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All the videos are now available here. Apologies again for the poor sound quality.
Yes, very variable brightness and separation. I’ve posted a frame from my video here. I’ll put the full video up shortly.
Had a video running for this evening’s 2130 UTC pass. The sky was bright and cloudy but I recorded 14 of the Starlink spacecraft. I was using a Sony A7s with an 85mm lens at f/1.4, 1/25s, ISO20000 pointed just left of Spica. The first one came along at the time predicted but the rest were strung out over around 3.5 mins. Limiting mag of the video was around 7.5. The spacecraft were all around mag 5.5.
I’m suprised by that. I use winsorized sigma clipping with dithering for all my stacks since I have planes, helicopters etc. to deal with in addition to satellites and dark frames are never perfect. I’ve never noticed any degradation in the photometric accuracy of my stacks using sigma clip compared to a simple mean. In fact I would have thought that it would be better since you are removing residual hot pixel outliers. As Grant says, it would be interesting to see a reference that discusses this.
Not good from our latitudes in the summer but another reason for imagers to use short subs and sigma clip stacking I guess. Not sure of the effect on surveys like LSST. It will be imaging only after the end of astro twilight and it is at latitude 30S so twilight will be much shorter. I guess someone could calculate the period of time during astro night when 500km high LEOs are illuminated from that site.
Calsky has an amateur generated TLE for the train and will do predictions. Use Spacecom ID 99201. The TLEs are currently over a day old and the orbits will be evolving quite rapidly as each spacecraft uses its ion thruster to move to its operational configuration. The prospect of 12,000 of these things in LEO is indeed a concern for astronomers although there will be long periods when they are not illuminated.
It was cloudy in Essex last night but John Mason had clear skies for the low pass at 22:16 UTC and didn’t see anything.
Epoch is 24. May 2019 Starlink Trail1 99201U 19894A 19144.95562291 .00000000 00000-0 50000-4 0 022 99201 53.0084 171.3414 0001000 0.0000 72.1720 15.40507866 06I’m pleased to say that video and audio from all of the talks on Saturday appear to have recorded correctly. I should be able to post the videos in the next week or so.
If you are coming to the meeting on Saturday by car please see the directions attached. There is limited parking in the school carpark near the venue. Alternatively there is paid parking in Nunnery Lane. York has a number of Park and Rides which may also be an option.
Hoping to see you there.
That’s a really interesting report. Prentice and Alcock would be amazed at so many high quality meteoroid orbits in such a short time.
I get 14.11 G tonight using a 90mm refractor from Chelmsford and the green pixels from an RGB detector. There are lots of galaxies in the field although the conditions here are very hazy.
I very much doubt if you could detect any natural scattered sunlight in the sky after the end of astro twilight from anywhere in southern England. I’m not sure how stable the SQM photometer is but I imagine you are detecting man-made scattered light. You would need to have a very good sky for natural sources such as airglow to have a detectable effect.
I attach a plot from “Sunsets, twilights and evening skies” by Aden and Meinel. This is a lovely book and has several chapters on twilight. Also, a plot from an imaging session on La Palma where the skies are really dark and, in this case, very transparent . This shows the median sky background for several imaging sessions of objects at different altitudes. Astro twilight begins at 04:52 and it is only just detectable even from a place with very dark skies.
It’s all a bit academic for me in Chelmsford. On very good nights I can only just detect the sun in my skies when it is between 15-16 deg below the horizon!
This is an interesting read.
There is also a bright nova in M31 at the moment discovered by Hornoch and Zhang. It was fainter than mag 18 at discovery but I measured AT2019bsd as 15.1 unfiltered (ref UCAC-4 R) last night. It is sitting on TNS with no spectral confirmation.
Have fun with the images. That software routine would be very useful when polar aligning. I did this for my mount by imaging the pole undriven and then imaging the pole while slewing in RA. I needed to find the centre of the arcs and ended up printing the images and using a compass so something that did this automatically would be very helpful!
If anyone wants to have a play I attach a couple of undriven images of the pole. One was taken when I was polar aligning my mount in Jan 2018, the other was taken tonight. They are both 600s exposures with the same camera/telescope and the FoV is 36×24 arcmin. The original FITS files are here.
