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Fermi-LAT detection of strong flaring activity from the FSRQ CTA 102

ATel #8722; J. Becerra (NASA/GSFC/UMD/CRESST), Bryce Carpenter (CUA/NASA/GSFC) and Sara Cutini (ASDC/INFN) on behalf of the the Fermi Large Area Telescope Collaboration
on 23 Feb 2016; 03:47 UT
Credential Certification: Josefa Becerra Gonzalez (josefa.becerra@nasa.gov)

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

Referred to by ATel #: 9869, 9924

The Large Area Telescope (LAT) on board the Fermi Gamma-ray Space Telescope has observed increasing gamma-ray activity from a source positionally consistent with the flat spectrum radio quasar CTA 102 (also known as 3FGL J2232.5+1143, Acero et al. 2015, ApJS, 218, 23) with radio coordinates R.A.: 338.1517038 deg, Dec: 11.7308067 deg (J2000, Johnston et al. 1995, AJ, 110, 880) at redshift z=1.037 (Schmidt 1965, ApJ, 141, 1295).

The source has been active in recent weeks, and bright NIR and optical flares were detected on January 14 and 28 reported in ATel #8590 and ATel #8598, respectively. On 21 February 2016, CTA 102 reached the historical maximum daily averaged flux (E>100 MeV) of (11.5+/-0.6)x10^-6 ph cm^-2 s^-1 with a photon spectral index of 1.95+/-0.04 (statistical errors only). This corresponds to a factor of ~70 increase with respect to the average flux reported in the 3FGL. The spectral index is also significantly harder compared to its 3FGL value of 2.5. The source shows intra-day variability, with the averaged gamma-ray flux over one 6-hour time bin reaching (17.38+/-1.66)x10^-6 ph cm^-2 s^-1 (~100 times the 3FGL value).

Since Fermi operates in all-sky survey mode, gamma-ray monitoring of this source will continue. A preliminary uncalibrated estimation of the daily gamma-ray flux observed by Fermi LAT is publicly available at: http://fermi.gsfc.nasa.gov/FTP/glast/data/lat/catalogs/asp/current/lightcurves/CTA102_86400.png. The Fermi LAT contact person for this source is S. Cutini (sara.cutini@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.