M3 is a cluster of about 250,000 stars in the constellation of Canes Venatici. The entire object is fairly huge, about 200 Light Years across, but the dense inner core is only about 11 LY in diameter. It lies at a distance of about 34,000 light years and is believed to have formed about 10 billion yesrs ago, making it a fairly old object even by Astronomical standards. The object is believed to be about 300,000 times brighter then the sun (although of course it appears much fainter because of the great distance). It is not visible to the naked eye but is easily visible through a small scope or binoculars, looking like a much smaller and fainter version of my image.
Constructed from Unguided 40 and 60 second exposures: 40 minutes Monochrome ("L") at 40 seconds/frame, 5 minutes "G" , 8 Minutes "R", 25 Minutes "B". All color frames binned 2x2, taken using my TV "Genesis" refractor and Starlight-Xpresss MX716 camera. Images processed using AIP4WIN and SIPRA (see "My Software"). Images were taken in May 2009.
M3 was actually the first deep sky object I ever try to photograph, my original picture from 6 (?) years ago gives a better idea of what the object looks like through a small telescope:
Object Information from SEDS DataBase, as usual