Fermi-LAT detection of a GeV flare from the BL Lac object 1ES 2322-409
ATel #5457; Stefano Ciprini (ASI Science Data Center and INAF Observatory of Rome, Italy), on behalf of the Fermi Large Area Telescope Collaboration
on 9 Oct 2013; 10:09 UT
Credential Certification: Stefano Ciprini (stefano.ciprini@asdc.asi.it)
Subjects: Gamma Ray, >GeV, VHE, Request for Observations, Blazar, Quasar
The Large Area Telescope (LAT), one of the two instruments on the Fermi Gamma-ray Space Telescope, has observed an increasing gamma-ray flux from a source positionally consistent with the
BL Lac object 1ES 2322-409 (also know as 2FGL J2324.7-4042, Nolan et al. 2012, ApJS, 199, 31, and as 1FHL J2324.6-4041, Ackermann et al., ApJS, submitted, arXiv:1306.6772), with 2MASS counterpart coordinates, (J2000.0), R.A.: 351.18612 deg, Dec: -40.68036 deg (Mao 2011, New Ast., 16, 503). This high-energy synchrotron peak blazar has redshift z=0.17359 (Jones et al. 2009, MNRAS, 399, 683, 6dF Galaxy Survey DR3).
Preliminary analysis indicates that 1ES 2322-409 on October 7, 2013 was in a high state with a daily averaged gamma-ray flux (E>100MeV) of (0.8 +/- 0.2) x 10^-6 photons cm^-2 s^-1 (statistical uncertainty only), about 75 times greater than the average flux reported in the second Fermi-LAT catalog (2FGL), and a daily photon index of 2.0+/-0.2. In a 6-hour interval of October 8, the source was detected at a flux level of (1.7+/-0.4) x 10^-6 photons cm^-2 s^-1 (statistical uncertainty only). This high energy peaked, optically bright (R magnitude is 15.7) BL Lac object, also a member of the 1FHL catalog of LAT sources detected above 10 GeV, can be of interest for detection searches by Cherenkov telescopes.
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. Ciprini(stefano.ciprini@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.