DES Observational Technique


We have established an edge-to-edge grid of Mosaic fields covering a 13-degree-wide band around the sky centered on the ecliptic. All fields within the band containing stars brighter than 9.5 mag have been deleted, as have fields with fewer than 30 astrometric standard stars (from the USNO A 2.0 catalog) per chip.

Figure X (below) shows a typical distribution of search fields which meet both of these conditions. On any given observing night, we focus our effort on fields within +/-30 degrees of the opposition point.

A sample map of search fields meeting the criteria of the Deep Ecliptic Survey. Each square is the size of a single Mosaic exposure. Declination is plotted along the ordinate; right ascension is plotted along the abscissa. The solid line running from lower left to upper right indicates the ecliptic. The intersection of the ecliptic with the other solid line indicates the location of the opposition point for the date of the chart. The dashed lines are spaced at intervals of 5 degrees.


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