Re: Comet C/2025 F2 (SWAN) in the bright Moonlight
Heavy haze on the morning of 2025 April 21, managed to get only one fair image of the comet at an altitude of 5 degrees. 2025 F2 was magnitude G=9.9 as calculated from 4x20 second images in an aperture diameter of 3'. Nothing in the hazy image suggested much change from yesterday morning
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Re: C/2025 F2 (SWAN) from June Lake, CA
Thanks for sharing the link, Dan, and congrats on making APoD! Very nice shot from June Lake when the comet was looking a lot healthier than it is now!? --Rob
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From: [email protected] <[email protected]>
On Behalf Of Dan Bartlett via groups.io
Sent: Friday, April 18, 2025 11:15 AM
To: [email protected]
Subject: EXTERNAL: Re: [comets-ml] C/2025 F2 (SWAN)
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It appears NASA recognizes the hard work of those who discovered this comet in todays APOD.
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Re: SWAN disintegration: statistically expectable or not?
This comet had? an aphel distance of around 6 thousand AU (my calculation). This is well inside the Oort cloud, which is assumed to extend from 1 thousand to 100 thousand AU.?
Orbital changes by a close encounter may have deflected the orbit to the inner solar system. The comet may dynamical new. The light curve gives no clear answer here.
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Uwe Pilz, Leipzig, Germany.
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Re: SWAN disintegration: statistically expectable or not?
Hello Adrien,
For dynamically new comets we always meet the main body, however for dynamically older comets, we can also meet fragments separated from main body revolution before. Such fragments usually disintegrate next time they approach to Sun (see example of comet C/1988 A1 Liller and C/1996 Q1 Tabur). For orbital period in tens of thousands years, the distance between main component and fragment can be large, in hundreds years, so we most likely never recorded the main component before. This is most plausible scenario for actual case.
Best regards,
Jakub ?ern?
厂迟á丑苍辞耻迟
Hi all,
Statistical question: given that this (non-sungrazing) comet seems to not be new (barycentric orbital period in the 30~80 thousand years at epoch 1900), i.e. its disintegration could supposingly have happened at any other approach before or after the current one, is this seeming disintegration at this specific approach a statistically unexpectable event (i.e. expectable lifetime / number of known similarly-long-period comets >> orbital period), or is it statistically not unlikely (i.e. expectable lifetime / number... << orbital period) -- and even more, unlikely or not to happen within "modern astronomy" (i.e. expectable lifetime / number... >> or << centuries)?
Thank you in advance for your help.
Adrien
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Re: 回复： [comets-ml] Comet C/2025 F2 (SWAN) > 2025.04.20
Mike, I can clearly see that the star trails are much sharper than the core of the comet, which suggests that there is not much left of the comets nucleus.?
Clear Skies,
Chris Schur
Schur's Web Portal: http://www.schursastrophotography.com
On Sunday, April 20, 2025 at 05:43:04 PM MST, Mike Olason via groups.io <molason@...> wrote:
Comet C/2025 F2 (SWAN) on the morning of 2025 April 20 was magnitude 9.8, in these stacked images there does not appear to be a central bright area in the coma, but the images were collected at a low altitude of 6 to 7 degrees with a 56% illuminated Moon in the sky so atmospheric distortion could be masking a brighter area. Would have expected a bigger dust tail if the comet was disintegrating unless the comet is very small.
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Re: Comet C/2025 F2 (SWAN) in the bright Moonlight
Comet C/2025 F2 (SWAN) on the morning of 2025 April 20 was magnitude 9.8, in these stacked images there does not appear to be a central bright area in the coma, but the images were collected at a low altitude of 6 to 7 degrees with a 56% illuminated Moon in the sky so atmospheric distortion could be masking a brighter area. Would have expected a bigger dust tail if the comet was disintegrating unless the comet is very small.
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Re: 回复： [comets-ml] Comet C/2025 F2 (SWAN) > 2025.04.20
Comet C/2025 F2 (SWAN) on the morning of 2025 April 20 was magnitude 9.8, in these stacked images there does not appear to be a central bright area in the coma, but the images were collected at a low altitude of 6 to 7 degrees with a 56% illuminated Moon in the sky so atmospheric distortion could be masking a brighter area. Would have expected a bigger dust tail if the comet was disintegrating unless the comet is very small.
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SWAN disintegration: statistically expectable or not?
Hi all,
Statistical question: given that this (non-sungrazing) comet seems to not be new (barycentric orbital period in the 30~80 thousand years at epoch 1900), i.e. its disintegration could supposingly have happened at any other approach before or after the current one, is this seeming disintegration at this specific approach a statistically unexpectable event (i.e. expectable lifetime / number of known similarly-long-period comets >> orbital period), or is it statistically not unlikely (i.e. expectable lifetime / number... << orbital period) -- and even more, unlikely or not to happen within "modern astronomy" (i.e. expectable lifetime / number... >> or << centuries)?
Thank you in advance for your help.
Adrien
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Comet C/2023 Lemmon H5 on 4/19/25
Comet C/2023 Lemmon H5, April 19 starting at 11:00 pm MST (06:00 UT 4/20/25), 10" f/3.9 Newtonian Astrograph, LRGB = 1h, Atik16200 CCD, Payson,AZ
I put a blow up of the central image in this frame because this comet is so tiny!
Clear Skies,
Chris Schur
Schur's Web Portal: http://www.schursastrophotography.com
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Re: 回复： [comets-ml] Comet C/2025 F2 (SWAN) > 2025.04.20
Most definitely, reminiscent of a faint Kreutz in LASCO C2, a fuzzy nuclear region means this feature is a rubble pile of not destroyed already.
After all, the nucleus seems to have gone totally. Thank you Danilo for your usefull photo.
Cheers, Erik
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Re: 回复： [comets-ml] Comet C/2025 F2 (SWAN) > 2025.04.20
After all, the nucleus seems to have gone totally. Thank you Danilo for your usefull photo.
Cheers, Erik
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Re: 回复： [comets-ml] Comet C/2025 F2 (SWAN) > 2025.04.20
Hi,
this is the 100% crop without any processing
Danilo
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Re: Comet C/2025 F2 (SWAN) in the bright Moonlight
On a nice clear morning of 2025 April 20 UT, Comet C/2025 F2 (SWAN) was magnitude 9.8 as calculated from 4x20 second images thru a green filter in an aperture diameter of 3'. The comet coma was 2.5' wide, the tail was 2' long at a position angle of 313 degrees from the comet coma. The comet was at an altitude of 5.5 degrees just before the beginning of twilight and the Moon was only 56% illuminated. The ion tail is gone and the dust tail is not very impressive. When looking at the comet's magnitude, the comet has been very quiet since April 9 when it was magnitude 9.3, fading slowly as it approaches perihelion in its orbit on May 1.
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Re: Comet C/2025 F2 (SWAN) > 2025.04.20
On a nice clear morning of 2025 April 20 UT, Comet C/2025 F2 (SWAN) was magnitude 9.8 as calculated from 4x20 second images thru a green filter in an aperture diameter of 3'. The comet coma was 2.5' wide, the tail was 2' long at a position angle of 313 degrees from the comet coma. The comet was at an altitude of 5.5 degrees just before the beginning of twilight and the Moon was only 56% illuminated. The ion tail is gone and the dust tail is not very impressive. When looking at the comet's magnitude, the comet has been very quiet since April 9 when it was magnitude 9.3, fading slowly as it approaches perihelion in its orbit on May 1.
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回复： [comets-ml] Comet C/2025 F2 (SWAN) > 2025.04.20
Danilo: You can try cropping the high-resolution image of the local region near the comet.
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------------------?原始邮件?------------------ 发件人: "comets-ml" <BigBangObservatory@...>; 发送时间:?2025年4月20日(星期天) 下午3:45 主题:?Re: [comets-ml] Comet C/2025 F2 (SWAN) > 2025.04.20
Sorry, but the photos posted in the list are rescaled to a maximum of 1024 pixels? I tried with the last image (1920 pixels) and it was reduced to 1024pixels
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Il giorno dom 20 apr 2025 alle ore 09:37 Danilo Pivato via groups.io
<BigBangObservatory@...> ha scritto:
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> Hi, I'm attaching the image again with higher resolution
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> Best,
>
> Danilo
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>
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>
>
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Re: Comet C/2025 F2 (SWAN) > 2025.04.20
Sorry, but the photos posted in the list are rescaled to a maximum of 1024 pixels? I tried with the last image (1920 pixels) and it was reduced to 1024pixels Il giorno dom 20 apr 2025 alle ore 09:37 Danilo Pivato via groups.io <BigBangObservatory@...> ha scritto:
Hi, I'm attaching the image again with higher resolution
Best,
Danilo
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Re: Comet C/2025 F2 (SWAN) > 2025.04.20
Hi, I'm attaching the image again with higher resolution
Best,
Danilo
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Re: Comet C/2025 F2 (SWAN) > 2025.04.20
And the head looks quite elongated.??
Clear Skies,
Chris Schur
Schur's Web Portal: http://www.schursastrophotography.com
On Saturday, April 19, 2025 at 11:25:35 PM MST, Robert Pickard via groups.io <rpickard1997@...> wrote:
Appears that the comet is in big trouble to me
On Sun, Apr 20, 2025, 12:52?AM Danilo Pivato via <BigBangObservatory= [email protected]> wrote: Attached is a photo of comet C/2025 (SWAN) dated 2025.04.20 captured just over 7° from the horizon
Happy Easter!
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Danilo Pivato
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Re: Comet C/2025 F2 (SWAN) > 2025.04.20
Appears that the comet is in big trouble to me
On Sun, Apr 20, 2025, 12:52?AM Danilo Pivato via <BigBangObservatory= [email protected]> wrote: Attached is a photo of comet C/2025 (SWAN) dated 2025.04.20 captured just over 7° from the horizon
Happy Easter!
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Danilo Pivato
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Comet C/2025 F2 (SWAN) > 2025.04.20
Attached is a photo of comet C/2025 (SWAN) dated 2025.04.20 captured just over 7° from the horizon
Happy Easter!
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Danilo Pivato
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Mike Olason
Erik
Danilo Pivato
