Last night was another clear night, that come few and far between here in New Jersey.  I was planning on trying to capture M7, but couldn't point lower to  the south on the Horizon in my driveway, so I decided on M15, my 1st attempt at shooting M15.  When processing this image I found round circles in the image and had to process them out, I tired to do the same with a drizzled image, but for now it was a waste of time, so I abandoned the process and published my first run, which I decided to crop.

Messier 15 (M15), also known as the Great Pegasus Cluster, is a globular cluster located in the northern constellation Pegasus. The cluster has an apparent magnitude of 6.2 and lies at a distance of 33,600 light years (10,000 parsecs) from Earth. It has the designation NGC 7078 in the New General Catalogue.

Messier 15 is one of the oldest known globulars in our galaxy. It has an estimated age of 12 billion years and only 1 percent of the Sun’s iron content. The cluster has an absolute magnitude of -9.2, which makes it about 360,000 times more luminous than the Sun.Messier 15 has an apparent diameter of 18 arc minutes, corresponding to a linear diameter of about 175 light years. The tidal radius of M15 spans 21.5 arc minutes, or about 210 light years from the cluster’s centre.Messier 15 has a density classification IV and is one of the most densely concentrated clusters of its kind. The cluster is notable for its steep central cusp, with an exceptionally large number of stars orbiting what is likely a central black hole.The central density cusp is a result of the cluster having undergone a core collapse, a contraction of its core region. This is a common occurrence in globular clusters as they evolve: Messier 30 and Messier 70also contain a collapsed core. A total of 21 of the 157 known globular clusters in the Milky Way, and possibly 8 more, including Messier 62 and Messier 79, have undergone a core collapse.The core of Messier 15 is very small – about 0.14 arc minutes or 1.4 light years – compared to the cluster’s size. Half the cluster’s mass is concentrated within the central 10 light years, or 1.06 arc minutes. Scientists have theorized that either the cluster contains a supermassive black hole at its core or the concentration of mass is a result of the gravitational interaction of the stars in this area. A survey of the cluster’s inner 22 light years alone revealed about 30,000 stars.The cluster contains more than 100,000 stars, including a considerable number of variables (112) and pulsars (8), neutron stars formed in supernova explosions that occurred when M15 and the universe itself were still young. The only other globulars with more known variables are Messier 3 and Omega Centauri. Omega Centauri, the largest globular cluster in the Milky Way Galaxy, is not included in Messier’s catalogue.The brightest stars in M15 are of magnitude 12.6. They have an absolute magnitude of -2.8, which makes them about 1,000 times more luminous than the Sun. M15 is approaching us at 107 km/s.Messier 15 is home to a double neutron star system, designated M15 C, and the first ever planetary nebula discovered in a globular cluster.The nebula, Pease 1 (K 648), was first observed in 1928. It is one of only four nebulae discovered within globular clusters. It was named after Francis Gladheim Pease, the American astronomer who discovered it. The nebula occupies an area 3 arc seconds in size and has a visual magnitude of 15.5.Two bright sources of X-ray emissions have been detected in M15 by the space satellites Chandra X-ray Observatory and Uhuru. The sources are designated Messier 15 X-1 and Messier 15 X-2. The first one, also catalogued as 4U 2129+12, is the first astronomical X-ray source found in Pegasus constellation.Messier 15 can easily be seen in binoculars and small telescopes, but only appears as a fuzzy patch of light in smaller instruments.The cluster’s stars can be resolved by 6-inch and larger telescopes.Amateur telescopes will reveal an object about 7 arc minutes in size visually.Messier 15 is located 3 ½ degrees west and 2 ¼ degrees north of Enif, Epsilon Pegasi.As easy way to find the cluster is to first identify the Great Square of Pegasus, an asterism formed by the Pegasus stars Markab, Scheat and Algenib with Alpheratz in Andromeda, and then to find Markab, Alpha Pegasi, which marks the southwestern corner.Enif lies about halfway between Markab and the constellation Delphinus, known for its distinctive kite shape.