Catalogue Generation

The recipes with a _CATALOGUE suffix create a source catalogue from the mosaic using EXTRACTOR. The catalogue includes objects having at least 12 connected pixels above 1.0 $\sigma$ above sky. The catalogue is written in ARK Cluster format, with a field ID in column 0 (this value is typically zero); an object ID in column 1; right ascension in columns 2, 3, and 4; declination in columns 5, 6, and 7; x and y positions in columns 8 and 9; uncalibrated magnitude in column 10; the error in magnitude in column 11; and a quality flag in column 12 (this value is typically zero). The magnitudes are given by the expression $-2.5 \raisebox{-0.4ex}{\rm *}$log10(counts) per second exposure time.

As the final mosaic has varying noise characteristics, with higher noise regions at the edges, the detection limit varies across the mosaic. Fainter objects can be detected in the central region than near the edges and corners.
[_CREATE_SOURCE_CATALOGUE_, _GET_CATALOGUE_NAME_]