First Cycle 4 multiwavelength observations of the gamma-ray quasar PKS 0208-512

Document Type


Publication Date



We present first results of CGRO Cycle 4 multiwavelength observations of the gamma-ray quasar PKS 0208-512. A bright, variable gamma-ray source, PKS 0208-512 has been detected numerous times by the EGRET experiment aboard the CGRO, possessing one of the hardest spectra observed to date. The recent COMPTEL observations of Blom et al. (1995) indicate that PKS 0208-512 may belong to a new class of AGN that flare at MeV energies. During the current CGRO Cycle 4 observing cycle we have obtained observations of PKS 0208-512 at high- and mediumenergy gamma-rays with the EGRET and COMPTEL instruments aboard the Compton Observatory, at X-ray energies with ASCA, and at ultraviolet wavelengths with IUE. Preliminary analysis of our first CGRO Cycle 4 multiwavelength observations of PKS 0208-512 indicates a significant softening in the high-energy gamma-ray spectrum of this source, compared to earlier epochs. A possible correlation is also noted in flux variations between simultaneous ultraviolet (IUE) and X-ray (ASCA) measurements of this source. Our multiwavelength observations of PKS 0208-512 will be greatly expanded during the CGRO Cycle 5 in 1996, and our results on 0208-512 will ultimately be included in a larger survey of the gamma-ray properties of flat-spectrum radio quasars toward the region of the South Galactic Pole (see Vestrand et al., these proceedings).

Publication Source (Journal or Book title)

Astronomy and Astrophysics Supplement Series

First Page


Last Page


This document is currently not available here.