M2

Globular cluster in Aquarius, containing about 150,000 stars at a distance of 37,500 light years.   At visual magnitude 6.5, it is just beyond naked eye visibility. The cluster is about 175 light years in diameter and at this distance, spans about 10 minutes of arc in the sky, although long exposure photographs extend this another 5 or 6 minutes. The center of M2 is quite dense and compressed and thus quite bright, with its brightest stars being red and yellow giants of magnitude 13. It seems to be quite old, with an estimated age of about 13 billion years. M2 is approaching the Solar System at a very low velocity of only a tad over 5 km per second. The cluster is in a very elliptical orbit around the center of the Milky Way and varies from a distance of about 23,000 light years to a distance of more than 170,000 light years! The cluster is just barely visible to the unaided eye under ideal conditions and requires a scope of at least 10 inches to fully resolve into individual stars. In my photo below, the track of a faint meteor or more likely, a dim satellite track can be seen in the upper left portion of the image.

Image taken September 5, 2012, with the C-14 operating at F:7 and the ST-8 camera binned 2 X 2. Exposure is 5 minutes, self-guided.

Taken about 4:30 A.M., July 2, 2001.   This is the first good image I obtained with the C-14, using the 237 camera at prime focus with the Fastar optical system.  Exposure was a track and accumulate composite of 8 fifteen second images combined with CCDOPS, at a temp. of -10 C.   I was forced to use the combination of short exposures because of the weather.   Below is a copy of the image processed with Maxim DL.

In November, 2007, I imaged M2 again, with the 402 camera, using a longer exposure to reveal more of the outer parts of the cluster. Unfortunately, the center portion became saturated and could not be resolved. The exposure time was 15 minutes, below:
For a size comparison, the above image is a color exposure taken October 17 with the Nikon operating at F:7 on the C-14.   Exposure is 1 minute on Fuji 800 negative.  Below is the same image cropped to reveal some detail.