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Detection of optical activity in the radio source B2 0619+33

ATEL # 2831; P. S. Smith (Steward Observatory, University of Arizona)
on 7 Sep 2010; 15:43 UT
Distributed as an Instant Email Notice (Request for Observations)
Password Certification: Paul S. Smith (

Subjects: Optical, >GeV, AGN
Referred to by ATEL #: 2848, 2849

In response to ATEL #2829, optical observations were obtained on September 7, 2010 for the radio source B2 0619+33 (RA: 06h22m52.221945s, Dec: +33d26m10.41027s, J2000; Kovalev et al. 2007, AJ 133, 1236) with the 1.54m Kuiper Telescope on Mt. Bigelow, Arizona using the SPOL spectropolarimeter. Comparison to two spectrophotometric standard stars yields a V magnitude of 18.48+/-0.03 for the object. This is substantially brighter than seen in the second Digitized Sky Survey (DSS2) plate, where the object is not visible. The low-resolution spectrum (R=250-450) obtained shows a featureless continuum and no redshift determination could be made. In addition to the spectrophotometry, optical linear polarization measurements were made at 10:51 UT and 11:26 UT. These respectively yield polarizations of 12.86+/-0.27% at a position angle of 103.4+/-0.6 degrees and 12.82+/-0.24% at 108.6+/-0.5 degrees.

The rapid rotation in the polarization position angle and the high level of polarization observed confirm that B2 0619+33 is a blazar. This classification is consistent with its featureless optical spectrum, strong optical variability, and the possible detection of the source by the Large Area Telescope aboard the Fermi Gamma-ray Space Telescope reported by Schinzel et al. (ATEL #2829). The optical flux and polarization activity observed in B2 0619+33 suggests that it is the counterpart to the flaring gamma-ray source. Further multi-wavelength observations are suggested to verify the connection between B2 0619+33 and the gamma-ray activity.

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