TITLE: GCN CIRCULAR NUMBER: 24412 SUBJECT: Fermi GRB190506.58 Global MASTER-Net observations report DATE: 19/05/07 02:46:50 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs V. Lipunov, E. Gorbovskoy, V.Kornilov, D.Kuvshinov, N.Tyurina, P.Balanutsa, A.Kuznetsov, V.V.Chazov, D. Vlasenko (Lomonosov Moscow State University, Sternberg Astronomical Institute, Moscow State University) A. Tlatov, V.Senik, A.V. Parhomenko, D. Dormidontov (Kislovodsk Solar Station of the Pulkovo Observatory) K. Ivanov, O. Gres, N.M. Budnev, S. Yazev, O. Chuvalaev, V. Poleshchuk (Irkutsk State University) V. Yurkov, A. Gabovich, Yu. Sergienko (Blagoveschensk Educational State University, Blagoveschensk) R. Podesta, Carlos Lopez and F. Podesta (Observatorio Astronomico Felix Aguilar (OAFA)) Hugo Levato and Carlos Saffe (Instituto de Ciencias Astronomicas, de la Tierra y del Espacio (ICATE)) R. Rebolo, M. Serra, N. Lodieu, G. Israelian, L. Suarez-Andres (The Instituto de Astrofisica de Canarias) D. Buckley, S. Potter, A. Kniazev, M. Kotze (South African Astronomical Observatory) MASTER-SAAO robotic telescope (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in South Africa (South African Astronomical Observatory) started inspect of the Fermi GRB190506.58 (trigger No 578843488, 12h 6m 16.08s , -68d 24m 00.00s, R=32.6) errorbox 39310 sec after trigger time at 2019-05-07 00:46:33 UT, with upper limit up to 17.2 mag. The observations began at zenit distance = 55 deg. The sun altitude is -56.6 deg. The galactic latitude b = -60 deg., longitude l = 98 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=1009391 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 39400 | 2019-05-07 00:46:33 | MASTER-SAAO | ( 8h 56m 09.60s , -59d 56m 47.72s) | C | 180 | 17.2 | 39711 | 2019-05-07 00:51:43 | MASTER-SAAO | ( 8h 56m 01.66s , -57d 57m 03.01s) | C | 180 | 15.8 | 40082 | 2019-05-07 00:57:54 | MASTER-SAAO | ( 8h 56m 06.92s , -59d 56m 43.86s) | C | 180 | 16.7 | 40298 | 2019-05-07 01:01:30 | MASTER-SAAO | ( 9h 12m 06.70s , -59d 56m 46.86s) | C | 180 | 17.0 | 40576 | 2019-05-07 01:06:08 | MASTER-SAAO | ( 8h 55m 59.72s , -57d 56m 37.35s) | C | 180 | 15.3 | 40793 | 2019-05-07 01:09:45 | MASTER-SAAO | ( 9h 11m 05.21s , -57d 56m 43.09s) | C | 180 | 14.1 | 41131 | 2019-05-07 01:15:23 | MASTER-SAAO | ( 9h 12m 05.68s , -59d 56m 44.03s) | C | 180 | 17.0 | 41409 | 2019-05-07 01:20:01 | MASTER-SAAO | ( 9h 11m 05.06s , -57d 56m 39.51s) | C | 180 | 17.2 | Filter C is a clear (unfiltred) band. The observation and reduction will continue. The message may be cited.