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Yes, checking that your train actually exists is always good advice at the moment! Hopefully the work to rule won’t have a major impact.
We have over 90 people registered so it should be a good day. We’ll probably end up in the Trafalgar after the meeting although it will probably be more rammed than usual even for a Saturday night in Greenwich. The Kaiser Chiefs are playing at the Naval College at 8:30pm. No doubt “I predict a riot” will be in the set but hopefully there won’t actually be one.
Launch on Falcon 9 looked to be perfect and acquisition of signal happened on time at the New Norcia ground station in Australia. As I write this the spacecraft is being tracked and commanded by the 35-m antenna at Cebreros, just outside of Madrid. I haven’t managed to find an ephemeris but it must be pretty close to the Moon in the sky since the shadow of the subreflector (equivalent to the Cassegrain secondary) is almost on top of the beam waveguide entrance aperture (the hole in the main dish). A live image of the antenna is here:
https://tethys.ejr-quartz.com/cebreros/cebreros.jpg
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At perihelion the Earth’s umbra extends around 1.4 million km away so, as Dominic says, you would only see an annular eclipse from L2 which is around 1.5 km outward from the Sun. Eclipses are really bad things for spacecraft which rely on solar arrays for power so the outbound trajectory will avoids the Earth’s shadow wherever possible. L2 is gravitationally unstable and so spacecraft don’t actually sit at the Lagrange point itself but orbit in a halo around it with relatively frequent small thruster burns to keep them on station. We’ll have another opportunity to watch a spacecraft heading out to L2 when ESA’s Euclid gets launched on a Falcon 9 at the start of July.
Back on topic though. Could those additional items be added to the forum topics list?
Robin. Thanks for that. A very interesting paper.
The Sony IMX455 is certainly a very nice sensor for astronomy. Here’s what you can do with it if you couple it to a Celestron RASA 11 and have very dark skies:
https://www.spaceobs.com/Blog-de-Alain-Maury/MAP-historique-et-description
Nick.
Robin – That was a very interesting programme. Some of the BBC’s science output is still pretty good. Here’s my lightcurve so far taken from the BAA database. Hopefully this good weather will continue so we can keep monitoring it.
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It’s now (2023-05-21 22h UT) around 11.3 so still brightening quickly. The total integrated magnitude of M101 is around 8.0 so this one object is currently 5% of the brightness of the entire galaxy.
That’s interesting. The latest non-detection on TNS is from ATLAS at 2023-05-18 10:17 UT when they reported > 20.5.
I imaged it earlier this evening (May 20/21) and it has risen to around mag 12.0 now.
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It’s rather hazy in Chelmsford but here but here is an unfiltered image of the SN.
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Yes, it is surprisingly bright. I assume that it is because of the very large solar arrays and a good solar aspect angle. The RIME antenna is now deployed too after a bit of a struggle with the mechanism.
Yes, I was a bit disappointed on my last visit to the NHM although I did get to see Winchcombe which made up for the impression that there were fewer meteorites on display there than when I was a lad. While in Western Australia recently I visited the WA museum in Perth. They had a lot of meteorites there including a big chunk of the 22t Mundrabilla meteorite sitting in the weather outside by the bike racks. It would have taken some shifting if anyone had wanted to steal it.
There is a confirmed report on MPML that JUICE flared up to around mag 18 last night (May 9) despite the distance being around 5.6 million km. I don’t know how long this will last but it would be worth a try tonight if you have a chance. It is currently at a declination of -4 deg and an hour or so past the meridian. It is currently cloudy in Chelmsford.
The spacecraft still has not successfully deployed the big RIME subsurface radar antenna. The latest news (not much really) is here: https://twitter.com/esaoperations/status/1655933988991795203.
I was monitoring it in Chelmsford using an HD11 + ASI6200. Half the telescope aperture was occulted by my observatory shed and the the rest was looking through the branches of a tree. Because of this I had to use 0.25s exposure to get the star. At least the sky was clear but but no occultation detected here.
The comet is currently in a faint state. The attached is a 60s exposure taken at 2127 showing the comet and the star.
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Grant – You really do seem to have an extraordinarily unreliable system. If it was me I would have taken a sledgehammer to it by now.
Nick – Well done getting it. It was reported as mag 13 on the first night so in line with my original predictions. You might want to have a go for the Ariane upper stage too. You can get ephems from https://projectpluto.com/sat_eph.htm.
Grant – Good luck with imaging JUICE tonight. A typically excellent Ariane 5 launch. Acquisition of Signal at the ESA Deep Space Antenna at New Norcia was a bit of a nail-biter but in the end everything was fine. It just took a while for JUICE to settle itself down and enable its transmitter.
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Mark,
Thanks for writing that up. It is good to see different approaches.
You are using an elliptical aperture which I don’t think is correct and probably explains the slightly brighter magnitude that you are getting since you will have included some of the dust tail. Comphot always uses a circular aperture which is reasonable since the comet’s coma is likely to be spherical and the rules are that you should not include the tail in the estimate. Also, how do you exclude stars that appear in the aperture? The sigma-clipped comet stack does significantly attenuate stars but they are not completely removed.
You make the comment that you would not normally use this approach with ASTAP. How would you normally deal with the fact that the comet is moving relative to the background since stacking over long periods is often necessary to get sufficient SNR in the outer coma?
Nick.
PS for Grant – Surely your home-brew camera software can query the mount’s commanded pointing position from SkyX and then insert the required FITS keywords. Blind solving is great but it is relatively slow so it is always best to have this data in the header. In particular Astrometrica is a bit of a pain to use if this is not there.
