High-activity state of the blazar AO 0235+164

ATel #16253; Boyko Mihov (Institute of Astronomy and NAO, Bulgarian Academy of Sciences), Lyuba Slavcheva-Mihova (Institute of Astronomy and NAO, Bulgarian Academy of Sciences)
on 24 Sep 2023; 12:49 UT
Credential Certification: Boyko Mihov (bmihov@astro.bas.bg)

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The blazar AO 0235+164 was recently reported in a flaring state (ATel #16190, ATel #16199, ATel #16204, TNSAN 2023-245). We performed BVRI photometric observations of the blazar in August and September 2023 using the 2-m telescope of the Rozhen National Astronomical Observatory, Bulgaria. The telescope was equipped with a two-channel focal reducer FoReRo-2, Andor iKon-L CCD cameras (attached at the blue and red channels of the reducer), and a set of Johnson-Cousins BVRI filters. In each observing run multiple frames were obtained in each band.

The instrumental magnitudes of the objects of interest were derived using 2 arcsec radius aperture photometry. The calibration was performed using the reference stars 3, 8, 9, and 11 from the standard sequence of González-Pérez et al. (2001, AJ, 122, 2055). Here we report our R band photometry:

UT	JD	mag R	err R	N
Aug 17.0901	2460173.590069	17.147	0.029	9
Aug 18.0937	2460174.593675	17.239	0.025	4
Sep 10.1071	2460197.607106	16.978	0.009	5
Sep 12.1052	2460199.605156	16.048	0.022	6
Sep 13.1100	2460200.610046	16.512	0.017	13

The reported magnitudes are a weighted average over the N frames got during the night, and the quoted uncertainties are the larger between the standard error of the weighted mean and the standard deviation about the weighted mean.

Our observations detect a variability amplitude of about 1.2 mag within a month. This confirms the current high activity of AO 0235+164 in the optical and indicates the need of a further multi-wavelength observations of the blazar.