-5 x 240 sec subexposures, iso1600, processed with 30 dark and 30 bias frames
-2x drizzle, 25% area crop.
-Software: PHD2, DSS, XnView, and StarTools v 1.3 and 1.7

Messier 5, M5, NGC 5904 Serpens

M5 was first documented by Gottfried Kirch and his wife Maria in 1702, then rediscovered by Messier in 1764, who thought it to be a nebula. It was first resolved into stars by Herschel in 1791. With integrated apparent magnitude of 6.0, it is easily identified with binoculars, but a 5-8 inch telescope is required to begin resolving individual stars, the brightest of which are of magnitude 12.2. The cluster is composed of 100 to 500 thousand members, distributed over 20 arcmin in angular size, or 165 LY in actual diameter. At least 105 members are known to be variable. Most of them are short term RR Lyrae type or "cluster variable stars". M5 is located at the approximate distance of 24,500 LY, and is thought to be between 10.5 and 13 billion years old.