Monday, June 7, 2010

The Lord's ring - NGC 6720

Sketch of the Ring nebula (M57, NGC 6720)
5 June 2010, 21:02 UT
200mm SCT f/10, light pollution filter
80x, 160x, seeing 7/10, trans 3/5

M57 is situated between Beta and Gamma Lyrae. Through the telescope the ring glows against the dark background, having a darker middle. To the east is a 12-mag star. This Messier object is a planetary nebula, and is one of my favourite deep sky objects in the summer sky.
This is my first sketch of M57. I used averted vision to notice the subtle features of the slightly elongated nebula. After about 10 minutes viewing time (for dark adaptation), I started to notice that the glow of the outer ring is slightly more intense on opposite sides, rather than distributed uniformly. The ring's glow had a slight faint of blue, but it was hard to determine exactly. The central star was not visible even when using the light pollution filter. For amateurs, it is always a challenge to identify the faint central star and one needs to have very good sky conditions in order to detect it.
Below is a digital scan of high power sketch of the ring using graphite pencil on white paper (110gms) showing the differential glow of the outer ring against a slightly darker hollow centre.


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