Ptolemy's Cluster (M7)

Posted by dcrowson
on Saturday, May 7, 2016

M7 (NGC 6475 or Ptolemy’s Cluster) is an open cluster consisting of around 80 stars approximately 980 light-years away in Scorpius. It is the lowest messier object at declination -34.8 degrees and was around 12 degrees above the horizon when I imaged it.

NGC 6453, a type IV globular cluster, can be seen around 2 o’clock.

Open cluster NGC 6444 can be seen around 3 o’clock on the edge of the frame.

Luminance – 12x600s – 120 minutes – binned 1x1
RGB – 8x300s – 40 minutes each – binned 2x2

240 minutes total exposure – 4 hours

Imaged on April 8th and 12, and May 5th, 2016 at the Danville Conservation Area (New Florence, Missouri) with a SBIG ST-8300M on an Astro-Tech AT90EDT at f/6.7 603mm.

LRGB - https://www.flickr.com/photos/dcrowson/26268207643/sizes/l

So how many stars can you count in the background?

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