Fermi LAT Detection of a New Gamma-ray Transient near the Galactic Plane: Fermi J0431+5458
ATel #15212; I. Mereu (INFN Perugia), C. C. Cheung (NRL), on behalf of the Fermi-LAT collaboratio
on 8 Feb 2022; 01:57 UT
Credential Certification: Teddy Cheung (Teddy.Cheung@nrl.navy.mil)
Subjects: Gamma Ray, >GeV, Transient
On February 4, 2022, 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 J0431+5458. Preliminary analysis indicates the signal was significant in the single 6-hr interval from 06:00-12:00 UTC with 5-sigma significance, with a flux (E >100 MeV) of (1.0 +/- 0.4) x 10^-6 ph cm^-2 s^-1, and a photon index, Gamma = 2.1 +/- 0.3.
The best-fit location of this gamma-ray source (RA = 67.86 deg, Decl. = 54.98 deg; J2000) has a 95% containment radius of 0.26 deg (errors are statistical only). This source is located near the Galactic plane (l, b = 151.07 deg, 4.62 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 J043046+551346 (GB6 J0430+5513), with coordinates RA = 67.692125 deg, Decl. = 55.229472 deg (J2000; Condon et al. 1998, AJ, 115, 1693), and an angular distance of 0.27 deg that is formally outside of the large LAT error radius.
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 person is Isabella Mereu (mereuisabella at gmail.com).
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.
