[ Previous | Next | ADS ]

Fermi LAT detection of a continuing increase of gamma-ray activity of CTA 102

ATel #4409; M. Orienti (Univ. Bologna, INAF-IRA Bologna), F. D'Ammando (Univ. Perugia, INFN) on behalf of the Fermi Large Area Telescope Collaboration
on 21 Sep 2012; 20:03 UT
Credential Certification: Filippo D'Ammando (filippo.dammando@fisica.unipg.it)

Subjects: Gamma Ray, >GeV, AGN, Blazar, Quasar

Referred to by ATel #: 6631, 8478, 9869, 9924, 10292

The Large Area Telescope (LAT), on board the Fermi Gamma-ray Space Telescope, has observed gamma-ray flaring activity from a source positionally consistent with the flat spectrum radio quasar CTA 102 (also known as 2FGL J2232.4+1143, Nolan et al. 2012, ApJS, 199, 31) with radio coordinates R.A.: 338.1517038 deg, Dec: 11.7308067 deg (J2000, Johnston et al. 1995, AJ, 110, 880) at redshift z=1.037 (Schmidt 1965, ApJ, 141, 1295).

Following an unprecedented optical outburst and increased gamma-ray flux on 18 September (ATel #4397), preliminary results indicate that CTA 102 reached a daily gamma-ray flux (E > 100 MeV) of (2.7+/-0.4) x10^-6 ph cm^-2 s^-1 (errors are statistical only) on 19 September, with a peak flux of (5.2+/-1.0) x10^-6 ph cm^-2 s^1 between 0:00 UT and 06:00 UT. The observed daily flux is about a factor of 30 greater than the average flux reported in the second Fermi LAT catalog (2FGL, Nolan et al. 2012, ApJS, 199, 31). A previous gamma-ray flare from this source was detected in May 2011 by Fermi LAT (ATel #3320).

Because Fermi operates in an all-sky scanning mode, regular gamma-ray monitoring of this source will continue. In consideration of the ongoing activity of this source we encourage multiwavelength observations. For this source the Fermi LAT contact person is S. Cutini (sara.cutini@asdc.asi.it).

The Fermi LAT is a pair conversion telescope designed to cover the energy band from 20 MeV to greater than 300 GeV. It is the product of an international collaboration between NASA and DOE in the U.S. and many scientific institutions across France, Italy, Japan and Sweden.