Searching the sky

The paper presents an image-recognition software for astronomy pictures brings professional and amateur astronomers together. Astrometry.net´s search software begins its analysis by looking for the brightest stars in the image and then uses sets of four such stars to draw four-sided shapes that is called quads. Each quad is like a fingerprint for a particular part of the sky. Rather than trying to find a perfect match, the program looks at many possible matches in a database of more than a billion stars. For each matching quad, the computer compares surrounding stars in the image to those predicted by information in the database and reports a successful match only when the stars´ positions correspond with little discrepancy.