TITLE: GCN CIRCULAR NUMBER: 21587 SUBJECT: LIGO/Virgo G298048: MASTER photometry of the SSS17a in NGC 4993 DATE: 17/08/19 08:10:30 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs V.M.Lipunov, E. Gorbovskoy, V.G.Kornilov, N.Tyurina, V.Shumkov, D.Kuvshinov, P.Balanutsa, O.Gress, A.Kuznetsov, M.I.Panchenko, A.V.Krylov, I.Gorbunov Lomonosov Moscow State University, Sternberg Astronomical Institute D.Buckley, S.Potter, M.Kotze, South African Astronomical Observatory R.Podesta, C.Lopez, F.Podesta Observatorio Astronomico Felix Aguilar (OAFA) , National University of San Juan, Argentina H.Levato, C.Saffe Instituto de Ciencias Astronomicas,de la Tierra y del Espacio (ICATE), San Juan, Argentina N.M. Budnev, O. Gress, K. Ivanov, S.Yazev Irkutsk State University V.Yurkov, Yu.Sergienko, A.Gabovich Blagoveschensk Educational State University, Blagoveschensk R. Rebolo, M. Serra-Ricart, G. Israelian, N.Lodiu The Instituto de Astrofisica de Canarias A. Tlatov, V.Sennik Kislovodsk Solar Station of the Pulkovo Observatory As we reported in LVC GCN 21546 MASTER-OAFA have imaged the BAYESTAR localization map of LIGO/Virgo G298048 (GCN 21513). MASTER-SAAO have new images of NGC 4993 galaxy starting 2017-08-18 17:06:55 UT in B, R and unfiletred with magnitude limit 19.8 (Lipunov et al., LVC GCN 21570). We see object in B, R and unfiltered images detected by Coulter et al. (LVC GCN 21529), Allam et al. (LVC GCN 21530), Yang et al. (LVC GCN 21531), Melandri et al. (LVC GCN 21532), Lipunov et al., (LVC GCN 21546). B = 18.5 +- 0.2 R = 17.5 +- 0.2 W = 18.0 +- 0.2 The unfiltered magnitude not changed with respect to first observations (Lipunov et al., LVC GCN 21546) This message can be citted.