Optical and Gamma-ray Flare from spectrally hard FSRQ TXS 1100+122

ATel #6914; Tapio Pursimo (NOT), and Roopesh Ojha (NASA/GSFC/ORAU), Daniel Kocevski (GSFC/NASA) on behalf of the Fermi Large Area Telescope Collaboration
on 14 Jan 2015; 02:01 UT
Credential Certification: Roopesh Ojha (Roopesh.Ojha@gmail.com)

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The Large Area Telescope (LAT), one of the two instruments on the Fermi Gamma-ray Space Telescope, has observed increasing gamma-ray flux from a source positionally consistent with the flat spectrum radio quasar (FSRQ) TXS 1100+122 (also known as SDSS J110303.52+115816.5), which has z=0.913941 (Hewett & Wild, 2010, MNRAS, 405, 2302). It is associated with 3FGL J1103.1+1155 (http://arxiv.org/abs/1501.02003), a source not previously reported in any gamma-ray catalog.

Preliminary analysis indicates that on Jan 1 and Jan 4, 2015, the daily averaged flux (E>100MeV) was (0.3 +/- 0.1) x 10^-6 and (0.6 +/- 0.2) x 10^-6 photons cm^-2 s^-1, respectively. The photon index was 1.90 +/- 0.23 and 2.07 +/- 0.24, respectively (errors are statistical only). This source last flared in July 2013 (ATel#5202) when it also displayed an unusually hard photon index. The source was also detected using a new method implemented within the Fermi-LAT Collaboration known as 'Fermi All-sky Variability Analysis' that searches the sky for high-energy transients on weekly time scales (Ackermann et al. 2013, ApJ, 771, 57).

Optical photometry of TXS 1100+122 was obtained with the 2.56m Nordic Optical Telescope in La Palma using the the R-filter. Analysis of photometry data used iraf/apphot. Zero point correction was made using field SDSS magnitudes converted from SDSS r to R using the Jordi equations (https://www.sdss3.org/dr10/algorithms/sdssUBVRITransform.php). The error reported is the zero point estimate using 6 to 7 field stars after sigma clipping. Using 8 or 5 pixel radius aperture changed the final magnitude by 0.01 or less.

On Jan 5, Jan 7, and Jan 12, 2015, the magnitudes were (16.081 +/- 0.022), (16.446 +/- 0.016), and (16.389 +/- 0.022), respectively. This is almost two magnitudes brighter than the R-band magnitude observed during its last gamma-ray high state in July 2013 (see ATel#5221).

Because Fermi operates in an all-sky scanning mode, regular gamma-ray monitoring of this source will continue. Multiwavelength observations during the ongoing activity of this source are strongly encouraged. The Fermi LAT contact person is Roopesh Ojha (e-mail:Roopesh.Ojha@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.