Forum Replies Created
-
Posts
-
We’ll certainly try to do this again when we have the opportunity. I’ve just watched a few clips from the meeting on Youtube and the quality is very good. This was a learning experience for us but it worked well and we had around 30 people watching the livestream.
We could livestream this meeting because that the IoP had the facilities and expertise to provide a very good user experience. This is not the case at our other venues. Hopefully we’ll be back at the IoP soon so that we can do this again and, hopefully, some of the other venues we use would be able to offer this in the future.
Thanks again to the IoP for hosting the meeting and to Hazel Collett for the excellent organisation.
Happy Christmas and look out for that comet (and those meteors and variable stars).
Nick.
Are you using background from PSF or background from aperture? I think you should always use the latter since the PSF background estimator needs a much biffer photometric aperture to work properly. They often give very different magnitude zero points.
George. Congrats on another nice discovery. I’m getting 17.4 unfiltered (UCAC-4 R band) tonight (see attached). I think the photometric apertures that you are using in Astrometrica may be a bit small. This may lead to some problems with it estimating the sky background.
Recent magnitude estimates indicate that this comet is not brightening very quickly and latest estimates put it around mag 9. It will get increasingly difficult to observe as its elongation decreases but please try to get more images and estimates as it heads in to perihelion. There is a good set of images in the Comet Section archive.
Lars, The ephemeris from the MPC that Peter gave is about as good as it gets. Any differences in the 1981 ephemeris will be due to a different epoch (B1950 vs J2000) and fewer observations. I’ve attached an ephemeris from JPL Horizons wich is very similar to the MPC one. I’ve also attached a scan of BAA Circular 615 from 1981 March 4 which includes an ephemeris based on only 12 positions over a short arc so you can compare.
Yes there is. You can see it better in the stack attached. This is stacked on stars so the comet is trailed and the background is not yet sorted but it shows the ion tail going out of the field.
Here’s a quick process of a widefield image I took this morning with Denis Buczynski in northern Scotland. I’ll do a better job of processing this later and put the result on my members page. The galaxy is NGC4753.
David – Great image showing the tail. Denis and I managed to get some astrometry on it this morning but the conditions were poor so our images are rubbish.
Official designation is C/2018 V1.
Probably 7.5 – 8.0 this morning. Any predictions will be very unreliable since it could be in the final stages of a bright outburst or not. Getting up early to observe it is the only way to find out!
Owen. Yes, Andrew Robertson and Peter Carson had a good view through Andrew’s 18-inch telescope at Haw Wood. They commented that the comet was bright and easy.
The latest ephemeris is here using all astrometry I have so far. I’ve done this starting 60 days before now and the positional uncertainties are now quite small. The comet has been at a small elongation for all of this time and was discovered when it was at its largest elongation. This is now decreasing. The comet has a small q (0.39 au) and is brightening rapidly.
Please try to observe this comet at any opportunity.
Nick.
Denis and I managed to image this comet this morning from Scotland. I’ve just posted a very quick process of one of the images here.
I gave a talk to Newbury Astro Soc last Friday when I said that it was now very unlikely that we would get visual comet discoveries. How wrong I was! Congratulations to Don and the other independent discoverers of this comet.
An ephemeris based on all the available astrometry up to this morning is here. It was produced using Bill Gray’s FindOrb. These elements are still very uncertain but it looks like it is heading to a perihelion in early December. It is currently moving south and the elongation is decreasing so it will become increasingly difficult to observe. From the UK it is currently a morning object amongst the galaxies in Virgo. The column headed “/sig gives some idea of the position uncertainty (in arcsec).
Any observations (astrometry, photometry or images) would be gratefully received.
Good to see scientists getting this recognition and thanks for the link. It was always a shame that Isaac Newton made it to the pound note just before it was scrapped. I wonder if they could bring him back for the £50?
I like the “draw your own banknote” link. I could do that. I doubt my local shop would accept it though!
Hi Helen,
David’s advice is pretty much spot on.
I would de-bayer and use the green layer in Astrometrica as pseudo-V, i.e. set Astrometrica to use V band or the Gaia G band. You can then do astrometry and photometry. Have a look at the comphot page if you want to have a go at photometry. Depending on your pixel scale you can do the de-bayering by linear interpolation or simply by binning the two green pixels in each set of four. The latter is probably more photometrically correct. I have done photometry and astrometry using an ASI294MC camera and get good results.
Let me know if you need more detail on this. I hope that you decide to submit images and data to the section.
Nick.
Ella, There are lots of geosynchronous satellites which show up in southern Orion and which can be quite bright near local midnight. The geostationary arc passes below the Horsehead but old, out-of-plane satellites can show up there. These objects trail at around 0.25 deg / minute and appear to move westwards relative to the star background. Here’s an example near M42 from a wider field image.
Michael,
Very many thanks from me as well. An excellent meeting showing just what amateurs can do now in meteor research. Sorry that we had to rush off at the end. I do need a new satnav though, either that or start looking at maps again. It sent me up the wrong end of Dunsink Lane which was a bit scary…
Nick.
And here it is tonight. It is currently moving at just over 23 arcsec/min.
