Observing Comet C/2013 US10 (Catalina)

Date: 23./24.12.2015
Time: 07:15-07:50
Observing site: Friitala, Ulvila, Finland
Instrument: 10×50 binoculars, L80/400mm (4” refractor)

NELM: 5.0
SQM: –
Darkness of the background sky: 5
Seeing: –
Transparency: –
Weather: Clear sky, full Moon setting in NW, light sky, twilight at the end of the observing session, very mild weather, no snow

Objects observed: C/2013 US10 (Catalina)

Finally also I was able to observe the anticipated comet C/2013 US10 (Catalina). I was observing the comet in Friitala, Ulvila, Finland in the morning of Christmas eve.

I was able to locate the comet easily just 12 degrees south of Arcturus. With my 10×50 binoculars, the comet appeared as small, fuzzy star with a little bit brighter core. There was no tail visible visually. With the binos, I estimated that the size of the coma of the comet was about 3,3′ (estimated with the separation of stars A and B in picture 1) and brightness about 6,2 magnitudes (estimated with out of focus -method).

I observed the comet also with my 3” rich field refractor. With this instrument, the comet appeared also as a small fuzzy nebulous spot that looked like many unresolved globular clusters with this instrument. There was no tail visible with this instrument either. With the refractor, I estimated that the degree of condensation of the coma was 6, and size about 4,6′(estimated with the separation of stars A and B in picture 2).

The comet was easy with the binoculars, but ideally it should be observed with larger instrument, perhaps with about 4” refractor or reflector.

151223-24_Catalina_10x50
Picture 1. Comet C/2013 US10 (Catalina) observed with 10×50 binoculars.
151223-24_Catalina_L80-400mm
Picture 2. Comet C/2013 US10 (Catalina) observed with 3” refractor.

 

 

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