=[email protected]
? ? ? ? To: [email protected]
? ? ? ? Sent: Sunday, December 29th 2024, 20:09
? ? ? ? Subject: Re: [comets-ml] Unusual brightening of comet C/2023 Q1
? Jakub and all,
? This discussion has inspired me to observe C/2023 Q1 in my 38-cm
reflector at the next opportunity. I also have a very
? dark sky especially in the north direction — when the aurora isn't
active! It would be nice if we had some additional visual observers so
there would be
? a pool of estimates to draw upon. J.J. Gonzalez Suarez's observation
is the only visual sighting of the comet I'm aware of.
? Bob
? On Sun, Dec 29, 2024 at 1:17?PM Jakub ?ern? via
<kaos=[email protected]> wrote:
? ? ? ? ? ? ? ? ? ? ? Hello all,
? ? ? ?If I have read the posts correctly, we have two observations:
? ? ? ?CCD magnitude of 14.1 mag with a 5' aperture.? ? ? ?Visual
magnitude of 11.6 mag with a 6' aperture.? ? ? ? ? How can we explain
such a large difference? The CCD method? ? ? ?measures flux in a chosen
aperture, and we know that a comet’s? ? ? ?surface brightness decreases
with distance from the central? ? ? ?condensation. However, even if the
surface brightness is? ? ? ?decreasing, the increase in the area of the
coma can still? ? ? ?significantly change the total measured magnitude.
? ? ? ?Regarding the well-known “CCD vs. visual” issue, it often arose
in the past from insufficient exposure times, which led observers to
measure only the central condensation in a smaller aperture, whereas
visual observers saw more of the coma. Even among visual observers
alone, an “aperture effect” has been described—smaller telescopes can
show a larger apparent coma and thus yield brighter magnitude estimates.
Hence, the 2–3 mag discrepancy was typically caused by different coma
sizes captured in visual vs. CCD observations. However, this problem has
largely faded in recent years as CCD observers have become more
experienced. With proper techniques, CCD observations now usually match
visual data closely, differing by only a few tenths of a magnitude due
to variations in spectral sensitivities (especially for unfiltered or
narrowband photometry vs. visual V or g' bands).
? ? ? ?It is unlikely that a difference of 2.5 mag could arise from
nearly the same apertures (5' vs. 6'), because an increase of just 1' in
aperture should not produce such a large magnitude gap under normal
circumstances.
? ? ? ?Although it is possible to measure an object as 2.5 mag brighter
by including a much larger coma with very low surface brightness (for
example, if the visual observation indicated a coma diameter of
15'–20'), this is not the situation described here. Therefore, the
reported visual observation may be in error—either in the estimated
magnitude or the coma diameter. The observer should re-examine their
observation to identify where the discrepancy arose.
? ? ? ?No one is flawless—myself included. It has been demonstrated many
times that observers can report objects or details they did not actually
see. There have even been cases where a comet was reported at the wrong
position. We must learn from such instances in order to provide
scientifically valuable data.
? ? ? ?Best regards,? ? ? ?Jakub ?ern?
|
Re: Unusual brightening of comet C/2023 Q1
Denis, Hoping for clear skies soon. I'll report back. Thanks, Bob On Sun, Dec 29, 2024 at 2:26?PM Denis Buczynski via <buczynski8166= [email protected]> wrote:
Bob,
It will be intersting to see your report when you are able to observe
then comet. JJ was observing from a high altitude mountain site and it
exceptional that he has been able to observe this faint (mag 15 from my
own digital observations)comet. I am not suprised there are no other
visual reports of this comet, it is faint for visual observers, but an
relatively easy target for imagers. The feat of visually observing a
faint outer coma would seem to be difficult in a comet this faint.
However according to JJ he did indeed acheive this.
Best wishes
Denis
? ? ? ? ------ Original Message ------
? ? ? ? From: nightsky55=[email protected]
? ? ? ? To: [email protected]
? ? ? ? Sent: Sunday, December 29th 2024, 20:09
? ? ? ? Subject: Re: [comets-ml] Unusual brightening of comet C/2023 Q1
? Jakub and all,
? This discussion has inspired me to observe C/2023 Q1 in my 38-cm
reflector at the next opportunity. I also have a very
? dark sky especially in the north direction — when the aurora isn't
active! It would be nice if we had some additional visual observers so
there would be
? a pool of estimates to draw upon. J.J. Gonzalez Suarez's observation
is the only visual sighting of the comet I'm aware of.
? Bob
? On Sun, Dec 29, 2024 at 1:17?PM Jakub ?ern? via
<kaos=[email protected]> wrote:
? ? ? ? ? ? ? ? ? ? ? Hello all,
? ? ? ?If I have read the posts correctly, we have two observations:
? ? ? ?CCD magnitude of 14.1 mag with a 5' aperture.? ? ? ?Visual
magnitude of 11.6 mag with a 6' aperture.? ? ? ? ? How can we explain
such a large difference? The CCD method? ? ? ?measures flux in a chosen
aperture, and we know that a comet’s? ? ? ?surface brightness decreases
with distance from the central? ? ? ?condensation. However, even if the
surface brightness is? ? ? ?decreasing, the increase in the area of the
coma can still? ? ? ?significantly change the total measured magnitude.
? ? ? ?Regarding the well-known “CCD vs. visual” issue, it often arose
in the past from insufficient exposure times, which led observers to
measure only the central condensation in a smaller aperture, whereas
visual observers saw more of the coma. Even among visual observers
alone, an “aperture effect” has been described—smaller telescopes can
show a larger apparent coma and thus yield brighter magnitude estimates.
Hence, the 2–3 mag discrepancy was typically caused by different coma
sizes captured in visual vs. CCD observations. However, this problem has
largely faded in recent years as CCD observers have become more
experienced. With proper techniques, CCD observations now usually match
visual data closely, differing by only a few tenths of a magnitude due
to variations in spectral sensitivities (especially for unfiltered or
narrowband photometry vs. visual V or g' bands).
? ? ? ?It is unlikely that a difference of 2.5 mag could arise from
nearly the same apertures (5' vs. 6'), because an increase of just 1' in
aperture should not produce such a large magnitude gap under normal
circumstances.
? ? ? ?Although it is possible to measure an object as 2.5 mag brighter
by including a much larger coma with very low surface brightness (for
example, if the visual observation indicated a coma diameter of
15'–20'), this is not the situation described here. Therefore, the
reported visual observation may be in error—either in the estimated
magnitude or the coma diameter. The observer should re-examine their
observation to identify where the discrepancy arose.
? ? ? ?No one is flawless—myself included. It has been demonstrated many
times that observers can report objects or details they did not actually
see. There have even been cases where a comet was reported at the wrong
position. We must learn from such instances in order to provide
scientifically valuable data.
? ? ? ?Best regards,? ? ? ?Jakub ?ern?
|
Re: Unusual brightening of comet C/2023 Q1
Bob,
It will be intersting to see your report when you are able to observe then comet. JJ was observing from a high altitude mountain site and it exceptional that he has been able to observe this faint (mag 15 from my own digital observations)comet. I am not suprised there are no other visual reports of this comet, it is faint for visual observers, but an relatively easy target for imagers. The feat of visually observing a faint outer coma would seem to be difficult in a comet this faint. However according to JJ he did indeed acheive this.
Best wishes
Denis
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------ Original Message ------ From: nightsky55@... To: [email protected] Sent: Sunday, December 29th 2024, 20:09 Subject: Re: [comets-ml] Unusual brightening of comet C/2023 Q1 Jakub and all, This discussion has inspired me to observe C/2023 Q1 in my 38-cm reflector at the next opportunity. I also have a very dark sky especially in the north direction — when the aurora isn't active! It would be nice if we had some additional visual observers so there would be a pool of estimates to draw upon. J.J. Gonzalez Suarez's observation is the only visual sighting of the comet I'm aware of. Bob On Sun, Dec 29, 2024 at 1:17?PM Jakub ?ern? via groups.io <kaos@...> wrote: Hello all, If I have read the posts correctly, we have two observations: CCD magnitude of 14.1 mag with a 5' aperture. Visual magnitude of 11.6 mag with a 6' aperture. How can we explain such a large difference? The CCD method measures flux in a chosen aperture, and we know that a comet’s surface brightness decreases with distance from the central condensation. However, even if the surface brightness is decreasing, the increase in the area of the coma can still significantly change the total measured magnitude. Regarding the well-known “CCD vs. visual” issue, it often arose in the past from insufficient exposure times, which led observers to measure only the central condensation in a smaller aperture, whereas visual observers saw more of the coma. Even among visual observers alone, an “aperture effect” has been described—smaller telescopes can show a larger apparent coma and thus yield brighter magnitude estimates. Hence, the 2–3 mag discrepancy was typically caused by different coma sizes captured in visual vs. CCD observations. However, this problem has largely faded in recent years as CCD observers have become more experienced. With proper techniques, CCD observations now usually match visual data closely, differing by only a few tenths of a magnitude due to variations in spectral sensitivities (especially for unfiltered or narrowband photometry vs. visual V or g' bands). It is unlikely that a difference of 2.5 mag could arise from nearly the same apertures (5' vs. 6'), because an increase of just 1' in aperture should not produce such a large magnitude gap under normal circumstances. Although it is possible to measure an object as 2.5 mag brighter by including a much larger coma with very low surface brightness (for example, if the visual observation indicated a coma diameter of 15'–20'), this is not the situation described here. Therefore, the reported visual observation may be in error—either in the estimated magnitude or the coma diameter. The observer should re-examine their observation to identify where the discrepancy arose. No one is flawless—myself included. It has been demonstrated many times that observers can report objects or details they did not actually see. There have even been cases where a comet was reported at the wrong position. We must learn from such instances in order to provide scientifically valuable data. Best regards, Jakub ?ern?
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Re: Unknown object in M15 image on Nov 27, 2024
Peter, That was absolutely brilliant. What a great sleuthing method! Bob On Sun, Dec 29, 2024 at 9:39?AM Peter Birtwhistle via <peter= [email protected]> wrote:
John,
I think the stacking may have registered a frame incorrectly
causing a faint image of the centre of M15 to appear offset to the
west.
I've blinked the B-27 image with the Dec 20 image and there are
(at least) three bright stars extra on the B-27 image along with
the unknown object but all four objects appear displaced from
bright stars (and M15) as the attached image shows.
Peter
J95
On 29/12/2024 15:11, John Hart McCue via wrote:
[Edited Message Follows]
Hello
all,
I'm
a new member, MPC recommended your group. I live near the
North York Moors National Dark Skies Park, northeast UK, and
recently bought a Seestar S50 to help them with outreach. To
familiarise myself with it, I imaged M15 on Nov. 27, 2024. I
didn’t scrutinise the image in detail until 8 Dec., and
noticed the extended object just to the right of the cluster.
The image prefixed A is the stacked 19 min. R filter exposure.
The Seestar’s camera is a Sony IMX462, with a CMOS sensor
which has a resolution of 1920 x 1080 pixels (2 MP). The image
prefixed B is the same stacked image but de-noised with the
Seestar's AI function on Dec. 8. My next clear nights were on
19 and 20 Dec., and I imaged M15 again with approximately the
same length of exposure. The sky transparency on Nov 27 was
slightly better than that on Dec 19 and 20, but there was no
sign of the unknown object.
Using
and the Skychart
software (CdC),I estimate the object's J2000 position as 21h
29m 27.9s, +12 deg. 11' 44”, with approximate error 5”, and a
rough magnitude of 16 error 1, though I don’t have a lot of
experience estimating cometary magnitudes.
I
web-searched for M15 images, and also searched the British
Astronomical Association's Deep Sky Gallery (of which I am a
member) with no sign of the object so no obvious
identification. I also searched the deep sky databases on the
software Cartes du Ciel (Skychart), again to no avail. I was
observatory code 937 in the northeast of England, but have now
moved house about 15 miles to the east.
MPC
have just told me that they could not locate
any known objects at my given position and date and
suggested, as I mentioned, that I post a message to your
group.
MPC said maybe someone can track down archive images of the
region near that date.?
Best
wishes for a happy new year,
John
|
Re: Unusual brightening of comet C/2023 Q1
Jakub and all,
This discussion has inspired me to observe C/2023 Q1 in my 38-cm reflector at the next opportunity. I also have a very dark sky especially in the north direction — when the aurora isn't active! It would be nice if we had some additional visual observers so there would be a pool of estimates to draw upon. J.J. Gonzalez Suarez's observation is the only visual sighting of the comet I'm aware of.
Bob
Hello all,
If I have read the posts correctly, we have two observations:
- CCD magnitude of 14.1 mag with a 5' aperture.
- Visual magnitude of 11.6 mag with a 6' aperture.
How can we explain such a large difference? The CCD method
measures flux in a chosen aperture, and we know that a comet’s
surface brightness decreases with distance from the central
condensation. However, even if the surface brightness is
decreasing, the increase in the area of the coma can still
significantly change the total measured magnitude.
Regarding the well-known “CCD vs. visual” issue, it often arose
in the past from insufficient exposure times, which led observers
to measure only the central condensation in a smaller aperture,
whereas visual observers saw more of the coma. Even among visual
observers alone, an “aperture effect” has been described—smaller
telescopes can show a larger apparent coma and thus yield brighter
magnitude estimates. Hence, the 2–3 mag discrepancy was typically
caused by different coma sizes captured in visual vs. CCD
observations. However, this problem has largely faded in recent
years as CCD observers have become more experienced. With proper
techniques, CCD observations now usually match visual data
closely, differing by only a few tenths of a magnitude due to
variations in spectral sensitivities (especially for unfiltered or
narrowband photometry vs. visual V or g' bands).
It is unlikely that a difference of 2.5 mag could arise from
nearly the same apertures (5' vs. 6'), because an increase of just
1' in aperture should not produce such a large magnitude gap under
normal circumstances.
Although it is possible to measure an object as 2.5 mag brighter
by including a much larger coma with very low surface brightness
(for example, if the visual observation indicated a coma diameter
of 15'–20'), this is not the situation described here. Therefore,
the reported visual observation may be in error—either in the
estimated magnitude or the coma diameter. The observer should
re-examine their observation to identify where the discrepancy
arose.
No one is flawless—myself included. It has been demonstrated many
times that observers can report objects or details they did not
actually see. There have even been cases where a comet was
reported at the wrong position. We must learn from such instances
in order to provide scientifically valuable data.
Best regards,
Jakub ?ern?
|
Re: Unknown object in M15 image on Nov 27, 2024
Hi Bill,
This occasionally happens with Astrometrica, often occurring when an image is included in a stack by mistake with e.g. a bright artificial satellite crossing the field, throwing the software off.
Astrometrica doesn't directly warn when these happen, but normally they are very obvious to see in the final stacked image and the effect can also be seen in the Astrometrica log file which gives the X and Y pixel amounts that each image has been offset by.
I think in all the cases I've hit these are simple shifts (no rotation), same as in the M15 stack.
Peter
J95
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Show quoted text
On 29/12/2024 19:28, Bill J. Gray wrote: On 12/29/24 10:39, Peter Birtwhistle via groups.io wrote:> I think the stacking may have registered a frame incorrectly causing a
faint image of the centre of M15 to appear offset to the west. ?? Interesting.? I wonder how often such things happen?? Often enough that stacking software should attempt to detect them and warn you about it?
-- Bill
|
Re: Unknown object in M15 image on Nov 27, 2024
On 12/29/24 10:39, Peter Birtwhistle via groups.io wrote:> I think the stacking may have registered a frame incorrectly causing a faint image of the centre of M15 to appear offset to the west. Interesting. I wonder how often such things happen? Often enough that stacking software should attempt to detect them and warn you about it? -- Bill
|
Re: Unusual brightening of comet C/2023 Q1
Hello all,
If I have read the posts correctly, we have two observations:
- CCD magnitude of 14.1 mag with a 5' aperture.
- Visual magnitude of 11.6 mag with a 6' aperture.
How can we explain such a large difference? The CCD method
measures flux in a chosen aperture, and we know that a comet’s
surface brightness decreases with distance from the central
condensation. However, even if the surface brightness is
decreasing, the increase in the area of the coma can still
significantly change the total measured magnitude.
Regarding the well-known “CCD vs. visual” issue, it often arose
in the past from insufficient exposure times, which led observers
to measure only the central condensation in a smaller aperture,
whereas visual observers saw more of the coma. Even among visual
observers alone, an “aperture effect” has been described—smaller
telescopes can show a larger apparent coma and thus yield brighter
magnitude estimates. Hence, the 2–3 mag discrepancy was typically
caused by different coma sizes captured in visual vs. CCD
observations. However, this problem has largely faded in recent
years as CCD observers have become more experienced. With proper
techniques, CCD observations now usually match visual data
closely, differing by only a few tenths of a magnitude due to
variations in spectral sensitivities (especially for unfiltered or
narrowband photometry vs. visual V or g' bands).
It is unlikely that a difference of 2.5 mag could arise from
nearly the same apertures (5' vs. 6'), because an increase of just
1' in aperture should not produce such a large magnitude gap under
normal circumstances.
Although it is possible to measure an object as 2.5 mag brighter
by including a much larger coma with very low surface brightness
(for example, if the visual observation indicated a coma diameter
of 15'–20'), this is not the situation described here. Therefore,
the reported visual observation may be in error—either in the
estimated magnitude or the coma diameter. The observer should
re-examine their observation to identify where the discrepancy
arose.
No one is flawless—myself included. It has been demonstrated many
times that observers can report objects or details they did not
actually see. There have even been cases where a comet was
reported at the wrong position. We must learn from such instances
in order to provide scientifically valuable data.
Best regards,
Jakub ?ern?
|
Re: Unusual brightening of comet C/2023 Q1
Hi again JJ.
Thanks for your reply, always courteous and friendy. Some of what you write I agree with, some aspects are more contentious. However you previously mentioned you had spoken you last words on this subject, so it is suprising to hear back from you.
There are obvious differences to our observing methods which apparently result in differing reported values for comet magnitudes and coma sizes. It is down the the analysts to decide which observations to utilise and which to discard as outliers.That is not the purpose of those, like ourselves, who only wish to make the observations, in good faith,which are made using well defined observing methods.
One question I wouldl ike to know the answer to regarding your observing methodology is how you measure/determine the size of a very faint coma? Do you estimate its dimensions as a percentage of the visible field or do you use transit timings of the coma passing across the field of a stationary/undriven telescope?Also how do you exclude the tail (which is intermingled with the coma) from your estimates. I stress the word estimate. You will appreciate that what digital observers report are measurements.
In the field of stellar observations the initial magnitudes were detemined visually (BonnerD etc) but that methodology was ditched once an objective method of observing was available, ie photography, which in general was an objective independent and repeatable method. Our field of study, ie comets may be a vastly different subject, but some similarities are present
Best wishes
Denis Buczynski
ps you will appreciate that total comet magnitude measurment techniques have improved in software since the time that Giovanni made his comments some years ago. I have no doubt that Giovanni (as do his colleagues today) would have utilised comet measurement software to extract data from his digital images.
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------ Original Message ------ From: jjgsgp@... To: [email protected] Sent: Sunday, December 29th 2024, 18:41 Subject: Re: [comets-ml] Unusual brightening of comet C/2023 Q1 Denis, You deserve a good reply ...- Quoting your words : " My imaging may not have not recorded a very faint outer coma , but in the overall description of the condition of this comet I would say that that feature is a minor component of the comet and the major features which I have measured are the substantial ones."I disagree : the outer coma ?is not a minor component : From the ICQ Guide to observing comets ( Daniel Green, 1997 ) : " ... The ICQ adopted in 1986 the following definition fot total visual magnitude m1 of a comet : the integrated brightness of the comet's entire coma ( but not the tail ) that is visible above the sky background, determined with the smallest possible instrument needed to easily detect the coma ..." - Regarding the old "Visual vs. CCD" question.I've expressed my opinion in several previous threads. CCD and visual data are ?complementary, not exclusive. We ?( visual observers ) continue a very long observing tradition, adding our data to the historical records. It would be useful to quote here a highly experienced CCD observer and very good friend, Giovanni Sostero ( unfortunately deceased in 2012 ) :" IMHO most of the times the big troubles with some total cometary magnitude measurements, are not those provided by visual observers ( that are following a long and well documented methodology ) but the CCDs m1 photometry results ( for a number of reasons already discussed here several times ). This makes me more and more convinced that visual observers are still doing a precious work with their m1 estimates, even in these days of widespread hi-tech inviting "options". Then I hope that people like you, J.J., Alan Hale, etc. will not give up yours efforts...". Many thanks again, Giovanni, for your valued friendship and words ... Comparison between visual and CCD photometry depends appreciably on the each individual comet spectra ( species present in the coma, production rates, gas to dust ratio, ?... ) and the response of the detector ( human eye, CCD ), among other factors. In the present "CCD times", some visual observers ( and websites posting observations ) are biased by previously seen CCD images. But as said, we must report a comet's ( or comet-related object, like remnants ) observation data as accurately as we can, from the eyepiece to the paper, based on the correct methodology and personal experience. As told somewhere, CCD images aren't ALWAYS an evidence against a visual observation, as the C/2010 X1 remnant demonstrate. - From your words :" ... I admire your abilty to get into the clear dark mountain air to observe comets, and you must derive satisfaction from that ..."My primary motivation is the scientific utility of visual estimates.Quoting Dan Green, "observations of comets by amateurs ( unpaid observers ) are essential to the progress of cometary astronomy ..." - Another quote from Fred Whipple : "observing comets has broad effects in science, besides giving the observer personal pleasure". I will tell it again, is simple : I try to make the visual observations under the best available conditions. I work hard seeking for the higher and best observing dark sites, specially for comets near perihelion, and trying to observe as much coma diameter as possible, especially for low DC comets, and low altitude over the horizon. As a physicist I must report the estimates exactly as they are. - Finally, also from a previous ( old ) thread : It is appropriate to express a "cometary" sorrow, sometimes exposed by myself and frequently by other older fellows :As it seems, the times of the great visual comet observers are coming ( asymptotically ) to an end. We must remember here George Alcock, Bill Bradfield, and other inspiring names.What are the main causes ? Undoubtedly, light pollution has a broad impact on astronomical observations. Is progressively more difficult to observe from a good dark site. But there is another significant concurrent cause : generational relay is decreasing, and the younger people are more favorable to the CCD approach. At some time in the future, those photons coming from faint distant comets will not be directly observed by human eyes. Only the brightest ones will continue marvelling us over the night sky horizon.Best regards and clear skies,J. J. Gonzalez Suarez ------------------------------------------------------------------------ On Sun, Dec 29, 2024 at 1:24?PM Denis Buczynski via groups.io <buczynski8166@...> wrote: Hi JJ, I used the word debate in the context that the apparent magnitude of this comet is in debate, not your method of observing? or derived results. I do not want to have an argument about this.I only point out that the results I have obtained can be repeated and checked again , the images are in existance. Any one can measure them and see if they get the same results as myself. My imaging may not have not recorded a very faint outer coma , but in the overall description of the condition of this comet I would say that that feature is a minor component of the comet and the major features which I have measured are the substantial ones. The astrometry I and others have obtained are meaningful and will stand the test of time. I admire your abilty to get into the clear dark mountain air to observe comets, and you must derive satisfaction from that.? We are both comet observers, just operationally different. Best wishes Denis Buczynski ? ? ? ? ------ Original Message ------ ? ? ? ? From: jjgsgp@... ? ? ? ? To: [email protected] ? ? ? ? Sent: Sunday, December 29th 2024, 01:44 ? ? ? ? Subject: Re: [comets-ml] Unusual brightening of comet C/2023 Q1 ? Thomas, Denis, Peter, Jakub, all,Some recent further visual data :C/2023 Q1 (PANSTARRS):2024 Dec. 28.82 UT: m1=11.7 (AQ), Dia.=6', DC=1/, 20 cm SCT (77x).[ Faint, large and very diffuse outer coma, slightly enhanced through Swan Band filter. Nearby field stars checked in DSS. At 133x : m=13.3 (AQ) for the 1' inner coma diameter. Limiting star magnitude near comet : 14.5 (AQ). Mountain location, very clear sky.].( Collada de Aralla, 1500 m, Leon, Spain )And other comments ?:Denis, in your posts ?in this thread you mention the word "debate". For my part, by contributing my data I do not want to discuss the photometric measurements obtained with CCD/CMOS, I only add complementary information from another perspective ...On the other hand, the mentioned visual estimates of C/2023 Q1 and 29P cannot be compared, even if they are now of similar magnitude m1 and apparent diameter : the comae structure and composition are different, and Q1 is more diffuse.Thomas, I fully agree with you : "The aperture diameter MUST be taken into account when comparing data. The second important parameter is the spectral range covered."But regarding your report ( 2024-12-23.46 UT, m1=14.1, coma diam. 5'), I obviously disagree when you say "I would be very much surprised if it would be possible to detect the same amount of coma size visually".Best regards,J. J. Gonzalez Suarez--------------------------------------------------------------------------------- ? On Sun, Dec 29, 2024 at 12:07?AM Observatory Gr?mme via groups.io <observatorygromme@...> wrote: ? ? ? ? ?Dear All, ? ? For the moment i measure magnitude 16 using SDSS r' filter. Uncalibrated images. PhotAp 6.1arcsec ? ? From: [email protected] < [email protected]> on behalf of David Moore(Ireland) via groups.io <davefriend0@...> Sent: Saturday, December 28, 2024 2:19 PM To: [email protected] < [email protected]> Subject: Re: [comets-ml] Unusual brightening of comet C/2023 Q1 ? ? ?Skyglow? ? ?If coma diameter is 4' that's 45,000 sq " ? ?I think I saw a figure of 21mag per sq arcsec? ? ?So airglow alone would 'add' 11.6mag i.e. a patch of dark sky 4' in diameter is mag9.4? ? ?Is my maths wrong!? ? ? ?On Saturday 28 December 2024 at 12:05:34 GMT, Thomas Lehmann via groups.io <t.lehmann@...> wrote: ? ? Hi Denis,? here is a heavily processed image. Pretty ugly though, but it might serve for illustration purposes.? Something I'd add to my "total" coma mesurement within 5': the brighness measurement (statistical) uncertainty is about 0.15mag.? Best wishes Thomas? ?> Am Sat, 28 Dec 2024 11:43:28 +0000 (GMT) > schrieb "Denis Buczynski via groups.io" <buczynski8166@...>: > > Hi Thomas, > I appreciate all you say in this regard. > I would be more convinced that there was an extensive coma present if I? > could see an image showing this coma. Whether it be from fast f/2? > telescopes in excellent dark skies or from anywhere else . It only? > requires someone posting a current image showing an extensive coma to? > put this "debate " to rest.We have yet to see one. > Best wishes > Denis Buczynski >? >? >? ? ? ? ------ Original Message ------ >? ? ? ? From: t.lehmann@... >? ? ? ? To: jjgsgp@... Cc: [email protected] >? ? ? ? Sent: Saturday, December 28th 2024, 11:17 >? ? ? ? Subject: Re: [comets-ml] Unusual brightening of comet C/2023 Q1 >? >? >? >? Dear all, >? >? thanks for the numerous observation reports, especially to Denis's and? > Peter's >? measurements over longer time span. >? >? I'd like to emphasize that any brightness measurement MUST be read in >? conjunction to the measurement aperture used. The aperture diameter? > MUST be >? taken into account when comparing data. The second important parameter? > is >? the spectral range covered. The brightening from gaseous outbursts can? > be ? more prominent in the green filtered images than in unfiltered (or? > red) images. >? >? About visual estimates. >? My report of 2024-12-23.46 UT, m1=14.1, coma diam. 5' >? is derived from images using a fast f/2.2 scope under excellent skies? > having >? a limited stellar magnitude of 21mag and using heavy smoothing and? > contrast >? enhancement. I would be very much surprised if it would be possible to? > detect >? the same amount of coma size visually. It is even harder for me to? > accept that ? I have missed 90% of the comets coma flux in my measurement - which would be >? the case if the magnitude were near ~11.6mag - though I cannot rule? > out some >? additional outburst has happened recently. > ? Anyway, I'd like to encourage anyone to continue monitoring the comet. >? For those doing imaging, it would be nice if you could measure the? > coma >? additionally using a true aperture diameter of d=15000km and 30000km? > at the >? comet (and report filter information) so we would be able to construct? > a >? combined light curve of the inner coma brightness. >? >? Thanks >? Thomas >? >? >? > Am Sat, 28 Dec 2024 07:54:29 +0100 >? > schrieb "jjgonzalez jjgonzalez via groups.io"?? > <jjgsgp@...>: >? > >? > Thomas, Denis, Alan, all, >? > ? > Obviously, I am also interested in the confirmation of the large and?? > very >? > diffuse gas coma by visual observers from dark skies. ? > >? > Best regards, >? > >? > J. J. Gonzalez Suarez >? > >? > P.S.: ? > >? > As complementary information, this is the report of my recent? observation >? > of the large dust coma of 29P : >? > >? > 29P/Schwassmann-Wachmann: >? > 2024 Dec. 27.00 UT: m1=11.1, Dia.=4', DC=2/, 20 cm SCT (77x). >? > ( Cubiellos - Sierra del Aramo, 1510 m, Asturias, Spain ) >? > >? >?? > ----------------------------------------------------------------------------------------------------------- ? > >? > >? > On Sat, Dec 28, 2024 at 5:39?AM Alan Hale via groups.io [email protected]> wrote: >? >?? >? > > Dear Denis, all, >? > > >? > > >? > > >? > > I’m attaching an image I took of C/2023 Q1 via LCO-Tenerife on?? > December >? > > 26.97 UT (0.35-m Cassegrain, single 180-second image, unprocessed, >? > > uncropped (dimensions 30x30 arcmin)). I’ve had some trouble?? > getting >? > > measurements from the image (possible software issues), but would >? > > “guesstimate” the magnitude to be somewhere around 15-15.5. I had?? > not >? > > imaged the comet previously so I can’t comment about any recent?? > brightening. >? > > >? > > >? > > >? > > For comparison, I’m also attaching an image I took of 29P on?? > December >? > > 25.60 UT from LCO-Haleakala (0.35-m Cassegrain, single 150-second?? > image, >? > > also unprocessed and uncropped, 30x30 arcmin). About eight hours?? > before I >? > > took this image I observed the comet visually at m1 = 11.7, 5.5’?? > coma, DC >? > > ~1 (41 cm reflector, 70x). >? > > >? > > ? > > >? > > >? > > >? > > Sincerely, >? > > >? > > Alan >? > > >? > > ? > > >? > > Hello all, >? > > >? > > I must admit I am a little baffled by these reports of a?? > substantial >? > > >? > > increase in brightness of C/2023 Q1. >? > > >? > > Firstly Thomas? Lehmann reported an increase in the brightness of?? > this >? > > >? > > comet in November to mag 14.1 My observations made for astrometry?? > for >? > > ? > > the months of November and December (10 nights data) show the?? > comet only >? > > >? > > increasing from mag 17 to mag 16. >? > > >? > > This is borne out by Peter Carson and Francois Kugel's comments of?? > their >? > > >? > > own observations and measurements. >? > > >? > > Now JJ Gonzalez is reporting an observation on the night of Dec 27?? > of >? ? > > this comet with a magnitude of 11.6. >? > > >? > > My last
observation was a day or so earlier on Dec 25 and my?? > Comphot >? > > ? > > measurement gives a magnitude of 15.73 with a coma diameter of 34?? > arc >? > > >? > > secs. >? > > >? > > I attach my image. >? > > ? > >? Can someone confirm the apparent +4 mag increase in brightness? or of >? > > >? > > mine, Peter Carson's and Francois Kugel's observation results? >? > > >? > > >? > > >? > > Comets eh! >? > > >? > ? Happy NY >? > > >? > > Denis Buczynski >? > > >? > > BAA Comet Section >? > > >? > > >? > > >? > > >? > > >? > > >? > > >? > >? ? ? ? ------ Original Message ------ >? > > >? > >? ? ? ? From: jjgsgp@... >? > > >? > >? ? ? ? To: [email protected] ? > > >? > >? ? ? ? Sent: Friday, December 27th 2024, 23:52 >? > > >? > ? ? ? ? Subject: Re: [comets-ml] Unusual brightening of comet?? > C/2023 Q1 >? > > >? > > >? > > >? > > >? > > >? > >? Thomas, all,After reading your email sent to the list yesterday,?? > I >? > > >? > > have arranged an observing session for tonight. This is the report >? > > >? :C/2023 Q1 (PANSTARRS):2024 Dec. 27.81 UT: m1=11.6, Dia.=6',?? >
DC=1/, 20 >? > > >? > > cm SCT (77x).[ From dark mountain skies the comet appears visually?? > much >? > > >? > > brighter than expected, showing a faint, large and very diffuse?? > outer >? > > >? > > coma. Nearby field stars checked in DSS. Limiting star magnitude?? > near >? > ? > > comet : 14.2 (AQ).].( Cubiellos - Sierra del Aramo, 1510 m,?? >
Asturias, >? > > >? > > Spain ). All the best from the Cantabrian Mountains,J. J. Gonzalez >? > > >? > > >? > >?? > Suarez-------------------------------------------------------------------------------------------------------------------------- ? > > >? > > >? > > >? > > >? > > >? > >? On Fri, Dec 27, 2024 at 5:28?PM Shanklin, Jonathan D. via?? > groups.io >? > > >? > > <jdsh@...> wrote: >? > > >? > >? ? ? ? ? My entry for the comet for The Astronomer magazine?? > covering >? > > >? > > observations to the end of November and giving the behaviour for >? > > ? > > November was: >? > > >? > >? ? 2023 Q1 (PANSTARRS) observations cover: -144 to -16 days, 2.6 –?? > 3.0 >? > > >? > > au >? > > >? > >? ? At 17.5, steady (Carson, Pappa) >? > > >? > > >? > > >? > >? ? Which does suggest that the brightness seen in December is >? > > >? > > unexpected. >? > > >? > > >? > > >? > >? ? I won’t start putting the TA column for the next issue together?? > until >? > > >? > > around January 4. >? > > >? > > >? > > >? > > >? > > >? > >? ? Regards, >? > > ? > > >? > > >? > >? ? Jonathan Shanklin >? > > >? > >? ? BAA Comet Section visual observations co-ordinator >? > > >? > >? ? >? > > >? > > >? > > >? > > >? > > >? ? > > >? > > >? > > >? > >? ? ? From: [email protected]
< [email protected]> On Behalf Of?? > Peter >? > > >? > > Carson via groups.io Sent: Friday, December 27, 2024 3:37 PM To: >? > > >? > > [email protected] Subject: [comets-ml] Unusual brightening of?? > comet >? > > >? > > C/2023 Q1 >? > > >? > > >? > > >? > > >? > > >? > > ? > > >? > >? ? ? ? You don't often get email from >? > > >? > > petercarson100@.... Learn why this is important >? > > ? > > >? > > >? > > >? > > >? > > >? > > >? > >? ? Hello Thomas, >? > > ? > > >? > > >? > >? ? Here are my observations from summer to now. Unfortunately, I?? > made >? > > >? > > no observations in October and early November, so although the?? > comet has >? > > >? > > brightened, it is not? clear if the brightening occurred over a?? > short or >? > > ? > > long period. >? > > >? > > >? > > >? > > >? > > >? > > >? > > >?
? ? All the best >? > > >? > > >? > > >? > >? ? Peter >? > > >? > > ? > > >? > > >? > > >? > > >? > > >? > >? ? Type Comet Obs? ? ? ? ? ? ? ? ? ? ? ? date Meth >? > > >? > > Mag Refcat Inst T App Inst F Inst P Coma User Location >? > > >? > > >? > > >? > >? ? CCD C/2023 Q1 22/12/2024 >? > > >? > > 21:11 Z 15.6 GG C 31.5 8 1260 0.80' CAR06 PGC ? > > >? > > Observatory Z10, Fregenal de la sierra, Spain >? > > >? >
? > > >? > >? ? CCD C/2023 Q1 10/12/2024 >? > > >? > > 03:18 Z 15.9 GG C 31.5 8 1200 0.80' CAR06 PGC >? > > >? > > Observatory Z10, Fregenal de la sierra, Spain >? > > >? > > >? > > >? > >? ? CCD C/2023 Q1 27/11/2024 >? > > >? > > 02:43 Z 16.1 GG C 31.5 8 1200 0.80' CAR06 PGC ? > > >? > > Observatory Z10, Fregenal de la sierra, Spain >? > > >? >
? > > >? > >? ? CCD C/2023 Q1 04/09/2024 >? > > >? > > 01:48 Z 17.5 GG C 31.5 8 1200 0.40' CAR06 PGC >? > > >? > > Observatory Z10, Fregenal de la sierra, Spain >? > > >? > > >? > > >? > >? ? CCD C/2023 Q1 16/08/2024 >? > > >? > > 03:21 Z 17.1 GG C 31.5 8 960 0.40' CAR06 PGC >? ? > > Observatory Z10, Fregenal de la sierra, Spain >? > > >? > >
? > > >? > >? ? CCD C/2023 Q1 05/08/2024 >? > > >? > > 02:33 Z 17.4 GG
C 31.5 8 960 0.40' CAR06 PGC >? > > >? > > Observatory Z10, Fregenal de la sierra, Spain >? > > >? > > >? > > >? > >? ? CCD C/2023 Q1 16/07/2024 ? > > >? > > 02:52 Z 17.5 GG C 31.5 8 1080 0.40' CAR06 PGC >? > > >? > Observatory Z10, Fregenal de la sierra, Spain >? > > >? > > >? > > >?
? ? CCD C/2023 Q1 10/07/2024 >? > > >? > > 02:39 Z 17.5 GG C 31.5 8 1200 0.40' CAR06 PGC >? > > >? > > Observatory Z10, Fregenal de la sierra, Spain >? > > >? > > >? > > >? > > >? > > >? > > >? > > >? > > >? ? > > >? > > >? > > >? > > >? > > >? > > >? > > >? > > >? > >? ?
From: [email protected] < [email protected]> on behalf of?? > Thomas ? > > >? > > Lehmann via groups.io <t.lehmann@...> Sent: 26 >? > > >? > > December 2024 22:19 To: [email protected] < [email protected]> >? > > >? > > Subject: [comets-ml] Unusual brightening of comet C/2023 Q1 >? > > >? > > >? > > >? > > >? > > >? > > ? > > >? > >? ? ? According to observations by S. Fritsche and myself the?? > comet >? > > >? > > C/2023 Q1 has started a sudden brightening in November.?? > Unfortunately >? > > >? > > our observations are very sparse due to the bad weather during the?? > last >? > > >? > > two months. Our data suggest a brightening by 1-2 mag between?? > October >? ? > > 26th and November 30th.? Latest measurement (green channel):
? > > >? > > 2024-12-23.46 UT, m1=14.1, coma diam. 5'? A more thorough? investigation >? > > >? > > by using small aperture measurements is on
the way.? Thanks to?? > all >? > > >? > > contributors for sharing results and ideas/thoughts to this list.?? > Merry >? > > >? > > Christmas and best wishes to all of you, Thomas >? > > >? > > >? > > >? ? > > >? > > >? > > >? > > >? > > >? > > >? > > >? > > >? > > >? >
? ? ? This email and any attachments are intended solely for the?? >
use of >? > > >? > > the named recipients. If you are not the intended recipient you?? > must not >? > > >? > > use, disclose, copy or distribute this email or any of its?? > attachments >? > > >? > > and should notify the sender immediately and delete? this email?? > from >? ? > > your system. UK Research and Innovation (UKRI) has taken
every >? > > >? > > reasonable precaution to minimise risk of this email or any?? > attachments >? > > >? > > containing viruses or malware but the recipient should carry out?? > its own >? > > >? > > virus and malware checks before? opening the attachments. UKRI?? > does not >? > > ? > > accept any liability for any losses or damages which the recipient?? > may >? > > >? > > sustain due to presence of any viruses. ? > > >? > > >? > > >? > > >? > > >? > > >? > > >? > > >? > > >? > > >?
? > > >? > > >? > > >? > > >? > > >? > > >? > > >? > > >? > > >? > ? > > >? > > >? > > >? > > >? > > >? > > >? > > >? > >?? >? > >? > >? ? > >? >?? >? >? >?? >? >? >? >? >? >? >? >? >? >
|
Re: Unusual brightening of comet C/2023 Q1
Denis, You deserve a good reply ... - Quoting your words :
" My imaging may not have not recorded a very faint outer coma , but in the overall description of the condition of this comet I would say that that feature is a minor component of the comet and the major features which I have measured are the substantial ones." I disagree : the outer coma ?is not a minor component : From the ICQ Guide to observing comets ( Daniel Green, 1997 ) :
" ... The ICQ adopted in 1986 the following definition fot total visual magnitude m1 of a comet : the integrated brightness of the comet's entire coma ( but not the tail ) that is visible above the sky background, determined with the smallest possible instrument needed to easily detect the coma ..."
- Regarding the old "Visual vs. CCD" question. I've expressed my opinion in several previous threads. CCD and visual data are ?complementary, not exclusive. We ?( visual observers ) continue a very long observing tradition, adding our data to the historical records.
It would be useful to quote here a highly experienced CCD observer and very good friend, Giovanni Sostero ( unfortunately deceased in 2012 ) : " IMHO most of the times the big troubles with some total cometary magnitude measurements, are not those provided by visual observers ( that are following a long and well documented methodology ) but the CCDs m1 photometry results ( for a number of reasons already discussed here several times ). This makes me more and more convinced that visual observers are still doing a precious work with their m1 estimates, even in these days of widespread hi-tech inviting "options". Then I hope that people like you, J.J., Alan Hale, etc. will not give up yours efforts...".
Many thanks again, Giovanni, for your valued friendship and words ...
Comparison between visual and CCD photometry depends appreciably on the each individual comet spectra ( species present in the coma, production rates, gas to dust ratio, ?... ) and the response of the detector ( human eye, CCD ), among other factors.
In the present "CCD times", some visual observers ( and websites posting observations ) are biased by previously seen CCD images. But as said, we must report a comet's ( or comet-related object, like remnants ) observation data as accurately as we can, from the eyepiece to the paper, based on the correct methodology and personal experience.
As told somewhere, CCD images aren't ALWAYS an evidence against a visual observation, as the C/2010 X1 remnant demonstrate.
- From your words : " ... I admire your abilty to get into the clear dark mountain air to observe comets, and you must derive satisfaction from that ..." My primary motivation is the scientific utility of visual estimates. Quoting Dan Green, "observations of comets by amateurs ( unpaid observers ) are essential to the progress of cometary astronomy ..."
- Another quote from Fred Whipple : "observing comets has broad effects in science, besides giving the observer personal pleasure". I will tell it again, is simple : I try to make the visual observations under the best available conditions. I work hard seeking for the higher and best observing dark sites, specially for comets near perihelion, and trying to observe as much coma diameter as possible, especially for low DC comets, and low altitude over the horizon. As a physicist I must report the estimates exactly as they are.
- Finally, also from a previous ( old ) thread :
It is appropriate to express a "cometary" sorrow, sometimes exposed by myself and frequently by other older fellows : As it seems, the times of the great visual comet observers are coming ( asymptotically ) to an end. We must remember here George Alcock, Bill Bradfield, and other inspiring names. What are the main causes ? Undoubtedly, light pollution has a broad impact on astronomical observations. Is progressively more difficult to observe from a good dark site. But there is another significant concurrent cause : generational relay is decreasing, and the younger people are more favorable to the CCD approach.
At some time in the future, those photons coming from faint distant comets will not be directly observed by human eyes. Only the brightest ones will continue marvelling us over the night sky horizon. Best regards and clear skies, J. J. Gonzalez Suarez ------------------------------------------------------------------------
On Sun, Dec 29, 2024 at 1:24?PM Denis Buczynski via <buczynski8166= [email protected]> wrote:
Hi JJ,
I used the word debate in the context that the apparent magnitude of
this comet is in debate, not your method of observing? or derived
results. I do not want to have an argument about this.I only point out
that the results I have obtained can be repeated and checked again , the
images are in existance. Any one can measure them and see if they get
the same results as myself. My imaging may not have not recorded a very
faint outer coma , but in the overall description of the condition of
this comet I would say that that feature is a minor component of the
comet and the major features which I have measured are the substantial
ones. The astrometry I and others have obtained are meaningful and will
stand the test of time. I admire your abilty to get into the clear dark
mountain air to observe comets, and you must derive satisfaction from
that.? We are both comet observers, just operationally different.
Best wishes
Denis Buczynski
? ? ? ? ------ Original Message ------
? ? ? ? From: jjgsgp=[email protected]
? ? ? ? To: [email protected]
? ? ? ? Sent: Sunday, December 29th 2024, 01:44
? ? ? ? Subject: Re: [comets-ml] Unusual brightening of comet C/2023 Q1
? Thomas, Denis, Peter, Jakub, all,Some recent further visual data
:C/2023 Q1 (PANSTARRS):2024 Dec. 28.82 UT: m1=11.7 (AQ), Dia.=6', DC=1/,
20 cm SCT (77x).[ Faint, large and very diffuse outer coma, slightly
enhanced through Swan Band filter. Nearby field stars checked in DSS. At
133x : m=13.3 (AQ) for the 1' inner coma diameter. Limiting star
magnitude near comet : 14.5 (AQ). Mountain location, very clear sky.].(
Collada de Aralla, 1500 m, Leon, Spain )And other comments ?:Denis, in
your posts ?in this thread you mention the word "debate". For my part,
by contributing my data I do not want to discuss the photometric
measurements obtained with CCD/CMOS, I only add complementary
information from another perspective ...On the other hand, the mentioned
visual estimates of C/2023 Q1 and 29P cannot be compared, even if they
are now of similar magnitude m1 and apparent diameter : the comae
structure and composition are different, and Q1 is more diffuse.Thomas,
I fully agree with you : "The aperture diameter MUST be taken into
account when comparing data. The second important parameter is the
spectral range covered."But regarding your report ( 2024-12-23.46 UT,
m1=14.1, coma diam. 5'), I obviously disagree when you say "I would be
very much surprised if it would be possible to detect the same amount of
coma size visually".Best regards,J. J. Gonzalez
Suarez---------------------------------------------------------------------------------
? On Sun, Dec 29, 2024 at 12:07?AM Observatory Gr?mme via
<observatorygromme=[email protected]> wrote:
? ? ? ? ?Dear All,
? ? For the moment i measure magnitude 16 using SDSS r' filter.
Uncalibrated images. PhotAp 6.1arcsec
? ? From: [email protected] <[email protected]> on behalf of David
Moore(Ireland) via <davefriend0=[email protected]> Sent:
Saturday, December 28, 2024 2:19 PM To: [email protected]
<[email protected]> Subject: Re: [comets-ml] Unusual brightening of
comet C/2023 Q1 ?
? ?Skyglow?
? ?If coma diameter is 4' that's 45,000 sq "
? ?I think I saw a figure of 21mag per sq arcsec?
? ?So airglow alone would 'add' 11.6mag i.e. a patch of dark sky 4' in
diameter is mag9.4?
? ?Is my maths wrong!?
? ? ?On Saturday 28 December 2024 at 12:05:34 GMT, Thomas Lehmann via
<t.lehmann=[email protected]> wrote:
? ? Hi Denis,? here is a heavily processed image. Pretty ugly though,
but it might serve for illustration purposes.? Something I'd add to my
"total" coma mesurement within 5': the brighness measurement
(statistical) uncertainty is about 0.15mag.? Best wishes Thomas? ?> Am
Sat, 28 Dec 2024 11:43:28 +0000 (GMT) > schrieb "Denis Buczynski via
" <buczynski8166=[email protected]>: > > Hi Thomas, > I
appreciate all you say in this regard. > I would be more convinced that
there was an extensive coma present if I? > could see an image showing
this coma. Whether it be from fast f/2? > telescopes in excellent dark
skies or from anywhere else . It only? > requires someone posting a
current image showing an extensive coma to? > put this "debate " to
rest.We have yet to see one. > Best wishes > Denis Buczynski >? >? >? ?
? ? ------ Original Message ------ >? ? ? ? From:
t.lehmann=[email protected] >? ? ? ? To: jjgsgp=[email protected]
> Cc: [email protected] >? ? ? ? Sent: Saturday, December 28th 2024,
11:17 >? ? ? ? Subject: Re: [comets-ml] Unusual brightening of comet
C/2023 Q1 >? >? >? >? Dear all, >? >? thanks for the numerous
observation reports, especially to Denis's and? > Peter's >?
measurements over longer time span. >? >? I'd like to emphasize that any
brightness measurement MUST be read in >? conjunction to the measurement
aperture used. The aperture diameter? > MUST be >? taken into account
when comparing data. The second important parameter? > is >? the
spectral range covered. The brightening from gaseous outbursts can? > be
>? more prominent in the green filtered images than in unfiltered (or? >
red) images. >? >? About visual estimates. >? My report of 2024-12-23.46
UT, m1=14.1, coma diam. 5' >? is derived from images using a fast f/2.2
scope under excellent skies? > having >? a limited stellar magnitude of
21mag and using heavy smoothing and? > contrast >? enhancement. I would
be very much surprised if it would be possible to? > detect >? the same
amount of coma size visually. It is even harder for me to? > accept that
>? I have missed 90% of the comets coma flux in my measurement - which
> would be >? the case if the magnitude were near ~11.6mag - though I
cannot rule? > out some >? additional outburst has happened recently. >
>? Anyway, I'd like to encourage anyone to continue monitoring the
comet. >? For those doing imaging, it would be nice if you could measure
the? > coma >? additionally using a true aperture diameter of d=15000km
and 30000km? > at the >? comet (and report filter information) so we
would be able to construct? > a >? combined light curve of the inner
coma brightness. >? >? Thanks >? Thomas >? >? >? > Am Sat, 28 Dec 2024
07:54:29 +0100 >? > schrieb "jjgonzalez jjgonzalez via "?? >
<jjgsgp=[email protected]>: >? > >? > Thomas, Denis, Alan, all, >? >
>? > Obviously, I am also interested in the confirmation of the large
and?? > very >? > diffuse gas coma by visual observers from dark skies.
>? > >? > Best regards, >? > >? > J. J. Gonzalez Suarez >? > >? > P.S.:
>? > >? > As complementary information, this is the report of my recent?
> observation >? > of the large dust coma of 29P : >? > >? >
29P/Schwassmann-Wachmann: >? > 2024 Dec. 27.00 UT: m1=11.1, Dia.=4',
DC=2/, 20 cm SCT (77x). >? > ( Cubiellos - Sierra del Aramo, 1510 m,
Asturias, Spain ) >? > >? >?? >
-----------------------------------------------------------------------------------------------------------
>? > >? > >? > On Sat, Dec 28, 2024 at 5:39?AM Alan Hale via
> [email protected]> wrote: >? >?? >? > > Dear Denis,
all, >? > > >? > > >? > > >? > > I’m attaching an image I took of C/2023
Q1 via LCO-Tenerife on?? > December >? > > 26.97 UT (0.35-m Cassegrain,
single 180-second image, unprocessed, >? > > uncropped (dimensions 30x30
arcmin)). I’ve had some trouble?? > getting >? > > measurements from the
image (possible software issues), but would >? > > “guesstimate” the
magnitude to be somewhere around 15-15.5. I had?? > not >? > > imaged
the comet previously so I can’t comment about any recent?? >
brightening. >? > > >? > > >? > > >? > > For comparison, I’m also
attaching an image I took of 29P on?? > December >? > > 25.60 UT from
LCO-Haleakala (0.35-m Cassegrain, single 150-second?? > image, >? > >
also unprocessed and uncropped, 30x30 arcmin). About eight hours?? >
before I >? > > took this image I observed the comet visually at m1 =
11.7, 5.5’?? > coma, DC >? > > ~1 (41 cm reflector, 70x). >? > > >? > >
>? > > >? > > >? > > >? > > Sincerely, >? > > >? > > Alan >? > > >? > >
>? > > >? > > Hello all, >? > > >? > > I must admit I am a little
baffled by these reports of a?? > substantial >? > > >? > > increase in
brightness of C/2023 Q1. >? > > >? > > Firstly Thomas? Lehmann reported
an increase in the brightness of?? > this >? > > >? > > comet in
November to mag 14.1 My observations made for astrometry?? > for >? > >
>? > > the months of November and December (10 nights data) show the?? >
comet only >? > > >? > > increasing from mag 17 to mag 16. >? > > >? > >
This is borne out by Peter Carson and Francois Kugel's comments of?? >
their >? > > >? > > own observations and measurements. >? > > >? > > Now
JJ Gonzalez is reporting an observation on the night of Dec 27?? > of >?
> > >? > > this comet with a magnitude of 11.6. >? > > >? > > My last
observation was a day or so earlier on Dec 25 and my?? > Comphot >? > >
>? > > measurement gives a magnitude of 15.73 with a coma diameter of
34?? > arc >? > > >? > > secs. >? > > >? > > I attach my image. >? > >
>? > >? Can someone confirm the apparent +4 mag increase in brightness?
> or of >? > > >? > > mine, Peter Carson's and Francois Kugel's
observation results? >? > > >? > > >? > > >? > > Comets eh! >? > > >? >
>? Happy NY >? > > >? > > Denis Buczynski >? > > >? > > BAA Comet
Section >? > > >? > > >? > > >? > > >? > > >? > > >? > > >? > >? ? ? ?
------ Original Message ------ >? > > >? > >? ? ? ? From:
jjgsgp=[email protected] >? > > >? > >? ? ? ? To: [email protected]
>? > > >? > >? ? ? ? Sent: Friday, December 27th 2024, 23:52 >? > > >? >
>? ? ? ? Subject: Re: [comets-ml] Unusual brightening of comet?? >
C/2023 Q1 >? > > >? > > >? > > >? > > >? > > >? > >? Thomas, all,After
reading your email sent to the list yesterday,?? > I >? > > >? > > have
arranged an observing session for tonight. This is the report >? > > >?
> > :C/2023 Q1 (PANSTARRS):2024 Dec. 27.81 UT: m1=11.6, Dia.=6',?? >
DC=1/, 20 >? > > >? > > cm SCT (77x).[ From dark mountain skies the
comet appears visually?? > much >? > > >? > > brighter than expected,
showing a faint, large and very diffuse?? > outer >? > > >? > > coma.
Nearby field stars checked in DSS. Limiting star magnitude?? > near >? >
> >? > > comet : 14.2 (AQ).].( Cubiellos - Sierra del Aramo, 1510 m,?? >
Asturias, >? > > >? > > Spain ). All the best from the Cantabrian
Mountains,J. J. Gonzalez >? > > >? > > >? > >?? >
Suarez--------------------------------------------------------------------------------------------------------------------------
>? > > >? > > >? > > >? > > >? > > >? > >? On Fri, Dec 27, 2024 at
5:28?PM Shanklin, Jonathan D. via?? > >? > > >? > >
<jdsh=[email protected]> wrote: >? > > >? > >? ? ? ? ? My entry for
the comet for The Astronomer magazine?? > covering >? > > >? > >
observations to the end of November and giving the behaviour for >? > >
>? > > November was: >? > > >? > >? ? 2023 Q1 (PANSTARRS) observations
cover: -144 to -16 days, 2.6 –?? > 3.0 >? > > >? > > au >? > > >? > >? ?
At 17.5, steady (Carson, Pappa) >? > > >? > > >? > > >? > >? ? Which
does suggest that the brightness seen in December is >? > > >? > >
unexpected. >? > > >? > > >? > > >? > >? ? I won’t start putting the TA
column for the next issue together?? > until >? > > >? > > around
January 4. >? > > >? > > >? > > >? > > >? > > >? > >? ? Regards, >? > >
>? > > >? > > >? > >? ? Jonathan Shanklin >? > > >? > >? ? BAA Comet
Section visual observations co-ordinator >? > > >? > >? ?
>? > > >? > > >? > > >? > > >? > > >?
> > >? > > >? > > >? > > >? > >? ? ? From: [email protected]
<[email protected]> On Behalf Of?? > Peter >? > > >? > > Carson via
Sent: Friday, December 27, 2024 3:37 PM To: >? > > >? > >
[email protected] Subject: [comets-ml] Unusual brightening of?? >
comet >? > > >? > > C/2023 Q1 >? > > >? > > >? > > >? > > >? > > >? > >
>? > > >? > >? ? ? ? You don't often get email from >? > > >? > >
petercarson100=[email protected]. Learn why this is important >? > >
>? > > >? > > >? > > >? > > >? > > >? > > >? > >? ? Hello Thomas, >? > >
>? > > >? > > >? > >? ? Here are my observations from summer to now.
Unfortunately, I?? > made >? > > >? > > no observations in October and
early November, so although the?? > comet has >? > > >? > > brightened,
it is not? clear if the brightening occurred over a?? > short or >? > >
>? > > long period. >? > > >? > > >? > > >? > > >? > > >? > > >? > > >?
> >? ? All the best >? > > >? > > >? > > >? > >? ? Peter >? > > >? > >
>? > > >? > > >? > > >? > > >? > > >? > >? ? Type Comet Obs? ? ? ? ? ? ?
? ? ? ? ? date Meth >? > > >? > > Mag Refcat Inst T App Inst F Inst P
Coma User Location >? > > >? > > >? > > >? > >? ? CCD C/2023 Q1
22/12/2024 >? > > >? > > 21:11 Z 15.6 GG C 31.5 8 1260 0.80' CAR06 PGC
>? > > >? > > Observatory Z10, Fregenal de la sierra, Spain >? > > >? >
> >? > > >? > >? ? CCD C/2023 Q1 10/12/2024 >? > > >? > > 03:18 Z 15.9
GG C 31.5 8 1200 0.80' CAR06 PGC >? > > >? > > Observatory Z10, Fregenal
de la sierra, Spain >? > > >? > > >? > > >? > >? ? CCD C/2023 Q1
27/11/2024 >? > > >? > > 02:43 Z 16.1 GG C 31.5 8 1200 0.80' CAR06 PGC
>? > > >? > > Observatory Z10, Fregenal de la sierra, Spain >? > > >? >
> >? > > >? > >? ? CCD C/2023 Q1 04/09/2024 >? > > >? > > 01:48 Z 17.5
GG C 31.5 8 1200 0.40' CAR06 PGC >? > > >? > > Observatory Z10, Fregenal
de la sierra, Spain >? > > >? > > >? > > >? > >? ? CCD C/2023 Q1
16/08/2024 >? > > >? > > 03:21 Z 17.1 GG C 31.5 8 960 0.40' CAR06 PGC >?
> > >? > > Observatory Z10, Fregenal de la sierra, Spain >? > > >? > >
>? > > >? > >? ? CCD C/2023 Q1 05/08/2024 >? > > >? > > 02:33 Z 17.4 GG
C 31.5 8 960 0.40' CAR06 PGC >? > > >? > > Observatory Z10, Fregenal de
la sierra, Spain >? > > >? > > >? > > >? > >? ? CCD C/2023 Q1 16/07/2024
>? > > >? > > 02:52 Z 17.5 GG C 31.5 8 1080 0.40' CAR06 PGC >? > > >? >
> Observatory Z10, Fregenal de la sierra, Spain >? > > >? > > >? > > >?
> >? ? CCD C/2023 Q1 10/07/2024 >? > > >? > > 02:39 Z 17.5 GG C 31.5 8
1200 0.40' CAR06 PGC >? > > >? > > Observatory Z10, Fregenal de la
sierra, Spain >? > > >? > > >? > > >? > > >? > > >? > > >? > > >? > > >?
> > >? > > >? > > >? > > >? > > >? > > >? > > >? > > >? > > >? > >? ?
From: [email protected] <[email protected]> on behalf of?? > Thomas
>? > > >? > > Lehmann via <t.lehmann=[email protected]>
Sent: 26 >? > > >? > > December 2024 22:19 To: [email protected]
<[email protected]> >? > > >? > > Subject: [comets-ml] Unusual
brightening of comet C/2023 Q1 >? > > >? > > >? > > >? > > >? > > >? > >
>? > > >? > >? ? ? According to observations by S. Fritsche and myself
the?? > comet >? > > >? > > C/2023 Q1 has started a sudden brightening
in November.?? > Unfortunately >? > > >? > > our observations are very
sparse due to the bad weather during the?? > last >? > > >? > > two
months. Our data suggest a brightening by 1-2 mag between?? > October >?
> > >? > > 26th and November 30th.? Latest measurement (green channel):
>? > > >? > > 2024-12-23.46 UT, m1=14.1, coma diam. 5'? A more thorough?
> investigation >? > > >? > > by using small aperture measurements is on
the way.? Thanks to?? > all >? > > >? > > contributors for sharing
results and ideas/thoughts to this list.?? > Merry >? > > >? > >
Christmas and best wishes to all of you, Thomas >? > > >? > > >? > > >?
> > >? > > >? > > >? > > >? > > >? > > >? > > >? > > >? > > >? > > >? >
>? ? ? This email and any attachments are intended solely for the?? >
use of >? > > >? > > the named recipients. If you are not the intended
recipient you?? > must not >? > > >? > > use, disclose, copy or
distribute this email or any of its?? > attachments >? > > >? > > and
should notify the sender immediately and delete? this email?? > from >?
> > >? > > your system. UK Research and Innovation (UKRI) has taken
every >? > > >? > > reasonable precaution to minimise risk of this email
or any?? > attachments >? > > >? > > containing viruses or malware but
the recipient should carry out?? > its own >? > > >? > > virus and
malware checks before? opening the attachments. UKRI?? > does not >? > >
>? > > accept any liability for any losses or damages which the
recipient?? > may >? > > >? > > sustain due to presence of any viruses.
>? > > >? > > >? > > >? > > >? > > >? > > >? > > >? > > >? > > >? > > >?
> > >? > > >? > > >? > > >? > > >? > > >? > > >? > > >? > > >? > > >? >
> >? > > >? > > >? > > >? > > >? > > >? > > >? > > >? > >?? >? > >? > >?
> >? > >? >?? >? >? >?? >? >? >? >? >? >? >? >? >? >
|
Hi all,
Last night I observed again from Frasso Sabino (Observatory 157, Rieti, Italy) the "comet" 2015CD60 and it has not only increased in brightness, compared to December 2nd when I realized it was active, but also the tail is better visible and also longer. Now it should be at maximum brightness (passed perihelion a few days ago and almost at minimum distance from the Earth).
Image data: 40x90s, north at the top and east to the left (north has just rotated about 4 degrees to the left), scale 1".24/pixel and field of 32'.3x21'.6. Date 28/12/2024 mean time 23h30m UT.
Mag. Comet with clear filter 16.8, diameter 11" and tail of 1'.3 in PA289°.
Fun fact: 4 asteroids are also visible in the field (and there are 3 more visible but only by adding their movement).
Regards,
Roberto Haver
157 Frasso Sabino
|
Re: Unknown object in M15 image on Nov 27, 2024
Anecdotally, I once created a comet on Tri-X film back in the late 60's.? I was wearing a radium-dial watch in the dark room. :-)? ? Kinda exciting for a minute or two.
On Sun, Dec 29, 2024 at 12:29?PM Thomas Dorman via <drygulch_99= [email protected]> wrote:
Have you checked to see if you may have imaged a venting from a spacecraft or rocket body?? Regards Thomas
On Sunday, December 29, 2024 at 11:18:20 AM CST, John Hart McCue via <red_cerebus= [email protected]> wrote:
Hi Peter,
Thank you so much, that’s very interesting; I had no idea that could happen.?
It was the first image I took with the Seestar and, being new to stacking procedures, I let it proceed without saving the subs. I think the object, if it was real and so faint, probably wouldn’t have shown on the individual subs anyway.
Thanks again, and it shows how much care should be taken to eliminate all the possible vagaries of electronic images.
Best wishes,
John
John,
I think the stacking may have registered a frame incorrectly
causing a faint image of the centre of M15 to appear offset to the
west.
I've blinked the B-27 image with the Dec 20 image and there are
(at least) three bright stars extra on the B-27 image along with
the unknown object but all four objects appear displaced from
bright stars (and M15) as the attached image shows.
Peter
J95
On 29/12/2024 15:11, John Hart McCue via wrote:
[Edited Message Follows]
Hello
all, I'm
a new member, MPC recommended your group. I live near the
North York Moors National Dark Skies Park, northeast UK, and
recently bought a Seestar S50 to help them with outreach. To
familiarise myself with it, I imaged M15 on Nov. 27, 2024. I
didn’t scrutinise the image in detail until 8 Dec., and
noticed the extended object just to the right of the cluster.
The image prefixed A is the stacked 19 min. R filter exposure.
The Seestar’s camera is a Sony IMX462, with a CMOS sensor
which has a resolution of 1920 x 1080 pixels (2 MP). The image
prefixed B is the same stacked image but de-noised with the
Seestar's AI function on Dec. 8. My next clear nights were on
19 and 20 Dec., and I imaged M15 again with approximately the
same length of exposure. The sky transparency on Nov 27 was
slightly better than that on Dec 19 and 20, but there was no
sign of the unknown object. Using
and the Skychart
software (CdC),I estimate the object's J2000 position as 21h
29m 27.9s, +12 deg. 11' 44”, with approximate error 5”, and a
rough magnitude of 16 error 1, though I don’t have a lot of
experience estimating cometary magnitudes. I
web-searched for M15 images, and also searched the British
Astronomical Association's Deep Sky Gallery (of which I am a
member) with no sign of the object so no obvious
identification. I also searched the deep sky databases on the
software Cartes du Ciel (Skychart), again to no avail. I was
observatory code 937 in the northeast of England, but have now
moved house about 15 miles to the east. MPC
have just told me that they could not locate
any known objects at my given position and date and
suggested, as I mentioned, that I post a message to your
group.
MPC said maybe someone can track down archive images of the
region near that date.? Best
wishes for a happy new year, John
|
Re: Unknown object in M15 image on Nov 27, 2024
Have you checked to see if you may have imaged a venting from a spacecraft or rocket body?? Regards Thomas
On Sunday, December 29, 2024 at 11:18:20 AM CST, John Hart McCue via groups.io <red_cerebus@...> wrote:
Hi Peter,
Thank you so much, that’s very interesting; I had no idea that could happen.?
It was the first image I took with the Seestar and, being new to stacking procedures, I let it proceed without saving the subs. I think the object, if it was real and so faint, probably wouldn’t have shown on the individual subs anyway.
Thanks again, and it shows how much care should be taken to eliminate all the possible vagaries of electronic images.
Best wishes,
John
On 29 Dec 2024, at 15:39, Peter Birtwhistle via groups.io <peter@...> wrote:
John,
I think the stacking may have registered a frame incorrectly
causing a faint image of the centre of M15 to appear offset to the
west.
I've blinked the B-27 image with the Dec 20 image and there are
(at least) three bright stars extra on the B-27 image along with
the unknown object but all four objects appear displaced from
bright stars (and M15) as the attached image shows.
Peter
J95
On 29/12/2024 15:11, John Hart McCue via groups.io wrote:
[Edited Message Follows]
Hello
all, I'm
a new member, MPC recommended your group. I live near the
North York Moors National Dark Skies Park, northeast UK, and
recently bought a Seestar S50 to help them with outreach. To
familiarise myself with it, I imaged M15 on Nov. 27, 2024. I
didn’t scrutinise the image in detail until 8 Dec., and
noticed the extended object just to the right of the cluster.
The image prefixed A is the stacked 19 min. R filter exposure.
The Seestar’s camera is a Sony IMX462, with a CMOS sensor
which has a resolution of 1920 x 1080 pixels (2 MP). The image
prefixed B is the same stacked image but de-noised with the
Seestar's AI function on Dec. 8. My next clear nights were on
19 and 20 Dec., and I imaged M15 again with approximately the
same length of exposure. The sky transparency on Nov 27 was
slightly better than that on Dec 19 and 20, but there was no
sign of the unknown object. Using
and the Skychart
software (CdC),I estimate the object's J2000 position as 21h
29m 27.9s, +12 deg. 11' 44”, with approximate error 5”, and a
rough magnitude of 16 error 1, though I don’t have a lot of
experience estimating cometary magnitudes. I
web-searched for M15 images, and also searched the British
Astronomical Association's Deep Sky Gallery (of which I am a
member) with no sign of the object so no obvious
identification. I also searched the deep sky databases on the
software Cartes du Ciel (Skychart), again to no avail. I was
observatory code 937 in the northeast of England, but have now
moved house about 15 miles to the east. MPC
have just told me that they could not locate
any known objects at my given position and date and
suggested, as I mentioned, that I post a message to your
group.
MPC said maybe someone can track down archive images of the
region near that date.? Best
wishes for a happy new year, John
|
Re: Unknown object in M15 image on Nov 27, 2024
Hi Peter,
Thank you so much, that’s very interesting; I had no idea that could happen.?
It was the first image I took with the Seestar and, being new to stacking procedures, I let it proceed without saving the subs. I think the object, if it was real and so faint, probably wouldn’t have shown on the individual subs anyway.
Thanks again, and it shows how much care should be taken to eliminate all the possible vagaries of electronic images.
Best wishes,
John
toggle quoted message
Show quoted text
On 29 Dec 2024, at 15:39, Peter Birtwhistle via groups.io <peter@...> wrote:
John,
I think the stacking may have registered a frame incorrectly
causing a faint image of the centre of M15 to appear offset to the
west.
I've blinked the B-27 image with the Dec 20 image and there are
(at least) three bright stars extra on the B-27 image along with
the unknown object but all four objects appear displaced from
bright stars (and M15) as the attached image shows.
Peter
J95
On 29/12/2024 15:11, John Hart McCue via groups.io wrote:
[Edited Message Follows]
Hello
all, I'm
a new member, MPC recommended your group. I live near the
North York Moors National Dark Skies Park, northeast UK, and
recently bought a Seestar S50 to help them with outreach. To
familiarise myself with it, I imaged M15 on Nov. 27, 2024. I
didn’t scrutinise the image in detail until 8 Dec., and
noticed the extended object just to the right of the cluster.
The image prefixed A is the stacked 19 min. R filter exposure.
The Seestar’s camera is a Sony IMX462, with a CMOS sensor
which has a resolution of 1920 x 1080 pixels (2 MP). The image
prefixed B is the same stacked image but de-noised with the
Seestar's AI function on Dec. 8. My next clear nights were on
19 and 20 Dec., and I imaged M15 again with approximately the
same length of exposure. The sky transparency on Nov 27 was
slightly better than that on Dec 19 and 20, but there was no
sign of the unknown object. Using
and the Skychart
software (CdC),I estimate the object's J2000 position as 21h
29m 27.9s, +12 deg. 11' 44”, with approximate error 5”, and a
rough magnitude of 16 error 1, though I don’t have a lot of
experience estimating cometary magnitudes. I
web-searched for M15 images, and also searched the British
Astronomical Association's Deep Sky Gallery (of which I am a
member) with no sign of the object so no obvious
identification. I also searched the deep sky databases on the
software Cartes du Ciel (Skychart), again to no avail. I was
observatory code 937 in the northeast of England, but have now
moved house about 15 miles to the east. MPC
have just told me that they could not locate
any known objects at my given position and date and
suggested, as I mentioned, that I post a message to your
group.
MPC said maybe someone can track down archive images of the
region near that date.? Best
wishes for a happy new year, John
<B-27Nov2024+Dec20M15.png>
|
Re: Unknown object in M15 image on Nov 27, 2024
John,
I think the stacking may have registered a frame incorrectly
causing a faint image of the centre of M15 to appear offset to the
west.
I've blinked the B-27 image with the Dec 20 image and there are
(at least) three bright stars extra on the B-27 image along with
the unknown object but all four objects appear displaced from
bright stars (and M15) as the attached image shows.
Peter
J95
On 29/12/2024 15:11, John Hart McCue via groups.io wrote:
toggle quoted message
Show quoted text
[Edited Message Follows]
Hello
all,
I'm
a new member, MPC recommended your group. I live near the
North York Moors National Dark Skies Park, northeast UK, and
recently bought a Seestar S50 to help them with outreach. To
familiarise myself with it, I imaged M15 on Nov. 27, 2024. I
didn’t scrutinise the image in detail until 8 Dec., and
noticed the extended object just to the right of the cluster.
The image prefixed A is the stacked 19 min. R filter exposure.
The Seestar’s camera is a Sony IMX462, with a CMOS sensor
which has a resolution of 1920 x 1080 pixels (2 MP). The image
prefixed B is the same stacked image but de-noised with the
Seestar's AI function on Dec. 8. My next clear nights were on
19 and 20 Dec., and I imaged M15 again with approximately the
same length of exposure. The sky transparency on Nov 27 was
slightly better than that on Dec 19 and 20, but there was no
sign of the unknown object.
Using
and the Skychart
software (CdC),I estimate the object's J2000 position as 21h
29m 27.9s, +12 deg. 11' 44”, with approximate error 5”, and a
rough magnitude of 16 error 1, though I don’t have a lot of
experience estimating cometary magnitudes.
I
web-searched for M15 images, and also searched the British
Astronomical Association's Deep Sky Gallery (of which I am a
member) with no sign of the object so no obvious
identification. I also searched the deep sky databases on the
software Cartes du Ciel (Skychart), again to no avail. I was
observatory code 937 in the northeast of England, but have now
moved house about 15 miles to the east.
MPC
have just told me that they could not locate
any known objects at my given position and date and
suggested, as I mentioned, that I post a message to your
group.
MPC said maybe someone can track down archive images of the
region near that date.?
Best
wishes for a happy new year,
John
|
Unknown object in M15 image on Nov 27, 2024
Hello all,
I'm a new member, MPC recommended your group. I live near the North York Moors National Dark Skies Park, northeast UK, and recently bought a Seestar S50 to help them with outreach. To familiarise myself with it, I imaged M15 on Nov. 27, 2024. I didn’t scrutinise the image in detail until 8 Dec., and noticed the extended object just to the right of the cluster. The image prefixed A is the stacked 19 min. R filter exposure. The Seestar’s camera is a Sony IMX462, with a CMOS sensor which has a resolution of 1920 x 1080 pixels (2 MP). The image prefixed B is the same stacked image but de-noised with the Seestar's AI function on Dec. 8. My next clear nights were on 19 and 20 Dec., and I imaged M15 again with approximately the same length of exposure. The sky transparency on Nov 27 was slightly better than that on Dec 19 and 20, but there was no sign of the unknown object.
Using and the Skychart software (CdC),I estimate the object's J2000 position as 21h 29m 27.9s, +12 deg. 11' 44”, with approximate error 5”, and a rough magnitude of 16 error 1, though I don’t have a lot of experience estimating cometary magnitudes.
I web-searched for M15 images, and also searched the British Astronomical Association's Deep Sky Gallery (of which I am a member) with no sign of the object so no obvious identification. I also searched the deep sky databases on the software Cartes du Ciel (Skychart), again to no avail. I was observatory code 937 in the northeast of England, but have now moved house about 15 miles to the east.
MPC have just told me that they could not locate any known objects at my given position and date and suggested, as I mentioned, that I post a message to your group. MPC said maybe someone can track down archive images of the region near that date.?
Best wishes for a happy new year,
John
|
Denis Buczynski
John Hart McCue
