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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.mp4It was indeed. The Beacon was a brilliant venue thanks to Marion and Inverclyde, Involving the choir in a music-themed meeting was inspired, great speakers, lovely weather and a spectacular aurora on the Friday night.
The other highlight for me was seeing PS Waverley steaming off up the Clyde from her berth at Greenock with a loud burst on the horn during Alec Mackinnon’s talk. The attached pic shows the view we had out the windows from the lecture room. I’m a sucker for anything steam powered and she must be one of the most beautiful ships around.
Indeed. Amazing views over the Clyde from up in in Greenock. No camera with me so visual only but a really colourful, bright and dynamic display all over the sky. I can see that it was a really impressive display back home in Essex too. A great start to the BAA Spring meeting weekend!
Mike,
Here’s an example from one of my meteor cameras with R Lyr marked. This is an average of 256 video frames (at 25 fps) using an IMX291LQR based camera with no IR filter. The Bayer matrix on these cameras is designed so that all the pixels have a passband at IR so the chip is effectively a mono sensor in IR. This is one of the problems of trying to use these meteor cameras to monitor variables.
Nick.
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That is absolutely bonkers. So some people have ended up with free Seestars. I hope Amazon end up paying for this rather than the vendors.
It seems that total eclipses induce a kind of temporary madness in a large number of people. It must be something to do with those extra UV rays during he partial phase.
I’ll be attempting to image 12P during totality. At 4th magnitude it should be fairly easy. At the 2020 eclipse I got C/2020 S3 (Erasmus) which was fainter (5th mag) and closer to the eclipsed Sun:
https://britastro.org/cometobs/2020s3/2020s3_20201214_1610_ndj.html
The trick will be to take lots of frames during totality, calibrate them with some very good flats and then stack them.
Seeing the comet visually will be very challenging. The sky will be fairly dark at this eclipse since the shadow is broad but it will probably be the equivalent of the western sky at the end of civil twilight. I’ve seen numbers such as 13 mag per square arcsec quoted. Think how hard it is to see a 4th mag comet in a very light polluted sky (say 16 mag per square arcsec). I’ll certainly be having a quick look with binoculars though!
Indeed Steve, that is total BS written by someone who has clearly never seen a total eclipse so I think “reputable author” is rather kind. The surface brightness of the inner (K) corona is about 1 millionth of the surface brightness of the photosphere so similar to the surface brightness of the Full Moon. There is lots of very bad advice out there about looking at the totally eclipsed Sun. This is particularly awful:
https://jamanetwork.com/journals/jamaophthalmology/fullarticle/2816113
To quote: “It is not safe to view a total eclipse without added eye protection, even during the 90 seconds when an eclipse is total”. If people follow that advice on April 8 they won’t see much!
To be clear, during totality it is perfectly safe to view the eclipse with any optical aid you wish to use and no filters. I have always watched the 2nd contact diamond ring with the naked eye then switched to binoculars/telescope for totality and then gone back to naked eye as soon as the chromosphere appears just ahead of 3rd contact. For photography/video I’ve taken the filter off a minute or so before second contact and put the filter back after third contact. I have never had any sensor damage from doing that (although your experience may be different and I take no responsibility etc. etc.). My video from last April is here:
https://www.youtube.com/watch?v=QmoSTGQ6hpE
and it shows prominences and the inner corona for around a minute before and after totality.
