TITLE: GCN CIRCULAR NUMBER: 33377 SUBJECT: Fermi GRB 230227A: Global MASTER-Net observations report DATE: 23/02/27 20:45:23 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs V. Lipunov, V.Kornilov, E.Gorbovskoy, K.Zhirkov, N.Tyurina, P.Balanutsa, A.Kuznetsov, D. Vlasenko, G.Antipov, D.Zimnukhov, V.Senik, E.Minkina, A.Chasovnikov, V.Topolev, D.Kuvshinov, D.Cheryasov, Ya.Kechin (Lomonosov Moscow State University, SAI, Physics Department), R. Podesta, C.Lopez, F. Podesta, C.Francile (Observatorio Astronomico Felix Aguilar OAFA), R. Rebolo, M. Serra (The Instituto de Astrofisica de Canarias), D. Buckley (South African Astronomical Observatory), O.A. Gres, N.M. Budnev (Irkutsk State University, API), L.Carrasco, J.R.Valdes, V.Chavushyan, V.M.Patino Alvarez, J.Martinez, A.R.Corella, L.H.Rodriguez (INAOE, Guillermo Haro Astrophysics Observatory), A. Tlatov, D. Dormidontov (Kislovodsk Solar Station of the Pulkovo Observatory), A. Gabovich, V.Yurkov (Blagoveschensk Educational State University) 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 GRB 230227A ( Fermi GBM team, GCN 33376) errorbox 27935 sec after notice time and 27945 sec after trigger time at 2023-02-27 18:07:48 UT, with upper limit up to 18.0 mag. Observations started at twilight. The observations began at zenith distance = 71 deg. The sun altitude is -11.4 deg. The galactic latitude b = -61 deg., longitude l = 335 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=2201434 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 27975 | 2023-02-27 18:07:48 | MASTER-SAAO | (23h 22m 43.55s , -50d 06m 48.8s) | C | 60 | 15.8 | 28055 | 2023-02-27 18:09:07 | MASTER-SAAO | (23h 03m 26.41s , -48d 11m 15.9s) | C | 60 | 14.7 | 28146 | 2023-02-27 18:10:39 | MASTER-SAAO | (23h 15m 26.92s , -48d 13m 00.1s) | C | 60 | 15.7 | 28533 | 2023-02-27 18:17:05 | MASTER-SAAO | (22h 54m 28.18s , -51d 59m 07.3s) | C | 60 | 16.4 | 28612 | 2023-02-27 18:18:25 | MASTER-SAAO | (23h 07m 21.20s , -51d 59m 54.1s) | C | 60 | 17.1 | 28703 | 2023-02-27 18:19:56 | MASTER-SAAO | (23h 19m 03.56s , -51d 59m 04.8s) | C | 60 | 17.4 | 28782 | 2023-02-27 18:21:15 | MASTER-SAAO | (23h 32m 10.32s , -52d 00m 19.3s) | C | 60 | 17.6 | 28956 | 2023-02-27 18:24:09 | MASTER-SAAO | (22h 59m 02.16s , -50d 06m 24.6s) | C | 60 | 17.1 | 29048 | 2023-02-27 18:25:40 | MASTER-SAAO | (23h 04m 37.58s , -53d 52m 45.1s) | C | 60 | 17.5 | 29138 | 2023-02-27 18:27:11 | MASTER-SAAO | (23h 18m 13.09s , -53d 54m 42.5s) | C | 60 | 17.8 | 29223 | 2023-02-27 18:28:36 | MASTER-SAAO | (23h 10m 16.61s , -50d 05m 00.7s) | C | 60 | 17.2 | 29314 | 2023-02-27 18:30:07 | MASTER-SAAO | (23h 22m 39.71s , -50d 05m 57.9s) | C | 60 | 17.9 | 29399 | 2023-02-27 18:31:32 | MASTER-SAAO | (23h 03m 25.78s , -48d 10m 31.1s) | C | 60 | 17.0 | 29489 | 2023-02-27 18:33:01 | MASTER-SAAO | (23h 15m 32.95s , -48d 11m 45.1s) | C | 60 | 17.5 | 29570 | 2023-02-27 18:34:23 | MASTER-SAAO | (22h 54m 24.11s , -52d 00m 20.0s) | C | 60 | 17.1 | 29659 | 2023-02-27 18:35:52 | MASTER-SAAO | (23h 07m 28.96s , -52d 00m 30.7s) | C | 60 | 17.9 | 29749 | 2023-02-27 18:37:22 | MASTER-SAAO | (23h 19m 08.93s , -51d 58m 50.7s) | C | 60 | 17.9 | 29829 | 2023-02-27 18:38:42 | MASTER-SAAO | (23h 32m 09.06s , -52d 00m 48.4s) | C | 60 | 18.0 | 29926 | 2023-02-27 18:40:18 | MASTER-SAAO | (22h 58m 57.37s , -50d 05m 19.4s) | C | 60 | 17.6 | 30005 | 2023-02-27 18:41:38 | MASTER-SAAO | (23h 04m 36.55s , -53d 52m 26.0s) | C | 60 | 18.0 | 30096 | 2023-02-27 18:43:09 | MASTER-SAAO | (23h 18m 17.75s , -53d 53m 39.5s) | C | 60 | 18.0 | 30175 | 2023-02-27 18:44:28 | MASTER-SAAO | (23h 26m 21.92s , -48d 12m 46.9s) | C | 60 | 17.9 | 31810 | 2023-02-27 19:11:42 | MASTER-SAAO | (23h 35m 15.88s , -50d 04m 17.8s) | C | 60 | 17.8 | 31810 | 2023-02-27 19:11:42 | MASTER-SAAO | (23h 33m 34.02s , -50d 04m 42.6s) | C | 60 | 17.2 | Filter C is a clear (unfiltred) band. The observation and reduction will continue. The message may be cited.