[ Previous | Next | ADS ]

Fermi LAT detection of increased gamma-ray activity from MG1 J123931+0443 and GB6 J0742+5444

ATel #3445; D. Gasparrini (ASI Science Data Center/INAF) on behalf of the Fermi Large Area Telescope Collaboration
on 21 Jun 2011; 18:40 UT
Credential Certification: Dario Gasparrini (dario.gasparrini@asdc.asi.it)

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

The Large Area Telescope (LAT) on board the Fermi Gamma-ray Space Telescope has observed an increasing gamma-ray flux from sources positionally consistent with MG1 J123931+0443 (also known as GB6 J1239+0443, CRATES J1239+0443, SDSS J123932.75+044305.3) and GB6 J0742+5444 (also known as 87GB 073840.5+545138, BZU J0742+5444).

MG1 J123931+0443 (RA:12h39m32.7556s Dec +04d43m05.233s, J2000, A. J. Beasley et al. 2002, ApJS, 141, 13) is a FSRQ with z=1.762090 (SDDS Data Release 2) associated with 1FGL J1239.5+0443 (A. Abdo et al. 2010 ApJ,715,429) while GB6 J0742+5444 (RA: 07h42m39.8s, Dec: +54d44m25s, J2000, A. J. Beasley et al. 2002, ApJS, 141, 13) is a FSRQ with z=0.72 (J. Halpern et al. 2003, AJ, 125, 572) associated with 1FGL J0742.2+5443 (A. Abdo et al. 2010 ApJ,715,429).

Preliminary analysis indicates that MG1 J123931+0443 on June 19, 2011, was in a high state with a daily gamma-ray flux (E > 100MeV) of (1.1+/-0.3)x10^-6 photons/cm^2/s (errors are statistical only), which represents an increase of a factor of about 13 with respect to the average source flux observed in the first eleven months of Fermi observations (A. Abdo et al. 2010, ApJS, 188, 405). Previous gamma-ray flaring activity of this source was reported in ATel #1888 by the Fermi-LAT Team.

Preliminary analysis indicates that GB6 J0742+5444 on June 19, 2011, was in a high state with a daily gamma-ray flux (E > 100MeV) of (1.0+/-0.2)x10^-6 photons/cm^2/s (errors are statistical only), which represents an increase of a factor of about 8 with respect to the average source flux observed in the first eleven months of Fermi observations (A. Abdo et al. 2010, ApJS, 188, 405). The Fermi-LAT team already reported a gamma ray flare from this source in ATel #3196.

Both sources are LAT Monitored Sources, and consequently a preliminary estimation of the daily gamma-ray flux observed by Fermi LAT is publicly available (link: http://fermi.gsfc.nasa.gov/ssc/data/access/lat/msl_lc/ ).

Because Fermi operates in an all-sky scanning mode, regular gamma-ray monitoring of these sources will continue. In consideration of the ongoing activity of these two sources we encourage multi-wavelength observations. For MG1 J123931+0443 the Fermi LAT contact persons are Andrea Tramacere (tramacer@slac.stanford.edu) and Nanda Rea (N.Rea@uva.nl), for GB6 J0742+5444 the Fermi LAT contact person is Davide Donato (donato@milkyway.gsfc.nasa.gov).

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.