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Most likely you have a start time set before the launch time. The last line of all those error messages is:
No ephemeris for target “James Webb Space Telescope (spacecraft)” prior to A.D. 2021-DEC-25 12:48:00.0000 UT
Since the launch window opens at about the same solar time every day the chart should remain valid by just offsetting the dates, so, for instance, if it does go up on Christmas day then substitute 27.0 for 26.0 and so on. There will be an eastward drift of 4 mins a day in RA as well. In any case the JPL Horizons ephemeris will be updated to reflect the actual launch time.
It is very well placed for us and everyone but that is not entirely a coincidence. It is going in the anti-solar direction and the launch is scheduled to avoid getting too close to the Moon. Winter is definitely good for us in the northern hemisphere since L2 is currently high in the sky.
There’s not much detail available about what will happen to the cryogenic upper stage following JWST separation which occurs at around 30 minutes after launch. JWST is directly injected into a transfer orbit to L2 so the upper stage will probably be close by but it will probably do some form of deflection burn and JWST itself will do its first course correction at L+12.5h so the two will drift apart. There is another course correction burn scheduled for L+60h. I don’t know how bright the upper stage will be but on the first few nights I would expect it would be detectable and fairly close to the spacecraft. I’ve imaged Centaur upper stages at ranges of more than 700,000 km and the Falcon 9 upper stage at 400,000km but the Ariane upper stage is smaller I think. The Centaurs also do propellant dumps which can be interesting to watch. I assume that the Ariane stage does something similar.
Just for the record your attachment is a doctored version of the Time cover. The original is here. Whatever your views on Elon Musk you should have pointed that out. Twitter is not an ideal primary source for much.
Thanks all for the positive Sky Notes comments. I do appreciate having the opportunity to show some of the excellent work that our members do.
Oddly enough I am seldom referred to as a gentleman…
The JBAA is one of the few journals/periodicals that I continue to get as a physical thing. I’ve been a member of the BAA since 1974 and my run of Journals goes back getting on for 50 years (scary) but still only takes up a couple of metres of shelf space so storage isn’t really an issue. A bit like Jeremy I find that I don’t read digital copy in the same way as physical, its much more a quick scan then store it on the computer to look at another day. I tend to embrace new technology but reading for pleasure is still definitely physical books for me and I feel the same way about the Journal.
As Dominic says, you have access to the electronic Journal now so can try it and see how it works out.
Just search for SOLO on JPL Horizons. We’ll get a good view of it outbound on the evening of Nov 27.
That looks like a very nice setup. I couldn’t find it stated explicitly but I think your 60MP sensor is an IMX455. Combining the wide field of that system with automated plate solving and photometry would make it very powerful. Adding moving object detection and astrometry would be even better.
Are you using ACP for scheduling?
Hi Simon, It’s not an observing session but we do have a meeting coming up in Leeds next April. Hope to see you there.
The formation of dust is the usual reason for these sudden dips, and that is consistent with the reddening as shown in the recent photometry, but what about the big humps when it was bright? Is that dust related too or is it an actual brightening of the disc? V1405 Cas has these humps too whereas other novae (V1674 Her for instance) don’t.
Novae are such fascinating things!
I suspect that this particular flare was caused by DirecTV 7S. It was boosted to the graveyard orbit at the start of 2021 (see here) which is why it is around 370km higher than the other two. It would have been passivated and would not be under control which would explain the odd geometry for this glint.
Here is what one of those GEO flares looks like in real time. The attached is a still from a meteor camera video which you can see here. The video starts at 2021-11-03 01:09:45 UTC and the flare reaches around 2nd mag at 01:09:56 and lasts for around 15s. The potential candidates within 0.1 deg of the estimated position are:
2021-11-03 01:09:56.000000 UTC TOPO 28238 143.17 24.40 0.07 39494.87 -0.009 DIRECTV 7S
2021-11-03 01:09:56.000000 UTC TOPO 38741 143.07 24.34 0.07 39129.06 -0.000 HYLAS 2
2021-11-03 01:09:56.000000 UTC TOPO 47306 143.17 24.36 0.08 39122.74 0.000 TURKSAT 5AThe solar phase angle at the time of this flare was 125 deg so nowhere near opposition.
I don’t know whether there is a website which allows you to search for satellites which are in a particular direction at a given time but I computed these directly using TLEs downloaded from here.
That is a very interesting video. I’ve estimated the time of the brightest one as 2021-10-11 00:26 and its position as azimuth 177, alt 29. If you search within 2 deg of that for Kelling you get this list of satellites (This is a bit of a mess but I can’t attach a text file since it is not one of the permitted file types:
UTC ID Az Alt Ofs Rg (km) RR (km/s)
===========================================================================================================
2021-10-11 00:26:00.000000 UTC TOPO 24748 175.99 28.87 1.16 39039.51 -0.070 DIRECTV 6 (TEMPO 2)
2021-10-11 00:26:00.000000 UTC TOPO 32299 175.37 29.43 1.91 38664.80 -0.000 ASTRA 4A (SIRIUS 4)
2021-10-11 00:26:00.000000 UTC TOPO 33414 175.84 28.30 1.50 39268.93 0.004 VENESAT-1
2021-10-11 00:26:00.000000 UTC TOPO 36831 177.75 29.53 1.01 38670.19 0.000 RASCOM QAF 1R
2021-10-11 00:26:00.000000 UTC TOPO 39773 177.53 29.57 0.84 38665.08 -0.001 EUTE 3BMy guess is that the bright one is Eutelsat 3B. It has large solar panels (around 70 m^2) and could certainly flare to negative magnitudes if the geometry was right.
If you do the calculations it is not that surprising if it is a specular reflection from the solar panels. Around opposition these are pointing straight back at us and they are quite large. A quick order of magnitude calculation follows. Please check!
The sun has an apparent area of around 1E-4 rad^2. A 1m^2 mirror at 40,000 km is around 1E-15 rad^2. Assuming the mirror is a perfect reflector it will have the same surface brightness as the sun so will be 2.5 log10(1E-11) fainter so around 28 mags. The sun is mag -27 so the 1m^2 mirror in GEO could be around mag 1. GEO satellites have solar arrays of 50m^2 or more so a bright NE glint is certainly possible.
A lot of that is down to the IoP’s AV technician who did a fantastic job supporting us before and during the meeting.
Livestream is here: https://www.youtube.com/watch?v=pYFNWAlu6uw
