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C/2012 S1 ISON with FSQ-106ED and Reducer QE 0.73x November 22, 2013UTC | by hirocun
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C/2012 S1 ISON with FSQ-106ED and Reducer QE 0.73x November 22, 2013UTC

It was a nice experience to image the comet, low in the east after the beginning of twilight. The altitude of the comet was 2.1 degrees at the beginning and 7.0 degrees at the end. I took several sets of exposure according as the sky got lighter. Blue was weaker than usual at the altitude, and the frames looked yellowish red, the the color of twilight cloud. The yellowish color of the tail is mainly due to the effect, though I believe that there was emission of sodium partly. The coma looked elongated in north to south direction. The diameter of the coma looked about 80 arcseconds, and it looked about 22 arcseconds in the brightest part. North is up, and East is to the left.

 

equipment: Takahashi FSQ-106ED refractor with Reducer QE 0.73x at f/3.6 and Canon EOS 5Dmk2-sp2, modified by Seo-san on Takahashi EM-200 temma 2 jr. equatorial mount autoguided at the center of the condensation of the coma with side by side mounted Takahashi FS-60C, Starlightxpress Lodestar Autoguider, and PHD guiding

 

(main frame in black and white)

exposure: 15 times x 30 seconds at ISO 1,600 and f/3.6

First exposure started at 20:04:04, 11 minutes after the beginning of twilight and the last at 20:13:10 November 22, 2013UTC.

 

(imposed frame in color)

exposure: 14 times x 4 seconds and 12 x 2 seconds at ISO 1,600 and 21 x 1 second at ISO 800 and f/3.6

First exposure started at 20:20:45 and the last at 20:32:51 November 22, 2013UTC.

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Taken on November 20, 2013