Fermi LAT Detection of a New Gamma-ray Transient in the Galactic Plane: Fermi J2101+5806
ATel #13918; S. Buson (Univ. of Wuerzburg), S. Ciprini (SSDC/INFN), R. Angioni (SSDC/INFN), C. C. Cheung (NRL), on behalf of the Fermi-LAT collaboration
on 6 Aug 2020; 08:57 UT
Credential Certification: Sara Buson (sara.buson@gmail.com)
Subjects: Gamma Ray, >GeV, Request for Observations, AGN, Blazar
On Aug 4, 2020, the Large Area Telescope (LAT), one of the two instruments on the Fermi Gamma-ray Space Telescope, observed gamma-ray emission from a new transient source, Fermi J2101+5806. Preliminary analysis indicates the signal was dominant in the last 6-hr interval (18:00-24:00 UTC) with TS = 28 (corresponding to ~4 sigma formal significance), a flux (E >100 MeV) of (6.7 +/- 2.6) x 10^-7 ph cm^-2 s^-1, and a photon index, Gamma = 1.8 +/- 0.2.
The best-fit location of this gamma-ray source (RA = 315.37 deg, Decl. = 58.11 deg; J2000) has a 95% containment radius of 0.36 deg (errors are statistical only). This source is located near the Galactic plane (l, b = 96.2 deg, 7.7 deg), and is not in any published LAT catalog and in the past has not been detected by AGILE or EGRET. The closest candidate counterpart is the flat-spectrum radio source NVSS J210137+575858 (Massaro et al. 2014, ApJS, 231, 3), with coordinates RA = 315.40417 deg, Decl. = 57.98286 deg (J2000; Condon et al. 1998, AJ, 115, 1693), at an angular distance of 0.13 deg.
Because Fermi normally operates in an all-sky scanning mode, regular gamma-ray monitoring of this source will continue. We encourage multifrequency observations of this source. For this source, the Fermi-LAT contact persons are Sara Buson (sara.buson at gmail.com) and Stefano Ciprini (stefano.ciprini at ssdc.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.
