TITLE: GCN CIRCULAR NUMBER: 24479 SUBJECT: LIGO/Virgo S190510g : Xinglong-60cm upper limit of the GRAWITA REM's OT DATE: 19/05/11 10:40:06 GMT FROM: Dong Xu at NAOC/CAS Z.P. Zhu, D. Xu, B.Y. Yu, J.J. Ren, T.M. Zhang, X. Zhou, H.J. Wang, C.Z. Cui, D.W. Fan, Y.F. Xu (NAOC), X. Gao (Urumqi No.1 Senior High School), S. Yang (INAF-OAPd), H.B. Zhao, B. Li (PMO), J.Z. Liu, H.B. Niu (XAO), J.R. Mao, J.M. Bai (YNAO), report on behalf of the GWFUNC collaboration: We observed the optical transient (OT), r = 17.3 +/- 0.1 (AB, calibrated against the SDSS), in P. D'Avanzo et al. (GCN 24455) of the gravitational-wave event S190510g (GCN 24442) using the Xinglong-60cm telescope located at Xinglong, Hebei, China. The OT is ~20" away from the SDSS galaxy, SDSS J142914.95+094059.4, which has a photoZ=0.041 +/- 0.0149, corresponding to a luminosity distance of 182.2 Mpc, thus being consistent with the LIGO's luminosity distance estimate of 227 +/- 92 Mpc (GCN 24448). At the above redshift, SDSS J142914.95+094059.4 has an absolute magnitude of M(r) = 17.92-36.30 = -18.38, at the border of dwarf/normal galaxies. The OT is ~16.3 kpc away from the nucleus of the SDSS galaxy, much larger than usual radii of such galaxies. If double neutron stars are considered having been kicked out of their host galaxy earlier before, such a scenario might be possible. Under the above assumption, we obtained 15x360 s frames in R band, started at 16:12:27 on 2019-05-10, i.e., about 10 hr after the OT detected. The OT has decayed and is not detected in our stacked image of 5400 s, down to a limiting magnitude of r ~ 20.6, calibrated with the SDSS field.