The northern sky optical cluster survey. II. An objective cluster catalog for 5800 square degrees

R. R. Gal, R. R. De Carvalho, P. A.A. Lopes, S. G. Djorgovski, R. J. Brunner, A. Mahabal, S. C. Odewahn

Research output: Contribution to journalArticlepeer-review


We present a new, objectively defined catalog of candidate galaxy clusters based on the galaxy catalogs from the digitized Second Palomar Observatory Sky Survey. This cluster catalog, derived from the best calibrated plates in the high-latitude (|b| > 30°) northern Galactic cap region, covers 5800 deg2 and contains 8155 candidate clusters. A simple adaptive kernel density mapping technique, combined with the SExtractor object detection algorithm, is used to detect galaxy overdensities, which we identify as clusters. Simulations of the background galaxy distribution and clusters of varying richnesses and redshifts allow us to optimize detection parameters and measure the completeness and contamination rates for our catalog. Cluster richnesses and photometric redshifts are measured, using integrated colors and magnitudes for each cluster. An extensive spectroscopic survey is used to confirm the photometric results. This catalog, with well-characterized sample properties, provides a sound basis for future studies of cluster physics and large-scale structure.

Original languageEnglish (US)
Pages (from-to)2064-2084
Number of pages21
JournalAstronomical Journal
Issue number4 1768
StatePublished - Apr 2003
Externally publishedYes


  • Catalogs
  • Galaxies: clusters: general
  • Large-scale structure of universe
  • Surveys

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

Fingerprint Dive into the research topics of 'The northern sky optical cluster survey. II. An objective cluster catalog for 5800 square degrees'. Together they form a unique fingerprint.

Cite this