MAPS - Minnesota Automated Plate Scanner Catalog of the POSS I


Welcome to our on-line catalog of millions of stars and galaxies. This data is derived from the Minnesota Automated Plate Scanner - MAPS - scans of the National Geographic-Palomar Observatory Sky Survey (POSS I) blue (O) and red (E) plates. Please read the documentation carefully before using the MAPS. You can use the APS POSS I object catalog, make a finder chart, identify a POSS I field on the sky, or obtain information about each separate field.

About the MAPS - What is the Catalog?

The Minnesota Automated Plate Scanner (MAPS) Catalog of the first epoch Palomar Sky Survey (POSS I) is derived from our digitized scans of glass copies of the blue(O) and red(E) plates of the original Palomar Observatory Sky Survey for the 632 fields with Galactic latitudes |b| > 20° (see the figure below). The scans are done in threshold densitometry mode, recording all pixels above the scanning threshold. The operation of the Automated Plate Scanner (APS) and the scanning procedures are described in detail in Pennington et al. (1993). The MAPS Catalog of the POSS I contains coordinates, magnitudes, colors, and several other computed image parameters for all of the matched images on the blue and red plates for nearly 90 million stars and galaxies down to fainter than 21st magnitude (in the blue). The stellar and non-stellar images are separated using a neural network image classifier, described in Odewahn et al. (1992, 1993), that has been trained to the plate limit. The pixel data have also been archived and include all of the matched images in the Catalog of objects, as well as the unmatched images above the noise threshold.

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