TITLE: GCN CIRCULAR NUMBER: 24493 SUBJECT: LIGO/Virgo S190510g: KMTNet observation of DECam-GROWTH and DESGW candidates DATE: 19/05/11 23:37:09 GMT FROM: Myungshin Im at Seoul Nat U Myungshin Im (SNU), Joonho Kim (SNU), Chung-Uk Lee (KASI), Seung-Lee Kim (KASI), Gregory S. H. Paek (SNU), Gu Lim (SNU), Changsu Choi (SNU), Sungyong Hwang (SNU), Bomi Park (SNU), Sophia Kim (SNU), Hyung Mok Lee (KASI), on behalf of a larger collaboration With KMTNet, we observed the optical counterpart candidates from DECam-GROWTH and DESGW (Andreoni et al. GCN 24467; Annis et al. GCN 24474; Sores-Santos et al. GCN 24480) of the BNS merger candidate event, S190510g (LIGO/Virgo GCN 24448). The observation took place at the KMTNet South Africa (SAAO), Chile (CTIO), and Australia (SSO) stations. The list of the observed targets are given below, along with preliminary R-band magnitudes. Note that the errors do not include systematic errors due to image subtraction. The error associated with the image subtraction should be considered to be 0.1-0.2 mag at this moment. None of the candidates below show significant fading (> 0.5 mag) over ~1 day. All of the candidates show very slow or no fading, consistent with them being supernovae. Further observation is ongoing. We thank the KMTNet staffs for performing the observation. Object name UT R(mag) Rerr desgw-190510a 2019-05-11T17:33:16 21.26 0.07 DG19bexl 2019-05-10T17:54:47 21.21 0.04 2019-05-11T16:57:13 21.49 0.09 DG19etsk 2019-05-10T17:33:32 20.92 0.10 DG19fqqk 2019-05-10T18:08:23 20.57 0.04 (desgw-190510c) 2019-05-10T23:45:52 20.88 0.04 2019-05-11T17:36:25 20.71 0.04 DG19lcnl 2019-05-10T23:33:34 19.92 0.04 2019-05-11T17:23:49 19.82 0.03 DG19llhk 2019-05-10T17:08:10 21.23 0.04 2019-05-10T17:20:36 21.17 0.05 2019-05-11T17:20:40 21.37 0.11 DG19nanl 2019-05-10T23:33:34 20.43 0.04 DG19nouo 2019-05-10T17:20:36 21.64 0.05 2019-05-10T23:21:17 21.51 0.05 DG19oahn 2019-05-11T16:50:54 19.48 0.03 DG19ootl 2019-05-10T23:33:34 21.51 0.07 DG19ukvo 2019-05-10T16:48:24 21.56 0.14 DG19yhhm 2019-05-10T17:20:36 20.43 0.04 2019-05-10T23:21:17 20.33 0.05 DG19zaxn 2019-05-10T17:27:13 21.16 0.04