Near-infrared observations of GRS 1915+105 in an unusual state with Kanata telescope
ATel #12765; F. Imazato, M. Sasada, T. Nakaoka, K. Takagi (Hiroshima University)
on 16 May 2019; 04:06 UT
Credential Certification: Makoto Uemura (uemuram@hiroshima-u.ac.jp)
Subjects: Infra-Red, Black Hole, Transient
Recently, a black hole X-ray binary GRS 1915+105 has been in a very low luminosity state and dimming at X-ray wavelength (ATel: #11828, #12742, #12743, and #12755). Iwakiri et al. (ATel #12761), however, reported that the X-ray flux of this source is rebrightening on 14th May 2019 by MAXI/GSC.
We have performed the near-infrared observations of the source since MJD 58579.76 (6th April 2019) using the Hiroshima Optical and Near-InfraRed camera (HONIR; Akitaya et al. 2014, Proc. SPIE 9147, 91474O) installed to the Cassegrain focus of 1.5-m Kanata telescope at the Higashi-Hiroshima Observatory. Our near-infrared light curve shows that the source was Ks ~ 15.59+/-0.03 mag at 6th April 2019, which is fainter than the reported faintest magnitude of Ks ~ 13.6 mag in the soft state (Arai et al. 2009), and has been brightened at 12th May 2019 (Ks ~ 14.77+/-0.02 mag). We will continue the near-infrared observations of GRS 1915+105.
Ks-band light curve of GRS 1915+105