Optical and NIR photometry of BL Lac
ATel #6609; H. E.Jermak, R. M. Barnsley, I. A.Steele
on 22 Oct 2014; 21:35 UT
Credential Certification: Iain Steele (iainsteele@mac.com)
Subjects: Infra-Red, Optical, AGN, Blazar, Quasar, Transient
We report optical and NIR data for the blazar BL Lac, associated with the Gamma ray source 2FGLJ2202.8+4216 (z = 0.0686). NIR data were obtained during early commissioning of the new IO:I imaging camera installed on the 2.0 metre Liverpool Telescope (LT), La Palma. On 21st October 2014 (JD 2456952.47) we measure H = 10.63 +/- 0.08 calibrated with respect to 9 nearby 2MASS sources. Previous NIR photometry by Carrasco et al. (ATel #6572) on 2nd October 2014 (JD 2456932.786) reported H = 10.473 +/- 0.03 which they identified as similar to the historical maximum. We therefore suggest that the source is now declining in the NIR. We also see a decline of similar size (~0.2 magnitudes) in our optical (R band) photometric monitoring of the source over the same period using the SkyCamZ wide field camera also installed at LT.
Liverpool Telescope
