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It looks as if comet 12P/Pons-Brooks is in outburst again. I imaged it early last night from Chelmsford (Nov 14.75) and the magnitude rose from 13.6 to 12.5 in 25 minutes. My last image, on Nov 13.80 using the Alnitak Observatory telescope in Spain, shows it as 14.7.
If you have any images of 12P taken on Nov 14/15 could you please let me know so that we can build a comprehensive light curve of this event.
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I’ve just imaged the comet again and it was mag 9.4 on Nov 15.72 in a 34 arcsec aperture. This is a really big outburst and the comet should be a fairly easy visual target in a moderate telescope at the moment.
Yes indeed! I’m seeing a five magnitude increase in just 24 hours. The comet was mag 10.0 at Nov 14.85. See my image here https://britastro.org/observations/observation.php?id=20231115_182423_a28e0b17670bfdcf
I made it magnitude 9.3 this evening! It was quite unmistakable at x38, even though the sky wasn’t completely dark at 1730UT.
For the record, 20231113 18:13*, using Gaia g magnitudes derived from stars in the FOV and applying an aperture that was just 6x 1.55″ pixels across, I get a brightness of about 14.7 with an estimated error of 0.15 (not sure why its a big as that).
*20231113.759
It’s looking remarkably like 17/P Holmes tonight with a beautiful blue/green coma surrounding the nuclear region.
Am imaging it now at 1830h.It’s cloudy here tonight but I’m getting some images from the Alnitak telescope in Spain. This outburst is different to the others and David is right that this does look like a mini 17P/Holmes. I’m assuming the faint larger disk is the gas coma which expands quickly and the bright inner disk is the slower moving dust but don’t quote me on that.
It would be an interesting object to try spectroscopy on while it is currently bright…
Its now clouded over but was really surprised to see just how bright it has got! Images posted in gallery.
My latest image (and an image by Peter Carson at around the same time) does show some emerging detail in the bright inner coma:
https://britastro.org/observations/observation.php?id=20231116_205120_39e0a2e36927510e
The attached image is around 2 arcmin square, N up. The bright inner coma is now about an arcmin in diameter.
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Hi all,
I managed to image 12P last night from Spain. Here is a stack of 20 x 60 secs with an L filter. North is to the left. Image is 18′ x 14′ (0.48 “/pix).
The nucleus is very bright!.
Cheers
Ian.Attachments:
Front page news on today’s Spaceweather.com!
https://www.spaceweather.com/archive.php?view=1&day=17&month=11&year=2023
The inner bright coma is showing quite a bit more detail now. The attached is 4 arcmin square, N up, E left, taken using the Alnitak telescope in Spain at 1906 UTC on Nov 17. There appear to be two blobs of material north of the coma. Does anyone else have any images that can confirm this?
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Hi,
Also got some new images from Spain around 18:52 UT.
I dont think I can confirm the two blobs.
Interesting to see new dark streak in the dust sphere.
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Lars Zielke
I also got another image last night. I captured the dark streak nicely, but my processing does not seem to have shown the blobs.
Cheers
Ian.Attachments:
Hi All,
This comet is predicted to occult the 12.5 magnitude star UCAC4 643-061621 on Monday 04th Dec 2023 at 22:29 GMT. Maximum predicted duration is 0.7s. The star will be low in the NW at that time (12 degrees) and the shadow path runs roughly N-S through England and Scotland.
Whether or not a dip in the brightness of the star will be detectable will of course depend on how bright the comet is at the time. This may however be a useful opportunity to gain a light profile of the coma.
My observatory is right on the edge of the predicted shadow path and I’ll need to do some trials to establish if local obstructions will prevent me making this observations – I may need to dust off the mobile system!Details of this stellar occultation are available here: https://cloud.occultwatcher.net/event/1067-12P-262541-650415-U061621
Let’s hope the weather cooperates.
Best regards
William
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I’ve reprocessed my images from last night and the two faint blobs were artefacts caused by some problems on three of the subframes. I’ve removed these from the stack. Updated image attached showing the prominent features to the east of the centre.
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And here’s tonight’s. The photocentre is still strong. No sign of any fragmentation but you wouldn’t expect any since this comet has gone through perihelion many times and has a large nucleus. Maybe some big chunks coming off but nothing more than that.
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Here is a plot of the magnitude of 12P in an approximately 9 arcsec radius photometric aperture. These are all unfiltered vs Gaia G.
While the total magnitude of the comet is constant this is within an expanding aperture, when you restrict the aperture to the region near the nucleus it gives some idea of the amount of dust in that region. The initial rise is incredibly steep. I caught it just after the outburst on Nov 14.75 and it brightened by 1.2 magnitudes in 20 minutes eventually reaching something like mag 9.3. It was 14.2 in this same aperture before the outburst so that is a rise of a factor of 100 in a few hours. That is a lot of dust coming off the nucleus in a very short time.
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