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Optical Activity of the Flaring Gamma-ray Blazar TXS 1100+122

ATel #5221; Sonia Tamburri (INAF-OABr), Benjamin Hendricks (LSW Heidelberg), Marijana Smailagic (Belgrade University), Jaan Laur (Tartu Observatory), Tapio Pursimo (Nordic Optical Telescope) and Roopesh Ojha (ORAU/NASA/GSFC)
on 22 Jul 2013; 23:09 UT
Credential Certification: Roopesh Ojha (Roopesh.Ojha@gmail.com)

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

Referred to by ATel #: 6914

We report optical photometry of the high redshift (z=0.9139; Hewett, P. C. & Wild, V. 2010, MNRAS, 405, 2302) flat spectrum radio quasar TXS 1100+122 obtained with the 2.56m Nordic Optical Telescope in La Palma. Observations were made with the R-filter on July 20. The photometry was calibrated against five nearby field stars using SDSS r-magnitudes (converted to R-band) as reference. The result was:
R=17.9

As a comparison the survey magnitudes of this object are:
USNO-A2 R=18.4 epoch 1954.11
USNO-B2 R1=18.61 R2=18.78 mean epoch 1976.1
GSC2.3 F=18.25 epoch 1989.9
SDSS r=18.410, 18.703 2002.9528 & 2003.2 (converted to R: 18.27 & 18.56 respectively)
These survey magnitudes were obtained using the CDS/Aladin tool.

These observations were made in response to the detection of a gamma-ray flare with a particularly hard gamma-ray spectrum by the Fermi LAT on July 8th, 2013 (Atel#5202). Our observations find TXS 1100+122 to be brighter than it has ever been observed to be and half a magnitude brighter than its median brightness. This supports the identification of TXS 1100+122 as the gamma-ray flaring source detected by Fermi LAT.

Further multi-wavelength observations of this source are encouraged. We will continue to monitor this source and report future developments using this and other platforms.