The APS North Galactic Pole Survey

The APS North Galactic Pole Survey is a isophotal diameter-limited catalog of galaxies located on POSS I plates within 30 degrees of the North Galactic Pole. This region covers 98 POSS I fields. The survey can be summarized as follows:

• Contains all galaxies with O or E major-axis diameters greater than 10" (safely above the size limit of the reduction software)
• In two colors: O (blue) and E (red)
• O-E Colors available for all cataloged objects
• Work has been done to remove the following contaminants:
  • Plate Scratches and Flaws
  • The halos around bright SAO stars
  • Ghost images of bright SAO stars (< 5.1 magnitude)
  • Globular clusters (merged images are classed as non-stellar)
  • Multiple detections of patchy light around bright galaxies.
  • Multiple detections of some known low surface brightness galaxies
• Image parameters for each object include:
  • magnitude
  • position angle
  • ellipticity
  • mean surface brightness
  • C21, C32, C31: concentration indices of the images
  • Reff: The half-light radius of the galaxy<

Current Status:

The current version of the catalog (constructed May 28, 1998 using 93 of the 98 fields, see Figure 2) contains:

A map of the average surface density of galaxies in 15 arcminute boxes is shown above (Figure 1). The maximum density of galaxies in the current map is roughly 1600 galaxies per square degree.

Expected Final Status:

The final version of this galaxy survey of the NGP region will be constructed later this summer using the revised APS Catalog of the POSS I (StarBase 2). StarBase 2 has improved non-stellar classification, positions, and magnitudes (A more complete description of the changes can be seen at poster 55.09). The final survey will be made available online as a binary datafile.

Go forward to Motivations for this Survey