Messier/type:M21 / open cluster
mag/dia/dist:5.9 / 15' / 4,100 ly
constellation:Sagittarius
date/time/place:Mar 29, 01 / 05:30 / bangkok
trans'y/seeing/l-poll:fair / fair / moderate
telescope:newtonian 4.5" f8.8
eyepieces/power:25mm / 40x
sky atlas page:22
Hopping from M8, in the finder scope M20 & M21 can be seen in the same FOV M20 locates about 3 degree above M8 (north direction) and M21 locates 1 degree north-east of M20. At the observing time, I couldn't separate M20 from sky glow background. M21 appeared as small, loose open cluster, also I observed a little bit nebulosity which should be non-resolvable stars.
Refer to text: 70 stars;detached, strong concentration; large range in brightness; max mag7.3. Extend 15ly;age 4.6 million years. Home
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