TITLE: GCN CIRCULAR NUMBER: 23855 SUBJECT: Swift Trigger 887541: MASTER inspect DATE: 19/02/04 08:31:54 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs V. Lipunov, E. Gorbovskoy, N.Tyurina, V.Kornilov, D.Vlasenko, V.Vladimirov, D.Zimnukhov, A.Kuznetsov, P.Balanutsa, A. Chasovnikov, D.Kuvshinov (Lomonosov Moscow State University, SAI, Physics Department), R. Rebolo, M. Serra, N. Lodieu, G. Israelian, L. Suarez-Andres (The Instituto de Astrofisica de Canarias), D. Buckley (South African Astronomical Observatory), V. Yurkov, A. Gabovich, Yu. Sergienko, D. Kobcev (Blagoveschensk Educational State University), A. Tlatov, V.Senik, A.V. Parhomenko, D. Dormidontov (Kislovodsk Solar Station of the Pulkovo Observatory), O. Gress, N.M. Budnev, O.Ershova, Yu.Ishmuhametova (Applied Physics Institute, Irkutsk State University), R. Podesta, C. Lopez, C.Francile, F. Podesta (Observatorio Astronomico Felix Aguilar OAFA), H.Levato (Instituto de Ciencias Astronomicas, de la Tierra y del Espacio ICATE) MASTER-SAAO robotic telescope (Global MASTER-Net http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, v.2010, 30L), located in South African Astronomical Observatory, inspected Swift Trigger 887541 error-box (Barthelmy et al. GCN23849, 21:18:17 UT; XRT_RA,Dec= 262.2442, -36.2421 +-4.7arcsec) since 2019-02-04 00:16:44UT (Lipunov et al. GCN 23851). There is no OT connected with GRB, inside Swift-XRT error-box with the following unfiltered (W=0.2B+0.8R by USNO-B1 field stars, MASTER FOV=4sq.deg.) upper limits (5sigma): Tstart Exp,s mlim 2019-02-04 00:16:44 1800 20.0 2019-02-04 00:16:44 540 18.6 2019-02-04 00:16:44 180 17.5 2019-02-04 00:35:06 180 18.4 2019-02-04 00:38:43 180 18.4 2019-02-04 01:04:45 540 19.7 2019-02-04 01:15:31 540 19.9 2019-02-04 01:30:35 1800 20.0 2019-02-04 02:23:41 540 19.8 2019-02-04 02:48:42 540 19.8 The observations started when error-box altitude was 9 deg. The sun altitude was -38deg. The message may be cited.