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Optical flare observed in the flaring gamma-ray blazar CGRaBS J0809+5341 (87GB 080551.6+535010)

ATel #10916; Tapio Pursimo (NOT), F. J. Galindo-Guil (NOT), Pere Blay Serrano (NOT), and Roopesh Ojha (NASA/GSFC/UMBC)
on 1 Nov 2017; 01:13 UT
Credential Certification: Roopesh Ojha (Roopesh.Ojha@gmail.com)

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

We report optical photometry of the blazar CGRaBS J0809+5341 (87GB 080551.6+535010), obtained with the 2.56m Nordic Optical Telescope in La Palma, to look for any enhanced optical activity associated with a recent flare in the daily averaged gamma-ray flux (ATel#10905).

These NOT observations were made using the ALFOSC (Andalucia Faint Object Spectrograph and Camera) instrument at the epoch 2017-10-30T04:53. Standard IRAF data reduction (de-biasing + flat field correction with twilight flats) was carried out and differential photometry was performed. The brightness was estimated against five SDSSr stars between 15.3 and 17.4 magnitude. The std-dev of the zero point was 0.02 mag.

We find that CGRaBS J0809+5341 had an SDSS r-magnitude = 17.88+/-0.02 (AB-system). This result suggests that there is significant enhancement in its optical magnitude. For example, historic values of this object's r-magnitude at epochs 2003.8859 and 2003.8123 are 20.381+-0.031 and 19.711+-0.018, respectively (Aladin/SDSS-DR9).

This object was previously reported to be flaring in the optical (ATel#6070, ATel#6096, ATel#6127) and NIR (ATel#6136) in April/May 2014. We encourage further multi-wavelength coverage. We will continue to monitor this source and report future developments using this and other platforms.