Observing in really good conditions 22./23.8.2012

Date: 22./23.8.2012
Time: 00:15-02:20
Observing site: Visitor Centre, Seitseminen National Park, Finland
Instrument: L102/1000mm (4” refractor)

NELM: 6,6
SQM: 21,27
Darkness of the background sky: 1
Seeing: 2
Transparency: 2
Weather: Clear sky, calm, no Moon, humid air, 10°C

Objects observed: SS Cyg (visual), U Umi (visual), Messier 56 (visual, sketching)

This session was again really dark, actually it was the new darkest session so far this season! During this session I recorded the best SQM -reading so far, 21,27! Also NELM was really good, 6,6. This time it wasn’t luckily so cold as it was last time, during this session temperature was about 10°C. The sky was mostly clear during the session, although there was some clouds in the sky, but they weren’t causing any major disturbance.

During this session, I was observing SS Cyg again, which is now showing signs of declining brightness. Í estimated that it’s brightness was about 9.2. Another variable star that I observed was U Umi, and i estimated that it’s brightness was about 10,4. Also this star is getting fainter now.

Besides variable stars, I observed deep sky too! It would have been a shame to not observe any deep sky objects because the conditions were so great! This time I observed and sketched Messier 56, a globular cluster in constellation of Lyra.

Messier 56: @ 133x, round, fuzzy nebula, not resolved into stars. Pretty even brightness distribution, no obvious central brightening.

Messier 56 observed with 4'' Refractor
Messier 56 observed with 4” Refractor

Variable star observations:

Date Time Star Mag. Comp.
22./23.8.2012 00.39 SS Cyg 9.2 9.2/9.8
22./23.8.2012 02.10 U Umi 10.4 9.6/10.6

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