QUASARS; SPATIAL DISTRIBUTION; UBV SPECTRA; BACKGROUND RADIATION; BLUE STARS; GALAXIES; RED SHIFT; ULTRAVIOLET ASTRONOMY; ASTRONOMICAL PHOTOGRAPHY
Abstract :
[en] The density of quasars in a control field of the sky selected to be free of bright galaxies is investigated in order to derive a value for the average background density of quasars and to analyze quasar distribution within the field. Schmidt plates were obtained in the ultraviolet and blue for a control field surrounding SAO 45758 at R.A. 15 h 49 min, declination plus 48 deg 38 arcmin. Examination of the spectra of 25 of the 137 objects found to exhibit an ultraviolet excess reveals 12 of them to be quasars, indicating a quasar density of 6.7 plus or minus 0.9/sq deg down to a limiting magnitiude of 20 over the 19 sq deg area of the field. This value is noted to be in agreement with previous values of quasar background density deduced for other regions of the sky. Large fluctuations of quasar density are found, however, within the field which may be correlated with groups of intermediate brightness galaxies.
Disciplines :
Space science, astronomy & astrophysics
Author, co-author :
Arp, H.; Mount Wilson and Las Campanas Observatories, Pasadena, CA
Surdej, Jean ; Université de Liège - ULiège > Département d'astrophys., géophysique et océanographie (AGO) > Astroph. extragalactique et observations spatiales (AEOS)
Language :
English
Title :
Quasars in a control field far from bright galaxies