Photopic Sky Survey
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Nick Risinger decided it was about time that somebody created a single image of the entire night sky. So, with the assistance of his retired father, he dedicated a full year to photographing and then stitching together data from 37,440 separate exposures. The pair covered 45,000 miles by air and 15,000 miles by land. Braving thin, bone-chilling mountain air and wild animals in the U.S. western states and the Northern Cape in South Africa proved in some ways to be the easy part. The overwhelming task of sorting and processing the images required the application of some pretty sophisticated software, and a huge learning curve. Says Nick, "I divided the sky into 624 uniformly spaced areas and entered their coordinates into the computer which gave me assurance that I was on target and would finish without any gaps. Each frame received a total of 60 exposures: 4 short, 4 medium, and 4 long shots for each camera which would help to reduce the amount of noise, overhead satellite trails and other unwanted artifacts."

An array of six cameras, each with a unique filter, was mounted on an equatorial base so that it could track the movement of the stars across the sky. The result is a gargantuan 5-Gpixel image. The entire file can be viewed online in the form of an interactive Flash presentation. The basic version comes without any labels, but there is also a labeled version that superimposes constellation, nebulae, planet, and galaxy outlines and labels over the base image. Details of the entire effort, including equipment and software, is listed on Nick's SkySurvey.org website. An even more detailed story ("For All the Night's Stars") appeared in the February, 2012, edition of Sky & Telescope magazine, which is where I first saw it. With the fairly recent culmination of relatively low cost telescopes with 12" and larger objectives, low-noise imaging cameras, and super-accurate tracking mounts, amateur astronomers are now creating astrophotos that not just rival, but exceed the quality of those formerly the realm of million-dollar telescopes and hypersensitized, high ISO film and the need for expert film developing skills. NASA is now actually providing stipends to some amateurs (making them pros, technically) for conducting surveys of specific regions of the sky - especially for detecting objects that are in orbits that will cross dangerously close to the Earth.

Photopic Sky Survey w/Labels

Posted January 17, 2012