High optical polarization detected in blazar CGRaBS J0211+1051 from MIRO
ATel #3136; Sunil Chandra, S Ganesh, KS Baliyan, UC Joshi (Physical Research Laboratory, Ahmedabad, India)
on 31 Jan 2011; 08:53 UT
Credential Certification: Kiran S Baliyan (baliyan@prl.res.in)
Subjects: Optical, AGN, Blazar
The BL Lac object CGRaBS J0211+1051 (MG1 J021114+1051, or 1FGL J0211.2+1049, Abdo et al. 2010, ApJS,188, 405) was detected in Gamma-rays by Fermi LAT on 2011 January 23 (ATel #3120) and is known to be brightening up for last 3 years from 15.6 (2008) to 13.5 mag on Jan 24, 2011 (Atel# 3133). Swift/UVOT observations (Atel #3120, #3129) found CGRaBS J0211+1051 about 1.3 mag brighter in U band (U = 13.77+/-0.03) and 1.4 mag in W2 band (W2 = 14.44+/-0.04) on 2011 January 23, compared to the UVOT observation performed on 2010 March 5. In V band is was 14.00 mag on January 25. Gorbovskoy et al(Atel # 3134) reported discovery of 12% optical polarization in V-band on January 28, 2011. Here we report increase in optical polarization as detected on Jan 30, 2011.
We made photo-polarimetric observations on CGRaBS J0211+1051 from Mt Abu IR Observatory(MIRO), operated by the Physical Research Laboratory, Ahmedabad, during 2011 Jan 30 from UT= 14:26:33 to UT= 14:45:27 Hrs to measure optical polarization and brightness of the source in white light. We report the source to have polarization of 20.77(+/-0.412)% in white light as compared to 12% on Jan 28 (Atel # 3134). The polarization vector remained almost steady at 92.7 deg. Such as increase in polarization and brightness could be indicative of the increased activity in the jet and strengthening of magnetic field. More observations are planned tonight.