Yoshida, M., Tanaka, M., Terai, T., Nakata, F., Furusawa, H.,
Koshida, S. (NAOJ), Utsumi, Y., Kawabata K. S. (Hiroshima Univ.),
Tominaga, N. (Konan Univ.), Motohara, K., Ohsawa, R., Morokuma, T.,
Yasuda, N. (Univ. of Tokyo), Kawai, N. (Tokyo Tech) on behalf of
the J-GEM collaboration
As reported in Yoshida et al. 2017 (GCN 21549), we performed z-band imaging
observations for the gravitational wave event G298048 (GCN 21505; 21509; 21513)
with Hyper Suprime-Cam attached to the Subaru telescope on August 18 2017 UT.
The survey fields include SSS17a (RA = 13:09:48.09 DECL. = -23:22:53.35,
Coulter et al. 2017; GCN 21529) possibly associated with G298048. After photometric
calibration with Pan-STARRS1 catalog (Chambers et al. 2016) using HSC
pipeline (Bosch et al. 2017), we obtained psf magnitude of z = 17.3, which
is consistent with the magnitudes reported by Chambers et al. (GCN 21553).
We did not find a significant variability with > 0.1 mag during
our observations from 5:16 UT until 5:40 UT.