ASAS-SN optical light-curve of blazar TXS 0506+056, located inside the IceCube-170922A error region, shows increased optical activity
ATel #10794; A. Franckowiak (DESY), K. Z. Stanek, C. S. Kochanek, T. A. Thompson (OSU), T. W.-S. Holoien, B. J. Shappee (Carnegie Observatories), J. L. Prieto (Diego Portales; MAS), Subo Dong (KIAA-PKU)
on 28 Sep 2017; 18:00 UT
Credential Certification: Krzysztof Stanek (email@example.com)
Subjects: Optical, Blazar
Archival ASAS-SN (Shappee et
al. 2014) data show an increased optical activity of the blazar TXS 0506+056, which
is located inside the error region of the high-energy neutrino
candidate IceCube-170922A, and was
found to be in a flaring state by Fermi-LAT (ATel #10791),
and it was also observed by Swift 10792).
Using ASAS-SN Sky Patrol public
all-sky light curve interface (Kochanek et
al. 2017), we retrieved
200-day light curve of TXS 0506+056, showing a rise of ~0.5 mag in
V-band over the last 50 days. Proximity to the Sun prevented
observations between April and July 2017. In earlier observations the
source was at a low state with V-band magnitude of ~14.7. V-band
magnitudes are calculated in real-time using aperture photometry, with
zero-points calibrated using the APASS catalog. ASAS-SN images have 8"
pixels (~15" FWHM PSF,) so blending/crowding might be significant in
some cases (but most likely not very significant in this case).
We also retrieved the entire
ASAS-SN light curve of TXS 0506+056, starting in October 2012, and
while it shows significant variability, the recent data are the
brightest this object has been in several years.
We thank Las Cumbres Observatory and its staff for their continued
support of ASAS-SN. ASAS-SN is funded in part by the Gordon and Betty
Moore Foundation through grant GBMF5490 to the Ohio State University,
NSF grant AST-1515927, the Mt. Cuba Astronomical Foundation, the
Center for Cosmology and AstroParticle Physics (CCAPP) at OSU, and the
Chinese Academy of Sciences South America Center for Astronomy