M15, Globular Cluster in Pegasus

M15, NGC 7078,  Size 12.3' x 12.3', Magnitude 6.40,Constellation: Pegasus 

Image Details:

• Scope: 1995 Celestron Ultima 8 OTA.
• Mount: Celestron AS-GT (goto CG5).
• Camera: Meade DSI Color.
• Configuration: f/3.3 focal reducer, no spacers, visual back/1.25" nosepiece.
• Effective Focal Length: 812mm, f/4 approximately.
• Exposure:  20 images @30 seconds.
• Filter: Meade IR blocking filter.
• Acquisition: Meade Envisage. Quality = 30%.
• Guiding: None.
• Location: Stargate Observatory, Fairhope, Alabama
• Date: 4 June 2005.
• Post Processing: Meade IP.
• Photoshop: Levels, unsharp mask, color balancing, .jpg conversion, star size reduction, color noise reduction.

Good, old M15 is on every amateur's must-see list every fall. In addition to its blazing core, 8  inch and larger scopes can resolve at least some of its stars under very poor conditions.

This globular star cluster, which may lie about 35,000 light years from us, is notable for a couple of reasons. First, it's quite easy to locate, being only 4 degrees from bright Enif, Epsilon Pegasi. The cluster is also easy to see, even in the city with small scopes, due to its amazingly bright core. The fact that it is fairly compact and composed of stars of magnitudes 13 and dimmer means a 6 inch telescope at high magnification will be needed  to resolve many stars. Why is the core of this glob bright? M15 is a source of X-rays, leading astronomers to hypothesize that a black hole lies at its center. Scientific opinion as to the existence of an M15 black hole has gone back and forth over the years, however.

One of the first DSI shots I was really pleased with. It was helped by the fact that I left the IR filter in place (or forgot to remove it). Despite the heavy light pollution, the DSI delivered a picture I'm still happy with.

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