Objective Prism Surveys

The Hamburg sky surveys made on Schmidt plates taken with objective prisms consist of two complementary parts: The northern Hamburg Quasar Survey (HQS) ( b $> 20o, delta > 0o$) and the southern Hamburg/ESO Survey (HES) ( b $> 30o, delta < +2.5o$). The plates of the HQS were taken 1985 - 1997 with the Calar Alto Schmidt telescope, and contain usable spectra with a seeing limited resolution of $45 Å$ at H $gamma$ in the magnitude range 14 $<$ B $<$ 19. The southern plates were obtained with the ESO Schmidt telescope 1990 - 1996, having a spectral resolution of $15 Å$ at H $gamma$ and containing usable spectra in the magnitude range 13 $<$ B j < 18.

The HQS archive contains 1288 plates for 567 fields, while for the HES one spectral plate was taken for each of 428 fields. Plates for both surveys are scanned in full mapping mode by the Hamburg PDS microdensitometer and the digitized database is used for a variety of astronomical applications, in addition to the search for (mostly bright) quasars.

X-ray astronomy became topic of research in Hamburg with the launch of the ROSAT satellite in 1990. A larger effort undertaken is the identification of ROSAT sources on Schmidt plates of the Hamburg Quasar Survey. Based on these identifications several AGN related projects were pursued, involving follow-up observations of selected X-ray sources with ROSAT and optical telescopes.