Kanata optical imaging and polarimetric follow-ups for possible IceCube counterpart TXS 0506+056

ATel #10844; M. Yamanaka, Y. T. Tanaka, H. Mori, K. S. Kawabata, Y. Utsumi, T. Nakaoka, M. Kawabata., and H. Nagashima on behalf of Kanata and OISTER teams.
on 12 Oct 2017; 15:50 UT
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Credential Certification: Masayuki Yamanaka (masyamanaka@hiroshima-u.ac.jp)

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We performed the imaging observations of TXS 0506+056 (ATEL #10773, #10791, #10773, #10787, #10791, #10792, #10794, #10799, #10801, #10802, #10817, #10830, #10831, #10833, #10838, #10840) using the Hiroshima Optical and Near-InfraRed camera (HONIR; Akitaya et al. 2014, Proc. SPIE 9147, 91474) installed to the Cassegrain focus of the 1.5-m Kanata telescope at the Higashi-Hiroshima Observatory (HHO) in optical and near-infrared wavelengths on Sep 23.7, 24.8, and 25.7 (UT), just after receiving the alert of IceCube-170922A (GCN #21916). By performing relative photometry against the reference star from the the AAVSO Photometric All Sky Survey (APASS) DR9 catalog (Henden et al. 2016) detected in the same frame, the R-band magnitudes were obtained as 14.5+/-0.1, 14.7+/-0.1, and 14.6+/-0.1 mag on Sep 23.7, 24.8 and 25.7, respectively. We also obtained the simultaneous optical and near-infrared imaging polaritmetric data for TXS 0506+056 using HONIR on Sep 30.8 (UT) in the framework of the Optical and Infrared Synergetic Telescopes for Education and Research (OISTER) Target-of-opportunity observations. The total exposures in the R and Ks bands are three hours, respectively. The R-band polarization degree (P.D.) was obtained as 7.9+/-1.1%. We confirmed that the P.D. caused by the interstellar dust toward the direction of TXS 0506+056 is within 1%, indicating that the observed polarization is intrinsic. Note that the instrument polarization is estimated to be within 0.2% (Akitaya et al. 2014). Further analysis is ongoing. We will continue the polarimetric observations in optical and near-infrared wavelengths.