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Optical measurements during increased gamma-ray activity in 3C 454.3

ATEL # 2535; Paul S. Smith (Steward Observatory, University of Arizona), Ann E. Wehrle (Space Science Institute, Boulder, CO)
on 6 Apr 2010; 17:38 UT
Password Certification: Ann E Wehrle (

Subjects: Optical, Gamma Ray, AGN, Quasars

Observations obtained with the Steward Observatory 2.3m Bok Telescope show 3C 454.3 to be optically bright and highly linear polarized during a period of increased gamma-ray activity (ATel #2534). Differential spectrophotometry yield a V-band magnitude of 15.02 +/- 0.02 and an R-band (Kron-Cousins bandpass) magnitude of 14.53 +/- 0.01 on 2010 April 5, 12:10 UT. Spectropolarimetry of 3C 454.3 with the SPOL instrument find an average linear polarization of 9.85 +/- 0.17% at a position angle of 23.0 +/- 0.5 degrees over a 5000-7000 Angstrom spectral bin. These increased levels of optical flux and polarization are consistent with those observed during other gamma-ray active periods as observed by the Fermi Gamma-ray Space Telescope (ATel #1628; ATel #2200; ATel #2328). Ground-based optical and infrared observations are currently difficult as 3C 454.3 is at a low elevation in the sky at the start of morning twilight, but further follow-up observations are encouraged as this event has triggered a Fermi Target of Opportunity observation of 3C 454.3 (ATel #2534).

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