M3 Globular Cluster M3 was the first Messier object to be discovered by Charles Messier (M1 and M2 were already known.) Boasting around 500,000 stars, it measures 90 light-years across and is located about 34,000 light-years from Earth. It is perhaps the most studied of the globular clusters. Scope/Mount: TS-Optics PhotoLine 130mm F7 APO Refractor with Astro-Tech AT2FF Field-flattener, Celestron CI-700 Mount Camera: ZWO ASI1600MMC monochrome with ZWO LRGB filters Guiding: QHY5L-IIM through Orion Thin OAG, PHD guiding software Exposure: L (30) 120 sec @ gain=80, RGB: each channel (10) 120 sec @ gain=139 Software: Nebulosity, PhotoShop CS2 Comment: 04-25-2020, Tierra del Sol, CA, good conditions.