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Torrential rain this evening for me on La Palma so I have spent some time putting together this mosaic of the comet based on images from my ASI2600MC + RedCat 51 taken last night (Oct 14). Each panel is approx. 5×4 deg and the total image is 17.3 x 4.2 kpix:
https://nickdjames.com/Comets/2024/2023a3_20231014_ndj.jpg
If you zoom in you will find Comet 13P/Olbers about midway along the bottom of the image, also the globular M5 and quite a few galaxies. 13P looks very puny compared to C/2023 A3.
Thanks to everyone who managed to observe the comet last night. There are some great images here and in the gallery. It looks like there was a lucky break in the weather over NW Europe. The comet will now be moving into darker skies and the tail will be getting longer in the evening sky over the next few days so definitely worth making the effort.
I’m very envious. I’m on La Palma at the moment and it was raining at the top of the mountain yesterday evening. The forecast isn’t brilliant for tonight either!
So that does look very interesting. A normal spectroheliograph has an oscillating slit. Is my understanding correct that this relies on the Sun drifting across the slit to form an image? Looking at the tripod it is clearly not driven. If so, it must use some clever sensor integration trick.
Yes, the tail geometry changes very quickly over the next few days. The most recent animation from STEREO shows how quickly the tail is swinging around from its viewpoint.
This is the latest STEREO HI image from 2328 on October 7. The tail structure from the viewpoint of STEREO is now very complex.
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And from October 6 at 2338 UTC. Lots of detail visible in that broad tail. STEREO-A is currently 26 deg ahead of us along the ecliptic so it is seeing the comet from a different point of view. Tomorrow (Oct 9) is the date of conjunction. The comet will then pull away from the Sun into the evening sky.
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Here’s the latest uncompressed FITS from the STEREO HI. This is from Oct 5th at 23:28. Lots of nice tail detail visible.
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60s exposure in grotty, hazy conditions from Chelmsford tonight (Oct 4) shows it around mag 13.2 unfiltered vs Gaia G.
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It is continuing to fade. For photometry it is worth checking that you don’t include the 15th mag star just west. There are also a few 17th and 18th mag stars within a few arcsec that will come into play as it fades. Attached image taken earlier this evening as it got dark.
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Last night (July 14/15) was clear here in Chelmsford. This asteroid is now 12 million km away and is around 19.3 at its brightest. It varied quite a bit over my 20x60s subs and, at its faintest is probably mag 20 or so.
https://britastro.org/observations/observation.php?id=20240715_211942_4a7a99b2a55cc815
Giovanni – The Nikon D3000 shouldn’t do anything with the pixel data in raw mode so none of the setting that change JPEGs should do anything. I think the CMOS sensor in the D3000 is 12-bit native. Could you put some of your raw images online somewhere so that I can download them and have a look?
Dave Coffin’s dcraw is the basis of most, non-proprietary, raw converters out there:
https://en.wikipedia.org/wiki/Dcraw
It is open source and converts from pretty much any raw format to start TIFFs. It can do this without applying any modification to the data. I believe that there are Windows versions out there.
A nice application which uses dcraw is rawtran. This converts raw files to pseudo photometric band FITS files:
2024 MK was still a fairly easy target this morning (July 7) at a range of 6 million km. Magnitude was around 18.6 at brightest.
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The Goldstone SSR did some bistatic Doppler radar imaging of 2024 MK using DSS-14 (transmit) and DSS-13 (receive) at around 2m resolution. The images show that the asteroid is around 150m across:
https://echo.jpl.nasa.gov/asteroids/june2024.goldstone.planning.html
Petr Pravec had already determined that it was a non-principle axis (aka tumbling) rotator from optical observations showing multiple rotation periods from just over an hour down to around 20 minutes.
That looks very impressive!
This article on the silvering of the 100-inch Hooker mirror is on a slightly bigger scale:
https://articles.adsabs.harvard.edu//full/1933ASPL….2….5E/0000005.000.html
It’s clear in Chelmsford at the moment. Here is the asteroid.
https://britastro.org/observations/observation.php?id=20240629_223859_f40c4f01458212ac
This is pretty old news. Here is some background: https://www.iau.org/static/science/scientific_bodies/commissions/c3/c3-annual-report-2022-2023.pdf
A key comment is that “The OC is worried that a new nomenclature might be simply ignored by most astronomers”. Indeed it might.
The early explorers were clearly not “nice” people as currently defined but who of us today will pass muster when compared to the moral standards of people 500 years in the future?
And here’s a colour wide-field image from tonight (Jun 24/25). The bright star at the top is epsilon CrB which is mag 4.2. T CrB should be brighter than this when it goes off.
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