Comet 41P Leaving the M108 and Owl Nebula Area

Comet 41P on Mar 23, 2017. 40 x 180 sec @ ISO 200, TV-85 at F/5.6, Canon T3.

On the night following the encounter between M108, Comet 41P and the Owl Nebula, the comet was still in the field of view of my setup, so I went back for seconds.   I just couldn’t pass up the opportunity to shoot a comet conjunction again!

I went with 3 minutes sub-images at ISO 200, since the 1 minute ISO 800 subs were too cooked by the LP for my taste.  Unfortunately, the sky was not as transparent as the previous night and that half-stop of underexposure was needed to get around that.  The trade-off was I didn’t get as much of the comet’s coma.   Oh, well.

Also, at that exposure length, the comet’s pseudo-nucleus trailed a bit, since it is moving with respect to the Earth and stars and slowly picking up speed as time goes on, to boot.   It was not enough to notice if I carefully over-exposed it a bit in processing to make it fatter, luckily.  Check the star streaks version, which I did not overexpose, and you can see how far the comet moved in 3 minutes:

Comet 41P on Mar 23, 2017. Star Streaks version.

A Televue TV-85 w/0.8x focal reducer/field flattener, a Canon T3, my laptop running EQMOD, driving my Atlas EQ-G mount and PHD2 Guiding with an Orion StarShoot guider/Orion Ultra-Mini guidescope was some of the equipment used.


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