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Thanks to all the speakers and the technical people who put the material online – and of course the organisers too. David Swan
Hello James. I am a fan of imaging transients and noticed this one a few days ago on David Bishop’s website. IMHO it certainly is worth flagging this on the forum – as a (visible) PSN or SN in a Messier object does not occur that frequently. Great image! The weather where I am is atrocious. David
Peter Carson has managed to capture a much better image (see his member’s page). Nonetheless, under poor conditions (wind ESE – straight from sea towards scope (!), and lots of condensation on the corrector in misty air) I acquired five reasonably steady frames. Comphot estimate: mag 10.4 in photometric aperture of diameter 130arcsec – but take this with a pinch of salt.
As Nick has said, the orbit is obviously very well determined. I updated MPCORB in Astrometrica, and the comet was spot on the predicted position.
DDP tends to bloat the stars and make them furry. Here’s a clearer image with the ion tail quite distinct. 12 x 10s, midpoint 05:14:30.
Very nice. Hopefully I’ll be granted a half hour patch of clear skies in the morning some day soon. D
An excellent set of talks. Thanks to all the speakers and those involved in getting the content on the website. David
This is a good question – to which I can’t offer you a good answer! You might want to submit your question to the comet discussion list and Nick James or another will likely pick it up quicker.
I would say that if your plate scale is around 1 arcsec / pixel or below then you might as well 2×2 bin and use the mono pics for astrometry. I’m not sure what you should do if you are correctly sampling or are undersampling.
I look forward to seeing your colour pics of Wirtanen! I’ve just bought a Hyperstar (Christmas brought forward) to give me a wide field of view for the close approach.
Good to hear you are imaging 64P – it’s nice isn’t it? And 38P is moving to a better position.
David
I would consider the Televue Powermate series. I don’t have experience with the 2in versions, but I was very happy with the 1.25in 2.5x Powermate which I used with my f/5 130mm Newtonian.
Thanks Robin. I submitted an image to David Bishop a few days ago now, and I was wondering when the classification would be made. Good job with such a dim one! David
I have been measuring the V mag of this star (about) every week since Gary highlighted it as ‘new’ RCB. My last measurement was V = 14.64 on 2018/09/17 20:49 UT.
I have re-stacked with more stringent quality criteria (FWHM and roundness). The noise is higher, but the stars look more round. Problem sorted I think! I’ve looked back at my determinations of transient locations, and the difference from the survey telescope position in this case isn’t unusual. Experimenting with the fit order doesn’t really change the measured position either.
Yes. Thanks Paul.
The raw FITS files are archived on my external drive, so I can go back and do this. It would be nice to identify the source of the problem, as I may need to modify my workflow.
D
Thanks for the image analysis. So with several ‘winged’ bright stars nearby, it looks like PSF contamination is an unlikely explanation. Maybe an artifact produced by the optics or by something weird associated with frame stacking? Hopefully someone else will image this transient at a good scale and post astrometry.
