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C/2024 G3 (ATLAS)
开云体育Hi All: Astronaut Don Pettit captured a nice image of C/2024 G3 (ATLAS) from ISS earlier today prior to one of his local sunrises. At the time of his shot (1/9 12:59 UT, Nikon Z9 lens, f/1.2, 1/60th of second) the solar elongation was only 11 degrees. I’ll ask Don if I can share it here. Any estimate of how bright it should be right now? There are Sagittarius reference stars in his image (mu, lambda, phi, delta, gamma, eta) plus Mercury and it is far brighter than any of them. (Mercury currently -0.4, and the comet looks at least 2 or 3 magnitudes brighter).? --Rob |
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Hi Rob,
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Can you ask him if he can take/share some raw images so we can do some photometric measurements? It was about mag 0, although when I observed it on Jan 8 18:40 UT it seemed to have faded just slightly. Terry On Friday 10 January 2025 at 08:24:54 am AEST, Matson, Rob D. via groups.io <robert.d.matson@...> wrote:
?? Hi All: Astronaut Don Pettit captured a nice image of C/2024 G3 (ATLAS) from ISS earlier today prior to one of his local sunrises. At the time of his shot (1/9 12:59 UT, Nikon Z9 lens, f/1.2, 1/60th of second) the solar elongation was only 11 degrees. I’ll ask Don if I can share it here. Any estimate of how bright it should be right now? There are Sagittarius reference stars in his image (mu, lambda, phi, delta, gamma, eta) plus Mercury and it is far brighter than any of them. (Mercury currently -0.4, and the comet looks at least 2 or 3 magnitudes brighter).? --Rob |
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Rob,
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COBS is a good source of info on comet magnitudes: As Terry says, the latest ground based observations have it around zero. Having the raw files from Don would be great if possible so we could do some photometry. Nick. On 09/01/2025 22:24, Matson, Rob D. via groups.io wrote:
Hi All: Astronaut Don Pettit captured a nice image of C/2024 G3 (ATLAS) from ISS earlier today prior to one of his local sunrises. At the time of his shot (1/9 12:59 UT, Nikon Z9 lens, f/1.2, 1/60th of second) the solar elongation was only 11 degrees. I'll ask Don if I can share it here. Any estimate of how bright it should be right now? There are Sagittarius reference stars in his image (mu, lambda, phi, delta, gamma, eta) plus Mercury and it is far brighter than any of them. (Mercury currently -0.4, and the comet looks at least 2 or 3 magnitudes brighter). --Rob |
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Hi Terry -- I put in a request to Don to see if he can provide a raw image or images for photometry... --Rob
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-----Original Message-----
From: [email protected] <[email protected]> On Behalf Of terryjlovejoy via groups.io Sent: Thursday, January 9, 2025 2:30 PM To: [email protected] Subject: EXTERNAL: Re: [comets-ml] C/2024 G3 (ATLAS) CAUTION: This email originated from outside of Leidos. Be cautious when clicking or opening content. Hi Rob, Can you ask him if he can take/share some raw images so we can do some photometric measurements? It was about mag 0, although when I observed it on Jan 8 18:40 UT it seemed to have faded just slightly. Terry On Friday 10 January 2025 at 08:24:54 am AEST, Matson, Rob D. via groups.io <robert.d.matson@...> wrote: Hi All: Astronaut Don Pettit captured a nice image of C/2024 G3 (ATLAS) from ISS earlier today prior to one of his local sunrises. At the time of his shot (1/9 12:59 UT, Nikon Z9 lens, f/1.2, 1/60th of second) the solar elongation was only 11 degrees. I’ll ask Don if I can share it here. Any estimate of how bright it should be right now? There are Sagittarius reference stars in his image (mu, lambda, phi, delta, gamma, eta) plus Mercury and it is far brighter than any of them. (Mercury currently -0.4, and the comet looks at least 2 or 3 magnitudes brighter). --Rob |
开云体育If it sticks to 7.1 + 11.7 log r it will be around -2. It is likely to be within a magnitude of that. ? Regards, ? Jonathan Shanklin BAA Comet Section visual observations co-ordinator
? ? ? From: [email protected] <[email protected]>
On Behalf Of Matson, Rob D. via groups.io
Sent: Thursday, January 9, 2025 10:25 PM To: [email protected] Subject: [comets-ml] C/2024 G3 (ATLAS) ? Hi All: Astronaut Don Pettit captured a nice image of C/2024 G3 (ATLAS) from ISS earlier today prior to one of his local sunrises. At the time of his shot (1/9 12:59 UT, Nikon Z9 lens, f/1.2, 1/60th of second) the solar elongation was only 11 degrees. I’ll ask Don if I can share it here. Any estimate of how bright it should be right now? There are Sagittarius reference stars in his image (mu, lambda, phi, delta, gamma, eta) plus Mercury and it is far brighter than any of them. (Mercury currently -0.4, and the comet looks at least 2 or 3 magnitudes brighter).? --Rob 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. |
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I've just managed to image C/2024 G3 (ATLAS) in daylight from Chelmsford, UK (latitude 51.5N) using a 90mm refractor and an ASI1600 camera. The attached image is a differenced stack of two lots of 20x700us frames offset in declination by 23 arcmin. You can see two versions of the comet, one in positive and one in negative. The orientation is N up and the elongation is currently 7.9 deg.
The sun and comet were both low down and the sky rather hazy so I was surprised to get such a strong image. The comet must be pretty bright. I have images of Venus taken with the same settings just before so I should be able to estimate the magnitude with an appropriate correction for the different altutude. Nick. |
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Sorry, forgot to include details. The image was taken at 1432 UTC on 2025-01-11. At that time both comet and sun were 10 deg above my horizon.
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Nick. On 11/01/2025 15:02, Nick James wrote:
I've just managed to image C/2024 G3 (ATLAS) in daylight from Chelmsford, UK (latitude 51.5N) using a 90mm refractor and an ASI1600 camera. The attached image is a differenced stack of two lots of 20x700us frames offset in declination by 23 arcmin. You can see two versions of the comet, one in positive and one in negative. The orientation is N up and the elongation is currently 7.9 deg. |
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Nick,
this is really great, great images, thank you. I might try it visually tomorrow as we have sunny skies predicted. Should gain maybe 2 mag in the next 24-48 hours. Maik -- "One cannot discover comets lying in bed." * Lewis Swift ________________________________________________________________________ *** @skymorph.bsky.social |
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Maik,
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Good luck tomorrow. I know you are very experienced but be careful. I'm only risking a camera, not my eyes! I've processed the full video now and the result is here: I've tried to estimate the magnitude by measuring the intensity in a 40 arcsec diameter aperture and comparing it to a video of Venus taken just before the comet observation using the same settings. Assuming Venus is -4.6 and using a correction of 1.0 mag for differential altitude (Venus was at 29 deg, the comet at 10 deg) I get -0.8. That doesn't really seem bright enough given how prominent the comet is on the image but that is what I get! Nick. On 11/01/2025 15:15, Maik Meyer wrote:
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That's consistent with my initial crude estimate this morning of -0.5 (measured against Mercury earlier at a similar airmass). The comet's easy visibility is because its coma is so compact, giving it a very high surface brightness now already comparable to C/2023 A3 at its peak. Qicheng
On Saturday, January 11, 2025 at 11:20:52 a.m. MST, Nick James <comets@...> wrote:
Maik, Good luck tomorrow. I know you are very experienced but be careful. I'm only risking a camera, not my eyes! I've processed the full video now and the result is here: I've tried to estimate the magnitude by measuring the intensity in a 40 arcsec diameter aperture and comparing it to a video of Venus taken just before the comet observation using the same settings. Assuming Venus is -4.6 and using a correction of 1.0 mag for differential altitude (Venus was at 29 deg, the comet at 10 deg) I get -0.8. That doesn't really seem bright enough given how prominent the comet is on the image but that is what I get! Nick. On 11/01/2025 15:15, Maik Meyer wrote: > Nick, > > this is really great, great images, thank you. I might try it visually > tomorrow as we have sunny skies predicted. Should gain maybe 2 mag in > the next 24-48 hours. > > Maik |
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I also just took a very quick look at the short exposure (minimally saturated) LASCO C3 data as well from Jan 11 ~12 UT. It's not possible to isolate the brightness of the coma alone, as that's <1 px in size in this camera, but within a 7 px ~ 6.5 arcmin diameter aperture, it was at V mag ~ -1.3. Note that the comet is now passing behind the (out of focus) pylon that holds the occulter in place, and the vignetting by this pylon is causing the saturation spikes in the synoptic C3 Clear data to shrink (i.e., the comet itself is not fading despite becoming less saturated on the detector). Qicheng
On Saturday, January 11, 2025 at 11:33:02 a.m. MST, Qicheng Zhang via groups.io <qzalaska@...> wrote:
That's consistent with my initial crude estimate this morning of -0.5 (measured against Mercury earlier at a similar airmass). The comet's easy visibility is because its coma is so compact, giving it a very high surface brightness now already comparable to C/2023 A3 at its peak. Qicheng
On Saturday, January 11, 2025 at 11:20:52 a.m. MST, Nick James <comets@...> wrote:
Maik, Good luck tomorrow. I know you are very experienced but be careful. I'm only risking a camera, not my eyes! I've processed the full video now and the result is here: I've tried to estimate the magnitude by measuring the intensity in a 40 arcsec diameter aperture and comparing it to a video of Venus taken just before the comet observation using the same settings. Assuming Venus is -4.6 and using a correction of 1.0 mag for differential altitude (Venus was at 29 deg, the comet at 10 deg) I get -0.8. That doesn't really seem bright enough given how prominent the comet is on the image but that is what I get! Nick. On 11/01/2025 15:15, Maik Meyer wrote: > Nick, > > this is really great, great images, thank you. I might try it visually > tomorrow as we have sunny skies predicted. Should gain maybe 2 mag in > the next 24-48 hours. > > Maik |
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Nick, that's an excellent image and I very much trust the brightness estimates
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from you and Qicheng. Don Pettit's beautiful image from space might not be appropriate to compare the brightness of mercury and the comet as both of them might well be saturated with mercury at much larger amount. In this case the larger extent of the head of the comet in comparison to the (point-like) planet only gives an illusion of much brighter appearance. Thomas Am Sat, 11 Jan 2025 20:21:51 +0000 (UTC) |
开云体育The magnitudes I see this morning definitely mean that a visual daytime sighting today will be impossible. Since the maximum should happen over the coming 48 hours the question will be if it reaches -4 mag or brighter on the 13th or 14th. Assuming that it is -1.5 this morning I think this won't be possible if the comet behaves normally.Maik Sent from my mobile 11.01.2025 19:20:56 Nick James <comets@...>:
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I was processing some FITS images and I saw additional tail in C3 Orange filter, which is really faint in images taken without any filters. Is it ordinary tail or a sodium tail? Temat: Re: [comets-ml] C/2024 G3 (ATLAS) Data: 2025-01-12 10:06 Nadawca: "Maik Meyer" <maik@...> Adresat: [email protected];
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With high confidence we believe we observed?C/2024 G3 mid-morning naked eye? using? the roof of our house? to block the sun? and than using a polarizing filter than a Svbony IR pass 685nm filter.? If we had to give a magnitude guess some where around -3.5. It is much like trying to observe Venus just as it? is making daylight naked eye visibility not at it brightest. Believe it is best in?Svbony IR pass 685nm filter Regards Thomas Dorman Ozark Mountains USA
On Sunday, January 12, 2025 at 01:25:56 PM CST, K. Ly via groups.io <1523022.alt@...> wrote:
Hi all,
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Someone from Saji Observatory reported a possible fragment 4.5 arcseconds south of C/2024 G3, detected with a 103 cm telescope. Can somebody confirm?
https://x.com/sajiastropark/status/1878267812893913493
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K
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开云体育I tried around 13:30 UT (14:30 local) with 10x50's also using a roof as a shield. A lot of moisture in the air and passing clouds. Didn't see anything and would make it fainter that -4 mag. If weather co-operates I'll give it another try tomorrow.Maik Sent from my mobile 12.01.2025 20:49:33 Thomas Dorman via groups.io <drygulch_99@...>:
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We have blue skies here believe the trick is getting a filter that give high contrast against the blue sky and the glare of the sun. Regards Thomas Dorman.
On Sunday, January 12, 2025 at 01:54:52 PM CST, Maik Meyer <maik@...> wrote:
I tried around 13:30 UT (14:30 local) with 10x50's also using a roof as a shield. A lot of moisture in the air and passing clouds. Didn't see anything and would make it fainter that -4 mag. If weather co-operates I'll give it another try tomorrow.
Maik Sent from my mobile 12.01.2025 20:49:33 Thomas Dorman via groups.io <drygulch_99@...>:
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Nucleus is saturated in the orange filter in LASCO C3.
And the tail structure looks gorgeous! On Sat, Jan 11, 2025 at 12:09?PM Nick James via groups.io <comets@...> wrote:
-- :Wandeclayt: www.ceuprofundo.com instagram: @ceuprofundo twitter: @ceuprofundo facebook: Céu Profundo Astronomia |
K. Ly
Wandeclayt
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