{
  "eventId": "GRB 260303B",
  "bibcode": "2026GCN.43912....1L",
  "body": "V.Lipunov, E.Gorbovskoy, A.Kuznetsov, K.Zhirkov, I.Panchenko, N.Tiurina, P.Balanutsa, V.Topolev, D.Vlasenko, \nG.Antipov,  A.Sankovich, Yu.Tselik, Ya.Kechin, V.Senik, A.Chasovnikov, K.Labsina, I. Gorbunov (Lomonosov MSU),\nO.Gress, N.Budnev (ISU),\nC.Francile,  F. Podesta, R.Podesta, E. Gonzalez  (Observatorio Astronomico Felix Aguilar (OAFA),\nA. Tlatov, D. Dormidontov (Kislovodsk Solar Station of the Pulkovo Observatory),\nA.Sosnovskij (CrAO),\nA. Gabovich, V.Yurkov (Blagoveschensk Educational StateUniversity),\nD.Buckley (SAAO),\nR.Rebolo (The Instituto de Astrofisica de Canarias),\nL.Carrasco, J.R.Valdes, V.Chavushyan, V.M.Patino Alvarez, J.Martinez,\nA.R.Corella, L.H.Rodriguez (INAOE, Guillermo Haro Astrophysics Observatory) \n\nMASTER-SAAO robotic telescope  [1]  located in South Africa (South African Astronomical Observatory) started inspect of the Fermi GRB 260303B ( Fermi GBM team, GCN 43907) errorbox  20103 sec after notice time and 20130 sec after trigger time at 2026-03-03 18:59:50 UT, with upper limit up to  16.5 mag. The observations began at zenith distance = 82 deg. The sun  altitude  is -22.8 deg. \n\nThe galactic latitude b = -87 deg., longitude l = 48 deg.\n\n\nReal time updated cover map and OT discovered available here: \nhttps://master.sai.msu.ru/site/master2/observ.php?id=3166705\n\nWe obtain a following upper limits.  \n\nTmid-T0  |      Date Time      |          Site       |             Coord (J2000)          |Filt.| Expt. | Limit| Comment\n_________|_____________________|_____________________|____________________________________|_____|_______|_______|________\n\n   20160 | 2026-03-03 18:59:50 |         MASTER-SAAO | (00h 37m 01.21s , -26d 50m 03.0s) |   C |    60 | 16.2 |        \n   20252 | 2026-03-03 19:01:22 |         MASTER-SAAO | (00h 37m 03.97s , -26d 48m 23.8s) |   C |    60 | 16.5 |        \n   20344 | 2026-03-03 19:02:54 |         MASTER-SAAO | (00h 36m 56.33s , -26d 49m 08.6s) |   C |    60 | 16.4 |        \n   20466 | 2026-03-03 19:04:26 |         MASTER-SAAO | (00h 36m 55.39s , -26d 48m 01.6s) |   C |   120 | 15.8 |        \nFilter C is a clear (unfiltred) band. \n\n\nThe observation and reduction will continue. \nThe message may be cited.\n\n[1] - V.M. Lipunov, V.G. Kornilov, E.S. Gorbovskoy, N.A. Tiurina & A.S.Kuznetsov, 2023,  Astronomical Robotic Networks and Operative Multichanel Astrophysics, Lomonosov MSU PRESS, 591pp.\nhttp : // www.pereplet.ru/lipunov/625.html\n",
  "createdOn": 1772565433382,
  "submitter": "Vladimir Lipunov at Moscow State U/Krylov Obs <lipunov@xray.sai.msu.ru>",
  "circularId": 43912,
  "subject": "Fermi GRB 260303B: Global MASTER-Net observations report",
  "submittedHow": "email"
}