Fermi LAT detection of a GeV flare from the FSRQ SDSS J002829.81+200026.7
ATel #12084; S. Buson (Univ. of Wuerzburg), R. Angioni (MPIfR-Bonn), V. Paliya (Clemson Univ.) on behalf of the Fermi Large Area Telescope Collaboration
on 7 Oct 2018; 20:58 UT
Credential Certification: Sara Buson (sara.buson@gmail.com)
Subjects: Gamma Ray, >GeV, Request for Observations, AGN, Blazar
The Large Area Telescope (LAT) on board the Fermi Gamma-ray Space Telescope has observed an increasing gamma-ray flux from a source positionally coincident with SDSS J002829.81+200026.7 at RA: 00h 28m 29.8s, Dec. +20d 00m 27s (J2000); (Beasley et al. 2002 ApJS, 141, 13B). This is a flat spectrum radio quasar also known as TXS 0025+197 (Douglas et al. 1996 AJ, 111.1945D), at redshift of 1.552007 (Alam et al. 2015, ApJS, 219, 12).
Preliminary analysis indicates that the source was in a high state between October 3-5, 2018. On October 4 the source reached a peak gamma-ray flux (E>100 MeV) of (0.6 +/- 0.1) x 10^-6 ph/cm^2/s (statistical uncertainty only). This represents an increase by a factor of 50 over the average flux reported in the third Fermi-LAT catalog (3FGL J0028.8+1951, Acero et al. 2015, ApJS, 218, 23). The enhanced state was characterized by a hard spectrum, with average photon index of 1.7 +/- 0.1, significantly harder than the 3FGL average index of 2.4 +/- 0.1. During the flare the LAT detected some high-energy (>10 GeV) photons positionally consistent with this source.
The source was in an optical high state during these dates as reported by ASAS-SN (Stanek et al. ATel #12082).
Since Fermi normally operates in an all-sky scanning mode, regular monitoring of this source will continue. In consideration of the ongoing activity of this source we strongly encourage multiwavelength observations. The Fermi LAT contact persons are S. Buson (sara.buson at gmail.com) and R. Angioni (angioni at mpifr-bonn.mpg.de).
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.
