Comet C/2013 US10 (Catalina) – December 3rd, 2015

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Another imaging session with comet Catalina.

This time, despite setting up a larger instrument (compared to the 65mm refractor used for the first observation), I had to fight the heavy fog that set onto the field where I was observing. This, combined with the low altitude of the comet and the presence of the Last Quarter Moon made the observation of Catalina very hard. The seeing conditions were also awful. On top of this, some clouds rolled in for about 40 minutes almost cutting down my session to only 10 frames. Eventually, the clouds vanished and 20 more frames were acquired, but with a blue background due to the upcoming dawn.

Equipment used: 8inch F/5 homemade Newtonian (SkyWatcher optics), Baader MPCC, Canon 550D.

30 unguided frames, each a 25 second exposure at ISO 3200 and 1600, were used for the final image.

The session was divided by the clouds into two parts, so the final image shows two positions for each of the background star. The mean acquisition time was 04:10 U.T.

Catalina Dec 3, 2015 color.jpg

The greenish color of the coma and the two tails are observable.

A grayscale version showing the extend of the tails and some structure (fan-shaped tail) a little better:

Catalina BW Dec 3, 2015.jpg

Since the Moon was also visible, an apparent size comparison was possible:


And the last image, a single 20 second exposure showing planet Venus among the background stars, with a lovely golden diffraction pattern:


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