[BAA Comets] Comet 74P near M66 and M65

[Peter Carson]

Hi Mike,
That’s a very nice image.  

If you haven’t already, send it to Denis Buczynski at cometobs at britastro.org so it gets included in the BAA Comet Section archive. The archive can me found at http://www.britastro.org/cometobs/
I’m not familiar with “Sky Live” but don’t think you should be worrying about the very small discrepancy between your measured position and the predicted position. At your imaging scale the difference amounts to a fraction of a camera pixel in RA and about 1 pixel in Dec.  
If you want to do really accurate astrometry I suggest you use software called Astrometrica. See http://www.astrometrica.at/ its quite difficult to set up but once you’ve worked that out then it dead easy to use and produces measures to a fraction of a second of arc.
Keep up the good work.

Peter Carson



From: Mike Paling 
Sent: Friday, May 11, 2018 11:15 AM
To: comets-disc at lists.britastro.org 
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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