Alert Notice 411: Request for observations of the blazar 3C 66A

October 31, 2009: Further to AAVSO Alert Notice 353 (aavso-alert-notice-353) (July 11, 2007), Dr. Markus Boettcher (Ohio University) requests optical observations of the blazar 3C 66A during its current high state. Optical observations will support gamma-ray observations by the VERITAS telescope in Arizona. All observations, including visual estimates and CCD photometry are encouraged. 3C 66A has been brighter than average for several weeks, and is now above the optical threshold of m(vis) ~ 14.1 for pursuing intensive optical coverage. Recent CCD and visual observations suggest a brightening trend over past two weeks: JD 2455121.7698 (2009 Oct 17.2698), m(V)=14.25 (E. Erdelyi, Carlsbad, CA, USA); 2455123.4201 (Oct 18.9201), m(vis)=14.2 (K. Wenzel, Grossostheim, Ger.); 2455125.4375 (Oct 20.9375), m(vis)=14.1 (Wenzel); 2455127.3750 (Oct 22.8750), m(vis)=14.0 (Wenzel); 2455129.6993 (Oct 25.1993), m(vis)=13.7 (M. Simonsen, Imlay City, Michigan, USA); 2455135.3958 (Oct 30.8958), m(vis)=13.8 (Wenzel).<
CCD observers are asked to obtain high S/N observations with filters if possible; use an Rc if available for time series, and alternate with a B or V filter if also available. High signal to noise is preferred over faster observing cadence. One set of BVRcIc per night would also be very useful.
3C 66A is located at the following (J2000) coordinates: RA: 02:22:39.61 , Dec: +43:02:07.8
Charts for 3C 66A may be plotted using AAVSO VSP:
Please submit all observations to the AAVSO International Database using the name "3C 66A".
For more information on blazars and the AAVSO High Energy Network, please visit
This AAVSO Alert Notice was prepared by Dr. Matthew Templeton.


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