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ATEL # 1684; S.G. Djorgovski, T. Morton, A.J. Drake, A. Mahabal, E. Glikman (Caltech), P. Nugent (LBNL), C. Baltay, D. Rabinowitz (Yale), E.C. Beshore, S.M. Larson (UA/LPL), R. Williams, D. Gopal, C. Donalek, M. Graham (Caltech), A. Bauer, N. Ellman, R. Scalzo, J. Jerke (Yale), E. Christensen (Gemini Obs.)
on 28 Aug 2008; 3:44 UT
Password Certification: S. George Djorgovski (firstname.lastname@example.org)
Subjects: Optical, AGN, Quasars
We compiled archival light curves for the blazar 3C454.3, which is currently dominating the extragalactic gamma-ray sky as seen by the early GLAST/Fermi observations.
One data set is from the Palomar-Quest (PQ) survey, a combination of exposures taken in the drift scan and point-and-stare modes, supplemented by a few early observations from the JPL NEAT team. These data were obtained at Palomar 48-inch Schmidt Samuel Oschin Telescope, span a time range of about 6 years, from 04 Aug 2002 UT, through 22 June 2008 UT, and consist of 69 exposures taken on 32 separate dates. All data are in red bands, brought to an empirically determined common zero-point using nearby stars, and roughly zero-pointed using USNO-B catalog. The other data set is from the Catalina Sky Survey (CSS), obtained at the Mt. Bigellow 27-inch Schmidt telescope, with an unfiltered CCD, and consist of 86 exposures taken on 22 separate dates, from 03 July 2005 UT, through 13 June 2008 UT. No attempt is made at this point to account for the color terms, and a more detailed photometric calibrations are in progress.
The object shows a strong and often very rapid optical variability, roughly in the range ~ 13 mag to ~ 16 mag in the time interval probed here. For example, it faded by nearly a magnitude over a period of 8 days, from 03 to 11 Sep 2002 UT; it was in a relatively bright state (~ 13.2 mag) in July 2005, and faded by ~ 1.5 mag by late Sept. 2005, then brightened by about the same amount by late Oct. 2005. It was relatively faint (~ 15 mag) in Sept. - Dec. 2006. It brightened by ~ 1 mag from early July 2007 to early Aug. 2007 (to ~ 13 mag), then dropped by nearly 2 mag by early Oct. 2007 (to ~ 15 mag), and brightened again by nearly 1 mag over 11 days, from 01 to 12 Oct 2007 UT. It brightened again by ~ 1 mag from mid-Dec. 2007 to mid-Jan. 2008, then faded again by nearly 2 mag (to ~ 15.5 mag) by mud-May 2008, and brightened by ~ 1.5 mag (to ~ 14 mag) by mid-June 2008. This dramatic variability pattern may be related to its currently high gamma-ray activity.
The light curves and other information are available at http://palquest.org/blazars/
PQ and CSS blazar observations