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Hello happy comet enthousiasts !
I was performing some photometry on a variable star (Hip10272, in Aries) in some TICA TESScuts, sector 58, when I came upon a quite nice comet slowly crossing the FOV, in a corner of the images. I did a quick search using Patrick Chevalley's CdC, but could not find any valuable comet candidate to match this beauty.
This comet had a condensed head, about 60'', and maybe a 15' tail, all in all.
I did a photometry in a 1.5 pixel around the centroid of the coma, and get a mean value of 15.32 mag on 74 sub images, so in a 30'' circle, using AIJ. This coma magnitude is in pseudo V, or CV. The mag of the comps stars were in V, but I've some doubts about the original bandpass of the TESS data.
I managed to found a FOV where the comet is traveling dead in the center of the images, and releved an (approximative) astrometric position when the comet just crossed the right center of the FOV, unfortunatelly in front of a mag 13 star.
slice/date (BJD)/ RA/ DEC
7276 2459899.584 021203.4 +234004.3
The TICA sector 58 can be downloaded from here :
If you enter the position 33.133098 23.671662, you'll download the same FOV than mine.
Here are a few images.
Any advice on how to find the name of this comet is welcome.? Thanx in advance.
Clear skies, Christophe
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Hello Christophe, this is P/2022 L3 (ATLAS). Magnitude fits nicely. You may use Regards Maik I was performing some photometry on a variable star (Hip10272, in Aries) in some TICA TESScuts, sector 58, when I came upon a quite nice comet slowly crossing the FOV, in a corner of the images.
I did a quick search using Patrick Chevalley's CdC, but could not find any valuable comet candidate to match this beauty.
This comet had a condensed head, about 60'', and maybe a 15' tail, all in all.
I did a photometry in a 1.5 pixel around the centroid of the coma, and get a mean value of 15.32 mag on 74 sub images, so in a 30'' circle, using AIJ. This coma magnitude is in pseudo V, or CV. The mag of the comps stars were in V, but I've some doubts about the original bandpass of the TESS data.
I managed to found a FOV where the comet is traveling dead in the center of the images, and releved an (approximative) astrometric position when the comet just crossed the right center of the FOV, unfortunatelly in front of a mag 13 star.
slice/date (BJD)/ RA/ DEC
7276 2459899.584 021203.4 +234004.3
The TICA sector 58 can be downloaded from here :
<>
If you enter the position 33.133098 23.671662, you'll download the same FOV than mine.
Here are a few images.
Any advice on how to find the name of this comet is welcome.
Thanx in advance.-- "One cannot discover comets lying in bed." * Lewis Swift ________________________________________________________________________ *** @skymorph.bsky.social
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Hi Christophe and Maik,
I was about to reply that this is C/2022 S4 (Lemmon) which is several magnitudes too faint (close to magnitude 20) but passes over the exact same part of sky (down to the arcsecond) just a few days later. I was used to TESS comet discoveries overestimating the magnitudes by several levels and so was surprisingly ready to believe that a 20th magnitude comet would look like this.
~Sam
On Sunday, December 29, 2024 at 04:33:07 AM EST, Maik Meyer <maik@...> wrote:
Hello Christophe,
this is P/2022 L3 (ATLAS).
Magnitude fits nicely.
You may use
Regards
Maik
> I was performing some photometry on a variable star (Hip10272, in Aries) in some TICA TESScuts, sector 58, when I came
> upon a quite nice comet slowly crossing the FOV, in a corner of the images.
> I did a quick search using Patrick Chevalley's CdC, but could not find any valuable comet candidate to match this beauty.
>
> This comet had a condensed head, about 60'', and maybe a 15' tail, all in all.
> I did a photometry in a 1.5 pixel around the centroid of the coma, and get a mean value of 15.32 mag on 74 sub images,
> so in a 30'' circle, using AIJ. This coma magnitude is in pseudo V, or CV. The mag of the comps stars were in V, but
> I've some doubts about the original bandpass of the TESS data.
>
> I managed to found a FOV where the comet is traveling dead in the center of the images, and releved an (approximative)
> astrometric position when the comet just crossed the right center of the FOV, unfortunatelly in front of a mag 13 star.
>
> slice/date (BJD)/ RA/ DEC
>
> 7276 2459899.584 021203.4 +234004.3
>
> The TICA sector 58 can be downloaded from here :
> <>
>
> If you enter the position 33.133098 23.671662, you'll download the same FOV than mine.
>
> Here are a few images.
>
> Any advice on how to find the name of this comet is welcome.
> Thanx in advance.--
"One cannot discover comets lying in bed." * Lewis Swift
________________________________________________________________________
*** @skymorph.bsky.social
|
Hi Christophe,
Using a geocentric Horizons ephemeris, Comet P/2022 L3 (Atlas) was
at 02 12 03.40 +23 40 42.1 on 2022 11 16.685 UTC, quite close to
the position you've given below.
Peter
J95
On 29/12/2024 09:25, cmltb612 via groups.io wrote:
toggle quoted message
Show quoted text
Hello
happy comet enthousiasts !
I
was performing some photometry on a variable star (Hip10272, in
Aries) in some TICA TESScuts, sector 58, when I came upon a
quite nice comet slowly crossing the FOV, in a corner of the
images.
I
did a quick search using Patrick Chevalley's CdC, but could not
find any valuable comet candidate to match this beauty.
This
comet had a condensed head, about 60'', and maybe a 15' tail,
all in all.
I
did a photometry in a 1.5 pixel around the centroid of the coma,
and get a mean value of 15.32 mag on 74 sub images, so in a 30''
circle, using AIJ. This coma magnitude is in pseudo V, or CV.
The mag of the comps stars were in V, but I've some doubts about
the original bandpass of the TESS data.
I
managed to found a FOV where the comet is traveling dead in the
center of the images, and releved an (approximative) astrometric
position when the comet just crossed the right center of the
FOV, unfortunatelly in front of a mag 13 star.
slice/date
(BJD)/ RA/ DEC
7276
2459899.584 021203.4 +234004.3
The
TICA sector 58 can be downloaded from here :
If
you enter the position 33.133098 23.671662, you'll
download the same FOV than mine.
Here
are a few images.
Any
advice on how to find the name of this comet is welcome.?
Thanx
in advance.
Clear
skies,
Christophe
|
Hello dear,
That's it ! Comet 2022 L3 Atlas,
Thank you Maik, Sam and Peter,
Christophe
Le dimanche 29 décembre 2024 à 10:42, Peter Birtwhistle via groups.io <peter@...> a écrit?:
Hi Christophe,
Using a geocentric Horizons ephemeris, Comet P/2022 L3 (Atlas) was
at 02 12 03.40 +23 40 42.1 on 2022 11 16.685 UTC, quite close to
the position you've given below.
Peter
J95
On 29/12/2024 09:25, cmltb612 via groups.io wrote:
Hello
happy comet enthousiasts !
I
was performing some photometry on a variable star (Hip10272, in
Aries) in some TICA TESScuts, sector 58, when I came upon a
quite nice comet slowly crossing the FOV, in a corner of the
images.
I
did a quick search using Patrick Chevalley's CdC, but could not
find any valuable comet candidate to match this beauty.
This
comet had a condensed head, about 60'', and maybe a 15' tail,
all in all.
I
did a photometry in a 1.5 pixel around the centroid of the coma,
and get a mean value of 15.32 mag on 74 sub images, so in a 30''
circle, using AIJ. This coma magnitude is in pseudo V, or CV.
The mag of the comps stars were in V, but I've some doubts about
the original bandpass of the TESS data.
I
managed to found a FOV where the comet is traveling dead in the
center of the images, and releved an (approximative) astrometric
position when the comet just crossed the right center of the
FOV, unfortunatelly in front of a mag 13 star.
slice/date
(BJD)/ RA/ DEC
7276
2459899.584 021203.4 +234004.3
The
TICA sector 58 can be downloaded from here :
If
you enter the position 33.133098 23.671662, you'll
download the same FOV than mine.
Here
are a few images.
Any
advice on how to find the name of this comet is welcome.
Thanx
in advance.
Clear
skies,
Christophe
|
On 12/29/24 04:33, Maik Meyer wrote:> You may use With the minor note that, because this is a spacecraft-based observation, you'll have to tell MPC where the spacecraft was at the time of the observation. This tool may simplify that task : (Though if you're just looking for an identification, you can probably get away with lying and saying that it was a geocentric observation. Apogee is only about at the distance of the moon.) The TESS observations I've seen tend to be oddly bad in the astrometry; several-arcsecond mean errors are normal. And recently, my Sat_ID tool logged errors for TESS observations that made me wonder if there might be timing issues as well : As noted there, the astrometric error issues may just be due to these being wide-field images and needing better correction than your average image. In any case... I've yet to see really good astrometry come from TESS. (Photometry, at least after going through the 'official' TESS pipeline, is presumably lovely stuff, or they wouldn't be finding exoplanets with it. Though that's the stellar photometry; photometry of fuzzy or moving objects may not be so great.) -- Bill Regards
Maik
I was performing some photometry on a variable star (Hip10272, in Aries) in some TICA TESScuts, sector 58, when I came upon a quite nice comet slowly crossing the FOV, in a corner of the images.
I did a quick search using Patrick Chevalley's CdC, but could not find any valuable comet candidate to match this beauty.
This comet had a condensed head, about 60'', and maybe a 15' tail, all in all.
I did a photometry in a 1.5 pixel around the centroid of the coma, and get a mean value of 15.32 mag on 74 sub images, so in a 30'' circle, using AIJ. This coma magnitude is in pseudo V, or CV. The mag of the comps stars were in V, but I've some doubts about the original bandpass of the TESS data.
I managed to found a FOV where the comet is traveling dead in the center of the images, and releved an (approximative) astrometric position when the comet just crossed the right center of the FOV, unfortunatelly in front of a mag 13 star.
slice/date (BJD)/ RA/ DEC
7276 2459899.584 021203.4 +234004.3
The TICA sector 58 can be downloaded from here :
<>
If you enter the position 33.133098 23.671662, you'll download the same FOV than mine.
Here are a few images.
Any advice on how to find the name of this comet is welcome.
Thanx in advance.-- "One cannot discover comets lying in bed." * Lewis Swift
________________________________________________________________________
*** @skymorph.bsky.social
|
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
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