Noctilucent clouds in the sky of Turku

Observing session #2/11-12

In the night between 25./26.7.2011 there was a notable noctilucent cloud display visible in the sky of Turku. My observing place was Kerttulinmäki -hill near the downtown of Turku. I was making observations of this display in 02.00-02.15. During that time, the clouds were glowing in the northern sky, where their highest altitude was about 30 degrees. The clouds were very bright and they had a typical blueish colour. The display was mostly consisted of horizontal bands.

The night sky has already got quite dark now in late July. When I was making observations of NLCs I also made measurements with SQM -meter. I got readings of 17, which means that the sky is still quite light but not anymore as light as it is during the midsummer.

Also I was watching The Moon and Jupiter with my 102/1000mm Celestron in Kupittaanpuisto -park. This was my first time, when I was watching any celestial objects under this dark skies. Particularly I was watching the Jupiter and The Moon to check the amount of chromatic aberration in my scope. With The Moon, I didn’t see practically any signs of chromatic aberration, but there was a notable blue glow as a sign of chromatic aberration around Jupiter. But this blue glow wasn’t intefering too much, and I think it might be possible to cut it down with some suitable fringe killer -filter.

Summary of obs session #2/11-12
Date: 25/26.7.2011
Time: 02.10-04.00
Place: Turku, Finland
Instruments used: L102/1000mm, naked eye
Objects observed: Jupiter, The Moon, NLCs
Conditions: NELM: 4.0, SQM: 17.03, partly cloudy, light sky, warm air

Noctilucent clouds were glowing in the sky of Turku in 25./26.7.2011

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