Forum Replies Created
-
Posts
-
PSF photometry works well in crowded fields but the separation of these stars is only 2.9 arcsec so getting good enough focus and tracking to ensure that the PSF of each object is not too blended needs a bit of work with an amateur telescope from sea level in the UK. My image was at a scale of 0.28 arcsec/pix and had a star FWHM of 2.2 arcsec so the stars are reasonably well separated but that was on a night of good seeing. CMOS cameras allow selective stacking a lot of short exposures so a strategy similar to that used by planetary imagers is probably worth trying.
I ran source extractor on this image and it showed that V482 Cyg was about 0.2 mag fainter than the companion so probably about 15.2 unfiltered at the moment. The star is likely to be very red though.
This star has now faded to around mag 15. Gary prompted me to look at my images since my magnitude estimates of this star were too bright as it faded. One of the problems with automating everything is that I don’t often look at images or the data derived from them and there is a fairly bright star only 7 arcsec to the SW which was within my photometric aperture. The AAVSO VSX does warn about this. Looking in detail at my unbinned images tonight there is also a 15th mag star only 3 arcsec to the NW of the variable and this will generate significant errors at the current level. This is not mentioned anywhere and I haven’t seen it on other images since it is normally swamped by the bright variable. It is in Gaia EDR3 (a demonstration of how good the optics in that spacecraft are). It is worth considering if you are doing photometry of this star at the moment.
Attachments:
This comet continues to fade and become more diffuse following its outburst on Aug 1. Thank you to all of you who have sent in observations. Please keep observing this object as it expands and fades.
The remarkable weather in SE England means that I have managed to image it every night since the outburst was announced on August 6. My lightcurve and a rather jerky GIF showing the development is attached to this post. The comet has now faded to around 15.7. Still a long way to get back to its ephemeris magnitude of 19.5.
Attachments:
I think David’s point is a good one. I much preferred the previous behaviour where, once you were logged in on a particular machine, you were logged in forever. I know that it is only a few extra clicks but it does mean that there is more of a barrier to replying and interacting with content than there used to be.
That’s true but I was thinking of something with a bit more mass and capability like a small interstellar space probe. Accelerating charged particles to a significant proportion of the speed of light is relatively easy. Accelerating a spacecraft, even a very small one, is a lot harder.
I mentioned this star during the Sky Notes at the BAA meeting in London today. Here is an image taken when I got home. It is unfiltered so the star is still quite bright. I assume that, a bit like R CrB, it will be quite red when it fades.
Attachments:
That’s true when z is cosmological but the point I was trying to make is that you can have z > 1 without having to invoke the expansion of space or any non-flat geometries. The article implies that you can’t.
Headline on the front page of the site today from Jim Rowe (https://britastro.org/2022/12th-may-fireball). It looks as if this one might have dropped 100g or so of meteorites over a rather hilly bit of South Wales. An excellent piece of work by all of the camera networks in UKFAll.
I just caught the very beginning of the trail on my SW facing UK004F camera at Chelmsford. This is the streak on the right side of the attached image. The GMN trajectory solver has a trajectory from UK0002, UK000W, UK003N, UK004F and UK004X which you can see here (https://tammojan.github.io/meteormap/) if you select the latest_daily solutions. It was also picked up by 3 French and 2 British cameras of the Fripon network and their analysis is here: https://fireball.fripon.org/displaymultiple.php?id=17507.
Attachments:
Yes, nothing there that I can see.
Attachments:
Cees Bassa responded to my video pointing to this tweet from Jonathan McDowell:
https://twitter.com/planet4589/status/1520284820450025472
It was the de-orbit burn for the Angara AM second stage launched from Plesetsk yesterday.
It is one of my favourite books too. Lovely descriptions of a lost time. I bought a second hand hardback of the 1967 edition a while ago for around 50p.
$550K for a big house and ten acres seems a steal but it’s not selling. I’ve just had a nose on Google Streetview. Looks very nice although there has been a lot of development around there since Peltier’s day.
I was honoured to speak at Ron’s funeral on Monday. It was very well attended and many BAA friends were present. An obituary will appear in the Journal in due course but, for now, I attach my tribute.
It was a brilliant weekend and my personal highlight was the Steve and Dave double act on Sunday. A very entertaining presentation about the Crayford Dobsonians. All the other talks throughout the weekend were great too. Shame I missed the Friday night.
Thanks very much to Ann and Alan and everyone else involved in arranging it.
I think it is at least the sixth this year.
Have a look here for an up-to-date list. They often don’t get announced in ATELs.
Currently TNS[/url] is the main database now but some discoverers still post on the TOCP.There tend to be several novae a month in M31 but a lot of people are looking for them so it is hard to claim a discovery. George Carey got AT2022eng recently along with Kamil and the Czech team.
I’m not surprised it got silly. The slug was an odd one though. It was the unit of gravitational mass in the FPS system but I don’t think it got used much.
Thanks for explaining that Dominic. I know that a huge amount of work has gone into the new site and it will take some time to iron out the problems but I didn’t know whether this was by design or not.
This was an interesting event. A few minutes before impact it would have been visible at around 11th magnitude moving rapidly across the sky as seen from the UK.
I like examples of NTUs (non-technical units) when describing the characteristics of astronomical objects. Bill Barton alerted me to this classic example in the Mail Online.
Attachments:
