3EG J2016 + 3657: Confirming an EGRET blazar behind the Galactic plane

J. P. Halpern, M. Eracleous, R. Mukherjee, E. V. Gotthelf

Research output: Contribution to journalArticlepeer-review

29 Scopus citations


We recently identified the blazar-like radio source G74.87 + 1.22 (B2013 + 370) as the counterpart of the high-energy γ-ray source 3EG J2016 + 3657 in the Galactic plane. However, since most blazar identifications of EGRET sources are only probabilistic in quality even at high Galactic latitude, and since there also exists a population of unidentified Galactic EGRET sources, we sought to obtain additional evidence to support our assertion that 3EG J2016 + 3657 is a blazar. These new observations consist of a complete set of classifications for the 14 brightest ROSAT X-ray sources in the error circle, of which B2013 + 370 remains the most likely source of the γ-rays. We also obtained further optical photometry of B2013 + 370 itself which shows that it is variable, providing additional evidence of its blazar nature. Interestingly, this field contains, in addition to the blazar, the Crab-like supernova remnant CTB 87, which is too distant to be the EGRET source, and three newly discovered cataclysmic variables, all five of these X-ray sources falling within 16′ of each other. This illustrates the daunting problem of obtaining complete identifications of EGRET sources in the Galactic plane.

Original languageEnglish (US)
Pages (from-to)1016-1023
Number of pages8
JournalAstrophysical Journal
Issue number2 PART 1
StatePublished - Apr 20 2001

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science


Dive into the research topics of '3EG J2016 + 3657: Confirming an EGRET blazar behind the Galactic plane'. Together they form a unique fingerprint.

Cite this