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| C/2025 F2 (SWAN) = SWAN25F https://forum.vdsastro.de/viewtopic.php?t=7624 |
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| Autor: | Mike Olason [ 16. April 2025, 00:57:29 AM ] | ||
| Betreff des Beitrags: | Re: C/2025 F2 (SWAN) = SWAN25F | ||
The Moon was 94% illuminated on the morning of 2025 April 15 UT, Comet C/2025 F2 was magnitude G=9.4 as calculated from 6x20 second images thru a green filter in an aperture diameter of 3.5'. The coma was 3' wide, the wavy tail in the image FOV was 53' long at a position angle of 309 degrees from the coma.
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| Autor: | Mike Olason [ 16. April 2025, 14:41:53 PM ] |
| Betreff des Beitrags: | Re: C/2025 F2 (SWAN) = SWAN25F |
The comet did not look good in 20 second images this morning. Unlike yesterday morning when the tail was easy to see in 20 second images there is no tail visible this morning in 20 second images and the coma does not seem to have a nice bright center. It could be the Moon, but just like yesterday morning the Moon is far to the southwest. The skies were clear, at least until the nice aroma of a skunk made its presence just as the skies brightened. Not suggesting anything, but the comet sure did not look like yesterday. After some sleep will put together some images and measure the magnitude. With the comet being so low maybe there was something in the atmosphere that was not apparent and dimmed everything. |
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| Autor: | Mike Olason [ 17. April 2025, 01:45:13 AM ] | ||
| Betreff des Beitrags: | Re: C/2025 F2 (SWAN) = SWAN25F | ||
Using the same equipment and setup as yesterday morning, my stuff could not see any sign of the long tail observed yesterday morning although I am sure that it must be there, just a lot fainter. On the morning of 2025 April 16 C/2025 F2 had faded some from yesterday morning with a magnitude G=9.6 as calculated from 6x20s images thru a green filter in an aperture diameter of 3.5'. I don't think the Moon made any difference since it was about the same illumination as yesterday morning and in the southwest sky. Both mornings the sky appeared perfectly clear but maybe there was something I could not see in the sky this morning near the horizon to obscure the tail.
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| Autor: | Michael Jäger [ 17. April 2025, 06:17:29 AM ] | ||
| Betreff des Beitrags: | Re: C/2025 F2 (SWAN) = SWAN25F | ||
Es geht offenbar dem Ende zu. 16.4. Bild vom 16.4. 2.40 UT
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| Autor: | Norbert Mrozek [ 17. April 2025, 12:44:51 PM ] |
| Betreff des Beitrags: | Re: C/2025 F2 (SWAN) = SWAN25F |
Dateianhang: swan-lrgb-15-4-25_40bilder2_7.jpg [ 332.72 KiB | 23799 mal betrachtet ] Dateianhang: swan-lrgb-15-4-25_40bilder2_6.jpg [ 265.51 KiB | 23799 mal betrachtet ] 8" / 3.0 Newton, Touptek 2600 MM. Gruß Norbert |
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| Autor: | Mike Olason [ 18. April 2025, 00:39:14 AM ] | ||
| Betreff des Beitrags: | Re: C/2025 F2 (SWAN) = SWAN25F | ||
Norbert, very nice images, hopefully you will get to observe a lot more gas from C/2025 F2, but one does start to wonder. On the morning of 2025 April 17 UT the only tail visible in the small 50mm f/5 refractor was a short fan tail above the coma in these images. The comet was magnitude G=9.6 as calculated from 5x20 second images thru a green filter in an aperture diameter of 3.5'. If the comet has now settled into its normal magnitude curve (the comet has been around magnitude 9-9.5 for the past 9 mornings) after some major eruptions when first discovered, what does that say about its peak brightness at perihelion which is only 2 weeks from now?
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| Autor: | Norbert Mrozek [ 18. April 2025, 15:11:26 PM ] |
| Betreff des Beitrags: | Re: C/2025 F2 (SWAN) = SWAN25F |
Thanks Mike, your pictures show the comet's evolution very well. It looks rather negative. |
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| Autor: | Mike Olason [ 19. April 2025, 04:27:23 AM ] | |||
| Betreff des Beitrags: | Re: C/2025 F2 (SWAN) = SWAN25F | |||
Comet C/2025 F2 (SWAN) continues to fade slowly, on the morning of 2025 April 18 UT the comet was magnitude G=9.8 as calculated from 5x20 second images thru a green filter in an aperture diameter of 3'. The comet coma was 2.5' wide and the comet had a fan tail 2' long at a position angle of 309 degrees from the comet coma. There is a lot of speculation about the comet disintegrating, so put together some 4.3'x4.6' FOV images of the comet to maybe help with that conversation, although using a small scope at low altitude with a 75% illuminated Moon is not ideal to see much fragmentation. Unfortunately, showers tonight so probably no images in the morning.
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| Autor: | Mike Olason [ 20. April 2025, 15:23:59 PM ] | ||
| Betreff des Beitrags: | Re: C/2025 F2 (SWAN) = SWAN25F | ||
On a nice clear morning of 2025 April 20 UT, C/2025 F2 was magnitude G=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.
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| Autor: | Mike Olason [ 21. April 2025, 02:28:34 AM ] | ||
| Betreff des Beitrags: | Re: C/2025 F2 (SWAN) = SWAN25F | ||
C/2025 F2 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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| Autor: | Mike Olason [ 21. April 2025, 15:43:25 PM ] | ||
| Betreff des Beitrags: | Re: C/2025 F2 (SWAN) = SWAN25F | ||
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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| Autor: | Mike Olason [ 22. April 2025, 17:02:53 PM ] | ||
| Betreff des Beitrags: | Re: C/2025 F2 (SWAN) = SWAN25F | ||
On the morning of 2025 April 22UT C/2025 F2 had brightened a little to magnitude G=9.3/G=9.6 as calculated from a couple different sets of data in an aperture diameter of 3'. What is interesting is that there appears to be clumps or fragments in the images from these calculations which may account for the comet brightening. These images were collected at an altitude of 5 degrees under nice clear morning skies just as twilight was approaching.
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| Autor: | Martin Nischang [ 27. April 2025, 19:14:02 PM ] | ||
| Betreff des Beitrags: | Re: C/2025 F2 (SWAN) = SWAN25F | ||
Hi Mike, kudos for catching this fading comet  I was able to image it on the morning of 20th of April as well, and hoped to get a more elongated tail appearance in this stack of 25 images of 60s each. The exposures had Mirach centered, but the croped image, as a preview, shows that maybe I was not successful in getting more out of it, or there was simply no more activity this morning. But, the tail is still there, as I heared... we will soon get to know it.
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| Autor: | Mike Olason [ 28. April 2025, 11:52:37 AM ] | ||
| Betreff des Beitrags: | Re: C/2025 F2 (SWAN) = SWAN25F | ||
Martin, that is a very nice color image of the comet considering the low altitude. C/2025 F2 (SWAN) has been a bit of a challenge in the evening twilight skies from Tucson. The wind has been trying to blow my house down the past several days and this results in lots of dust in the air, trying to find an area of shrubs to shelter the telescope from the wind has been a challenge since I can't see the comet from my home. Then, of course, the comet is setting over the light pollution dome of Pheonix in twilight skies. The low altitude of 2 to 3 degrees when the skies finally get dim enough to try to find a magnitude 9-10 comet does not help. After a few evenings of seeing nothing, this evening 2025 April 28UT showed a very faint white area where the comet should be located, but it is so faint that it is hard to show in images and if one did not know where the comet should be located it certainly would not draw one's attention to that area. Hopefully if the sky conditions improve the comet will become more obvious.
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| Autor: | Thomas Lehmann [ 29. April 2025, 12:48:03 PM ] | |||
| Betreff des Beitrags: | Re: C/2025 F2 (SWAN) = SWAN25F | |||
Vor zwei Abenden hatte ich hier in Weimar einen ausgezeichnet klaren Himmel. Ungewöhnlich gut für meinen Standort inmitten der Stadt. Von der Schulsternwarte auf dem Dach des Friedrich-Schiller-Gymnasiums habe ich zum großen Teil freie Horizontsicht und so habe ich versucht, die Reste des Kometen bei 5.5° Höhe abzulichten. Aus 12 Minuten Belichtungszeit ist die unten stehende Aufnahme entstanden. Der Kopf des Kometen ist in einer 3' Apertur noch 9.8mag hell (im grünen Farbkanal). In der stärker geglätteten Negativvariante des weitgehend von Sternspuren bereinigten Kometenstacks ist der Schweif bis etwa 20' Länge zu erahnen. Ich hänge mal auch einen Plot der differentiellen Extinktion an, wie er automatisch von meiner AIRTOOLS Software an Sternen in der Nähe des Kometen gemessen und berücksichtigt wird. Kommt ja nicht so häufig vor, dass man bei >10 Luftmassen Fotometrie betreibt. CS Thomas
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| Autor: | Steffen Fritsche [ 29. April 2025, 17:02:03 PM ] |
| Betreff des Beitrags: | Re: C/2025 F2 (SWAN) = SWAN25F |
Lieber Thomas, tolle Leistung bei der niedrigen Höhe. Auch für mich steht der Komet und das Wetter gerade günstig. Ich denke, ich habe ihn auch abgebildet. Die Auswertung hängt aber bei mir. Aktuell werte ich die Nacht vom 3./4.4.2025 aus... Viele Grüße Steffen |
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| Autor: | Martin Nischang [ 30. April 2025, 12:44:06 PM ] |
| Betreff des Beitrags: | Re: C/2025 F2 (SWAN) = SWAN25F |
Hallo zusammen, bei uns gab es ähnlich perfekte Bedingungen wie bei Thomas; am 26.04. mit knapp 21,6 mag/arcsec² (SQM-L) gar einen so dunklen Himmel wie im März/April 2020 (Corona...). Das haben wir unterschätzt. Aber am 27. (Sonntagabend), und auch am gestrigen 29.04. konnte ich die Schweifreste des Kometen noch in Einzelaufnahmen erkennen. Die Auswertung wird noch etwas dauern... zum Glück ist morgen ein Feiertag, aber auch Gartenarbeit muss erledigt werden 
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| Autor: | Robin Hegenbarth [ 30. April 2025, 20:19:11 PM ] |
| Betreff des Beitrags: | Re: C/2025 F2 (SWAN) = SWAN25F |
Hallo zusammen, ist es jemandem von euch zuletzt nochmal visuell gelungen? Bei mir sind jetzt jeden Abend Quellwolken, keine Chance auf klaren Himmel nah am Horizont. Clear skies Robin |
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| Autor: | Robin Hegenbarth [ 01. Mai 2025, 23:09:37 PM ] |
| Betreff des Beitrags: | Re: C/2025 F2 (SWAN) = SWAN25F |
Hallo zusammen, heute Abend hatte ich klaren Himmel bis auf horizontnahe Schleierwolken über Frankreich, die mich nicht gestört hatten. Daher habe ich versucht, C/2025 F2 (SWAN) zu beobachten, es ist mir aber nicht gelungen. Unterwegs war ich mit meinem 12" Dobson mit 49x Vergrößerung ohne Filter und mit meinem 8x56 Feldstecher, den ich nur zum Aufsuchen der Plejaden benutzte. Der Komet hätte sich 3° rechts der Plejaden befinden sollen. Zunächst beobachtete ich um 21:35 MESZ die Plejaden 8° über dem theoretischen Horizont mit meinem Feldstecher. Die Plejaden konnte ich dann im Teleskop schnell finden und um 21:50 MESZ war ich im Zielgebiet, in dem sich der Komet befinden sollte, etwa 7.5° über dem theoretischen Horizont. Eine markante kleine Kette von drei etwa 8-9 mag Sternen diente als Referenz-Gegend, von der aus ich immer wieder zur erwarteten Position des Kometen schwenkte. Insgesamt konnte ich nur 8 Sterne bis etwa 9.5 mag im Gesichtsfeld erkennen, das durch die Dämmerung ziemlich aufgehellt war (nautische Dämmerung um 21:58 MESZ). Wegen der wenigen Sterne war es schwierig, mit den Augen den Fokus zu behalten. Den Kometen konnte ich nicht erkennen. Um 22:17 MESZ war das Zielgebiet 4° über dem theoretischen Horizont und ziemlich dunstig. Dann packte ich zusammen. Das Ergebnis der "Beobachtung" dürfte sein, dass da kein Komet bis etwa 8 mag war. Die letzten Schätzungen der Komahelligkeit von euch lagen ja bei etwa 9.8 mag. Das hat mir dann nicht für eine visuelle Beobachtung gereicht. Hatte jemand von euch mehr Erfolg? @Christian, hast Du es nochmal mit 21" versucht? Clear skies Robin |
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| Autor: | Mike Olason [ 02. Mai 2025, 14:01:44 PM ] | |||
| Betreff des Beitrags: | Re: C/2025 F2 (SWAN) = SWAN25F | |||
After a few nights of clouds exactly where the comet was located it was clear on the evening of 2025 May 2. On the evening of 2025 April 29 C/2025 F2 had a 9' long tail at a position angle of 349 degrees, but on the evening of 2025 May 2 the tail was not evident beyond the disintegrated debris field in the 4.8' aperture diameter circle. Using the 4.8' aperture diameter circle to encompass the major part of the disintegrated debris field the comet magnitude was G=8.5 on April 29 and G=8.6 on May 2. There were no stars brighter than magnitude 15 in either 4.8' aperture diameter circle and the faintest stars in all images were about magnitude 14.
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| Autor: | Uwe Pilz [ 19. Mai 2025, 07:16:14 AM ] |
| Betreff des Beitrags: | Re: C/2025 F2 (SWAN) = SWAN25F |
Thank you Mike for your results. At the mailing list, Michael Mattiazzo shows a similar photograph, taken May 16th. The remnant is still there. |
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| Autor: | Mike Olason [ 23. Mai 2025, 00:54:12 AM ] | ||
| Betreff des Beitrags: | Re: C/2025 F2 (SWAN) = SWAN25F | ||
Hello Uwe, I did see Michael's May 16 image. After the images collected on May 2 UT above, it was cloudy from May 3-6 UT. On May 7 UT the skies were clear, but it was very windy, dusty, the comet was at 4 degrees when enough stars were visible in the orange twilight to finally try and auto track for image collection. The wind and resulting bad auto tracking messed up a lot of images. The comet remnants were not visible in any of the images or any combination of the images, the circled areas are where the comet remnants were expected to be visible. It was cloudy again on May 8. May 9 was clear, but the comet was below 2 degrees in orange twilight and short untracked images did not show any comet remnants. It was disappointing, May and June are the driest times of the year in Tucson, usually no clouds. 
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