Uploaded 30-Aug-11
Taken 1-Sep-11
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6 of 21 photos
Photo Info

Dimensions1600 x 1066
Original file size1.48 MB
Image typeJPEG
Color spacesRGB
Date modified1-Sep-11 11:30
Comet Garradd & M71

Comet Garradd & M71

Canon 7D, C11 + 6.3, EQ6 EQMOD, guided with 9x50 Finder Scope, DSI Pro 2
8 x 180 seconds @ 1600 ISO
7 Dark frames
20 Flats
50 Bias
Total Exposure: 24 minutes
Captured with BackyardEOS
Calibrated with the Comet Stacking routine in DeepSkyStacker

Grand Prize Winner SkyNews 10th Annual Photo Contest
Winning Entry August 2011 Digital Astro Group Challenge
Featured image BackyardEOS home page
Featured in an article by Michael Moyer of Scientific American: Next Year A Spectacular Comet Will Fly By Earth

Messier 71 (also known as M71 or NGC 6838) is a globular cluster in the constellation Sagitta. It was discovered by Philippe Loys de Chéseaux in 1746 and included by Charles Messier in his catalog ofcomet-like objects in 1780. It was also noted by Koehler at Dresden around 1775.
M71 is at a distance of about 12,000 light years away from Earth and spans some 27 light years across. The irregular variable star Z Sagittae is a member of this cluster.
M71 was long thought (until the 1970s) to be a densely packed open cluster and was classified as such by leading astronomers in the field of star cluster research due to its lacking a dense central compression, and its stars having more "metals" than is usual for an ancient globular cluster; furthermore, it's lacking the RR Lyrae "cluster" variable stars that are common in most globulars. However, modern photometric photometry has detected a short "horizontal branch" in the H-R diagram of M71, which is characteristic of a globular cluster. The shortness of the branch explains the lacking of the RR Lyrae variables and is due to the globular's relatively young age of 9-10 billion years. The relative youth of this globular also explains the abundance of "metals" in its stars. Hence today, M71 is designated as a very loosely concentrated globular cluster, much like M68 in Hydra. M71 has a luminosity of around 13,200 suns. (from Wikipedia)