TITLE: GCN CIRCULAR NUMBER: 24219 SUBJECT: LIGO/Virgo S190425z : IRSF/SIRIUS NIR photometry of ZTF19aarykkb and ZTF19aarzaod DATE: 19/04/26 11:27:51 GMT FROM: Kumiko Morihana at Nagoya University K. Morihana (Nagoya Univ.), M. Jian (Univ. of Tokyo), T. Nagayama (Kagoshima Univ.) report on behalf of J-GEM collaboration: We observed ZTF19aarykkb and ZTF19aarzaod reported by the Zwicky Transient Facility (Kasliwal et al., GCN 24191) with the near-infrared (J, H, Ks) simultaneous imaging camera SIRIUS attached to 1.4 m telescope IRSF (InfraRed Survey Facility) in Sutherland observatory, South Africa. The observation started on 2019-04-26 00:19:13 UT. The exposure times in J-, H-, Ks-bands are ~30min (ZTF19aarykkb) and ~40 min (ZTF19aarzaod), respectively. We performed aperture photometry and the magnitude are listed below. The photometric magnitudes may have an effect from the host galaxy and nearest stars. Target UTC J (err) H (err) Ks (err) --------------------------------------------------------------------------------------------------- ZTF19aarykkb 2019-04-26 00:36:51.7 16.8 (0.1) 16.4 (0.1) 16.1 (0.1) ZTF19aarzaod 2019-04-26 01:25:52.9 17.4 (0.1) 16.7 (0.1) 16.4 (0.1) --------------------------------------------------------------------------------------------------- Given magnitudes were calibrated against 2MASS point sources (Vega System) in the field.