Forum Replies Created
-
Posts
-
It’s in outburst: https://twitter.com/SuperASASSN/status/889934384496640000
Looks a really interesting bit of kit. A kind of hybrid of visual observing and electronic. I expect it would appeal to a lot of people.
Wow, is it really 28 years ago! Yes, I remember the Titan/28 Sgr occultation very well, particularly the astonishing central brightening when light from the star was refracted around the limb of Titan by its atmosphere. I didn’t have any sophisticated equipment then and the attached photo was taken with a camera mounted on the back of a small refractor.
Cassini is a mission very close to my heart. I was there for the launch and will be raising a glass when it dives into Saturn’s atmosphere on September 15.
The orbit is still very uncertain but all the astrometry to date (a 25 day arc) implies that it is near parabolic with a perihelion at 1.8au at the end of 2022 or early 2023. This is much less interesting than if it had been in a shorter period orbit since it probably means the that the comet is dynamically new. Such comets tend to have significant activity far from the Sun but then the underperform as they move into the inner Solar System. Still, it is worth observing this comet if you have the equipment. It is very well placed and you don’t often get the chance to image comets which are 16au away.
That Youtube video is fantastic, particularly the thruster plume. Unfortunately I was distracted by other things on Saturday night so forgot all about it. I clearly missed a very nice display.
All three talks are now available to members via the meeting page here.
After yesterday’s meeting at Burlington House Peter Carson has obtained some more astrometry of this object. I’ve added that to the collection and the output from findorb is attached. As I said at the meeting yesterday the period and perihelion date are very poorly constrained at the moment and the residuals aren’t much different if you force the orbit to be parabolic. Astrometry over the next couple of weeks should start to resolve that so we should at least have a good idea of the orbit. It will be a few years before we can even guess how bright it is likely to be when it comes to perihelion in 2023.
Michael. We use a sony voice recorder and a video recorder that goes in the HDMI/VGA path between the laptop and projector. I can’t remember the model number of this but it wasn’t too expensive. Jeremy or Dominic will know the details if you need them. We then merge the audio and video together to produce the final recording.
It was a fantastic weekend with brilliant weather, excellent talks and great company.
Those at Winchester will know that I had set myself the challenge of imaging all four of the relatively bright comets around at the moment even though the pesky Moon was almost full. 41P and 2015V2 are the subject of our current Observing Challenge and they were relatively easy since they were near the zenith, 2017 E4 was a bit more difficult since it was only around 15 deg up at dawn and 2015 ER61 was the hardest of the bunch since it was only 5 deg up when the sky was getting very bright. I used a Megrez 72 refractor at f/4.8 with a Canon EOS600D on a Vixen Sphynx mount set up on the lower football field. I’m pleased to say that after an alarm clock malfunction on the Saturday I managed to get them all on the Sunday. The attached montage shows them all at the same scale. A full-res version of this picture is available via the link.
This comet is running much brighter than expected and it is now reasonably placed for the UK as a morning object low in the east at the start of astronomical twilight. John Toone found it by accident this morning while observing AG Peg and described it as looking a bit like a globular cluster in large binoculars.
Glad you saw it visually Peter. This IC is relatively easy at 8 deg elongation. I have seen Venus at previous conjunctions when the elongation was only 5 deg. You need to be really careful and have a very clear sky. In fact, I also remember trying to see a comet very close to the Sun using one of Denis’ telescopes. We were very careful and one advantage of a dome is that we could block out the Sun so that there was no chance of getting it in the telescope. There is a picture of me doing that somewhere but it is probably best not published for health and safety reasons.
Yes, it was almost certainly in outburst when discovered back in 1952. Unlike today, there were very few people doing astrometry then so the orbit is based on only 7 position measurements over an arc of 26 days. That, and the fact that the orbit will have been changed by relatively close encounters with Jupiter mean that it is very unlikely to be recovered with a specific search. The fact that it has not been picked up by the big professional surveys means that it must be intrinsicly very faint. I’m not sure where Guide 9 gets its data from but it could do with being revised.
The attached ephemeris is from JPL Horizons however, as Martin says, the orbit is very uncertain and it isn’t likely to be near these locations.
Terry Lovejoy’s latest comet, C/2017 E4, is now just visible from UK latitudes (52N). At the end of a long clear night of comet observing I imaged it at 0415 UT when the comet was 11 deg above the horizon and the Sun was 14 deg down. It’s not a very good image compared with observers further south and it only shows the brightest central part of the coma but it is there! Visual observers are putting it around 9th mag but the observing circumstances remain challenging for the UK.
