This massive conglomeration of stars was discovered by Edmund Halley in 1714 and consequently cataloged by Charles Messier on June 1, 1764. With a collective apparent magnitude of 5.80 and a size of roughly 23 arc-minutes, this globular cluster is easily visible with a small telescope. In this image, 2 galaxies are also visible. To the lower right of the cluster is the 12th magnitude edge-on spiral NGC6207. Between M13 and NGC6207 is the very tiny 15th magnitude IC4617.
Telescope: Astro Tech AT8IN 8” f/4 Newtonian
Accessories: Baader MPCC
Mount: Orion Atlas EQ-G controlled by EQMOD
Guiding: TS-OAG9 Off-axis, using Orion StarShoot AutoGuider
Camera: Canon Digital Rebel T1i, Hap Griffin Baader modified
Filters: IDAS-LPS EOS Clip (N1&N2) Astronomik CLS-CCD EOS Clip (N3)
Exposure: 88 x 180s @ ISO 400 (4hr. 24min.); 60 x 10s @ ISO 400 + 30 x 30s @ ISO 400 + 30 x 60s @ ISO 400 (for the core)
Acquisition: ImagesPlus 3.83 Camera Control
Processing: ImagesPlus 3.80a – Calibrated, registered, min/max averaged, DDP
Post-processing: Adobe Photoshop CS4; Gradient XTerminator; Noise Ninja; Noel Carboni's Tools
Date(s): May 22, 23 & 24 2010
Temperature(s): N1:72ºF (dropped to 69ºF); N1:82ºF (dropped to 76ºF); N3:78ºF (dropped to 74ºF)
SQM reading (begin - end): N1:18.71 - 18.82; N2:18.34 - 18.66; N3:17.96 - 18.04
Moon data: Waxing Gibbous - N1: 74%(79º a/s); N2: 83%(73º a/s); N3: 91%(68º a/s)