M13 Hercules Globular Cluster M13 is a rather dense globular cluster that is sometimes visible with the naked eye. It lies 25,000 light-years from Earth, is 145 light-years across, and contains over 300,00 stars. Galaxy NGC6207 appears innocently at top-left, yet is over 200 times larger than M13, lying about 40 million light-years away. North is at the top. 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 (90) 120 sec @ gain=80, RGB: each channel (10) 120 sec @ gain=80 Software: Nebulosity, PixInsight Comment: 06-05-2021, Tierra del Sol, CA, good conditions, RGB gain setting was mistakenly set too low.