M13 - The Great Hercules Cluster

23:07 19/4/2010 UTC

After premature end with M106 I had a short opportunity to continue imaging before dawn. I could have realigned to M106, but went easy route instead. Hercules was well up already and I had all the gear up and running for a last hour of imaging this season - in an absolute darkness. Moon was already set and SQM hit the nights record at 21.32. I paid a careful attention to focus and shot RGB in full resolution. M13 is surprisingly big, even in my widefield gear. This image is a 50% center crop from the whole field. So, this is it - my final (deepsky) image from this season.

Camera: Atik Instruments 4000LE | Telescope: Skywatcher ED80 Pro 80mm f7.5 refractor, William Optics 0.8x focal reducer | Mount: Vixen GP-D2, Boxdoerfer PowerFlex MTS-3SLP drive controller | Filters: Baader 2" LRGB Filter Set | Guiding: The Imaging Source DMK 21AU04.AS CCD camera, Orion ShortTube 80mm f5 refractor, Stark-Labs PHD Guiding | Exposure: LRGB 3x240s (18m) each unbinned, CCD @ -25° Total exposure 54m | Software: CCDWare CCDStack, Adobe Photoshop CS4, Stark-Labs Nebulosity 2 | Location: 60°44'00"N 26°12'46"E (Tähtikallio Observatory/Artjärvi, FI) | Background sky brightness (SQM): 21.32 mag/arcsec² | Image Field: 53.08 x 53.07 arcminutes | Image Center: Ra 16h41m40s Dec +36°27'09" |