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Optical Photometry of the flaring gamma-ray blazar AO 0235+164

ATel #8802; Tapio Pursimo (Nordic Optical Telescope), Illa R. Losada (Nordita/Stockholm University), Matteo Messa (Stockholm University), Emanuel Gafton (Stockholm University/The Oskar Klein Centre/NOT), and Roopesh Ojha (NASA/GSFC/UMBC)
on 11 Mar 2016; 17:23 UT
Credential Certification: Roopesh Ojha (Roopesh.Ojha@gmail.com)

Subjects: Optical, Gamma Ray, >GeV, AGN, Blazar

We report optical photometry of the blazar AO 0235+164 obtained with the 2.56m Nordic Optical Telescope in La Palma to look for any enhanced optical activity associated with a recent flare in the daily averaged gamma-ray flux seen in the public lightcurve of the Fermi/LAT instrument: http://fermi.gsfc.nasa.gov/FTP/glast/data/lat/catalogs/asp/current/lightcurves/0235+164_86400.png

Fermi/LAT first reported a detection of gamma-ray activity from this source in Sep, 2008 (ATel#1744) and a short timescale flare in Oct 14, 2008 (ATel#1784). There have been recent reports of renewed gamma-ray activity (ATel#7975) and NIR flares (ATel#8044, ATel#8429).

These observations were made using the MOSCA (MOSaic CAmera) instrument. Standard iraf data reduction (de-biasing + flat field correction) was carried out and aperture photometry (iraf/apphot) was performed using differential photometry against "Star 1" (https://www.lsw.uniheidelberg.de/projects/extragalactic/charts/0235+164.html) with I=12.35±0.03 (Fiorucci M., Tosti G., Rizzi N., 1998, PASP 110, 105; Smith P.S. et al., 1985, AJ 90, 1184) yielding:
2016-03-08T20:30 I=16.32
2016-03-07T20:20 I=16.15
2016-03-06T20:15 I=16.08
2016-03-05T20:10 I=16.25

This suggests that there is no significant enhancement in its optical magnitude over its average brightness (e.g. Raiteri et al. 2008, A&A 480, 339).

Given the nature of this object and its continuing gamma-ray activity we encourage further multi-wavelength coverage. We will continue to monitor this source and report future developments using this and other platforms.