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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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I’d forgotten about this. I’ve just had a look and Pallas has just sneaked in to my 30s patrol image from last night.
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As you say, the first opportunity to get this object from the UK is as it gets dark on June 29, around 8 hrs after close approach. It is then moving rapidly north through Pegasus. It is then visible throughout the short night moving rapidly but quite bright (fading from 11.3 to 11.7). By the following night it is well-placed in Andromeda and moving much more slowly but it will have faded to below 14. It then stays in Andromeda as it moves away from us and fades to around mag 18 by the night of July 5/6.
I had a go at imaging Capella this afternoon in a clear, transparent sky after I’d finished with the Sun. I took 1000 frames with an exposure 879 us and gain set to minimum on an ASI1600 using a 90mm, f/6 refr and then took the same number of dark frames with the same exposure. Capella was quite close to the Sun so there is a lot of forward scatter from drifting pollen but, after calibration, and taking the V mag of Capella as 0.08 I get a sky brightness of 2.6 mag/arcsec^2. Remarkably close to what I expected. A video of the calibrated light frames is here:
The Meinel plot approximates the response of the human eye which is what I think Grant was interested in. Clearly things would be different if you used filters etc.
What’s a summer blue daytime sky?
Anyway, interesting calculation. The wonderful book “Sunsets, twilights and evening skies” by Aden and Marjorie Meinel contains the attached plot. It indicates a factor of 70 million between a perfect night sky and the noon zenith sky. That is 2.5 * log10(70E6) = 19.6 mags. Assuming a perfect night sky to be 22 mags per square arcsec that would put the noon daytime sky at about 2.4 mags per square arcsec so a bit brighter than you calculated.
The surface brightness of the Full Moon is around 3.4 mags per arcsec so that would imply that it is about 40% the surface brightness of the daytime sky which would be easily detectable with the naked eye. That is something you should be able to demonstrate easily by taking an image and measuring it.
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A response to this question posted on comets-ml pointed to a Cloudy Nights discussion from last month which had a plausible explanation which was that the orbit of 13P was better known than 12P so it was very quickly recognised as a recovery when Brooks found it on the return.
https://groups.io/g/comets-ml/message/32292
https://www.cloudynights.com/topic/920186-the-name-of-the-comet-13polbers-problem/#entry13436144Well, if we take Ireland as being 500 km long and the nearest Mars comes to the Earth as 60 million km then the flag would subtend around 500/60E6 = 8 microradians or about 2 arcsec so a Martian Damian Peach would definitely be able to resolve it.
Blimey. All that advice and only a day to get your telephotographic gubbins together and haul it up onto the roof of Selfridges along with a friend to help you get the focus right. Am I correct that he is recommending focussing without a filter as long as the “magnification is very high”? Also looking directly at the Sun through the finder tube to line the camera up. Health and Safety clearly wasn’t much of a thing in 1912. I doubt if they had high railings around the roof either.
I was up in Greenock but my meteor cameras in Chelmsford recorded the aurora.
One hour timelapse from NW colour camera: https://nickdjames.com/aurora/20240510/auroraNW_20240510_2300_ndj.mp4
Full night timelapse from N mono camera: https://nickdjames.com/aurora/20240510/UK004D_20240510_201747.mp4
Full night timelapse from NW mono camera: https://nickdjames.com/aurora/20240510/UK004G_20240510_201839.mp4
Full night timelapse from SE mono camera: https://nickdjames.com/aurora/20240510/UK004E_20240510_201811.mp4
Full night timelapse from SW mono camera: https://nickdjames.com/aurora/20240510/UK004F_20240510_201825.mp4
Full night timelapse from zenith mono camera: https://nickdjames.com/aurora/20240510/UK004H_20240510_201845.mp4
