[BAA Comets] Comet 74P near M66 and M65

[denis buczynski]

Hi Mike,  
Thanks for the image of 74p,it will be entered into the BAA Comet Archive at the next visit. It would be best to submit regular coemt images to cometobs at britastro.org rather than the discussion list. The discussion list is provided as a platform for members to introduce subjects for discussion or ask questions of queries. 
I am not familiar with the Maxim/Pinpoint astrometry function. I use Astrometrica for my astrometry. The difference between you results and the ephemeris is probably due to the ephemeris needing to be updated. The reason for making the astometric measurement is to provide new astrometic data to be used for orbit and ephemeris update.Comets are moving through the solar system under a variety of influences and their exact position at any one time cannot be predicted.I notice that you mentioned that you were having focus problems with your system. Looking at your image it seems to me that the problem you are have with flare to one side of all the images across the field is likely to be due to a squaring on error (ie the ccd is not square on to the optical axis of the telescope) I am sure you will be able to adjust this and get rid of the flare you see on all the stars. You have a very nice set up for comet imaging with a quality telescope and ccd camera.I hope all this helps, keep sending the images.Denis Buczynski
 


      From: Mike Paling <mikepaling at madasafish.com>
 To: comets-disc at lists.britastro.org 
 Sent: Friday, 11 May 2018, 11:17
 Subject: [BAA Comets] Comet 74P near M66 and M65
   
I am attaching a jpeg of Comet 74P taken on 4th May 2018 Hopefully not too large and it has the correct designation and that I have sent it to the correct place.

My imaging took place during a single evening ....
Equipment: APM LZOS123/780 f6 refractor and APM Flattener
Camera:     Moravian G2 8300 Mono CCD
Subs on image taken on 4th May 2018:          20 x 100sec CLS subs
Software:   MaximDL and Photoshop
Location:    Garden Observatory 15 miles north of Nottingham.
I ran my processed FITS image through the "Maxim/PinPoint DC3" Astrometrric process ... 
and compared my measurements with an online ephemeris calculator (The Sky 
Live) and found a slight disparity between them as follows;

Maxim/PinPoint Coordinates: 11h 20m 02.96s      +12h 53' 10.7"
The Sky Live Coordinates:       11h 20m 02.2s        +12h 53' 14.3"

They are both very similar .... but am I doing something wrong here?

Regards
Mike Paling

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