TITLE: GCN CIRCULAR NUMBER: 30112 SUBJECT: Fermi GRB 210601A: Global MASTER-Net observations report DATE: 21/06/02 02:32:35 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs V. Lipunov, E. Gorbovskoy, V.Kornilov, N.Tyurina, P.Balanutsa, A.Kuznetsov, F.Balakin, V.Vladimirov, D. Vlasenko, I.Gorbunov, D.Zimnukhov, V.Senik, T.Pogrosheva, D.Kuvshinov, D. Cheryasov (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, O.Ershova (Irkutsk State University, API), A. Tlatov, D. Dormidontov (Kislovodsk Solar Station of the Pulkovo Observatory), V. Yurkov, A. Gabovich, Yu. Sergienko (Blagoveschensk Educational State University) MASTER-Kislovodsk robotic telescope (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in Russia (Lomonosov MSU, Kislovodsk Solar Station of Pulkovo observatory) started inspect of the Fermi GRB 210601A ( Fermi GBM team, GCN 30111) errorbox 17545 sec after notice time and 17557 sec after trigger time at 2021-06-01 22:14:50 UT, with upper limit up to 17.4 mag. The observations began at zenith distance = 53 deg. The sun altitude is -23.1 deg. MASTER-IAC robotic telescope located in Spain (IAC Teide Observatory) started inspect of the Fermi GRB 210601A errorbox 25066 sec after notice time and 25077 sec after trigger time at 2021-06-02 00:20:11 UT, with upper limit up to 19.0 mag. The observations began at zenith distance = 57 deg. The sun altitude is -38.9 deg. The galactic latitude b = -8 deg., longitude l = 7 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=1626114 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 17647 | 2021-06-01 22:14:50 | MASTER-Kislovodsk | (19h 02m 09.26s , -07d 18m 48.6s) | C | 180 | 16.9 | 17647 | 2021-06-01 22:14:50 | MASTER-Kislovodsk | (19h 06m 27.80s , -07d 43m 31.9s) | C | 180 | 17.2 | 17847 | 2021-06-01 22:18:11 | MASTER-Kislovodsk | (19h 02m 43.26s , -05d 50m 39.1s) | C | 180 | 17.1 | 17848 | 2021-06-01 22:18:11 | MASTER-Kislovodsk | (19h 07m 01.71s , -06d 15m 20.8s) | C | 180 | 17.4 | 18048 | 2021-06-01 22:21:31 | MASTER-Kislovodsk | (19h 02m 12.53s , -07d 18m 39.2s) | C | 180 | 16.6 | 18048 | 2021-06-01 22:21:31 | MASTER-Kislovodsk | (19h 06m 31.53s , -07d 43m 23.3s) | C | 180 | 16.9 | 18249 | 2021-06-01 22:24:52 | MASTER-Kislovodsk | (19h 02m 40.58s , -05d 50m 08.7s) | C | 180 | 17.1 | 18249 | 2021-06-01 22:24:52 | MASTER-Kislovodsk | (19h 06m 59.31s , -06d 14m 49.8s) | C | 180 | 17.3 | 18449 | 2021-06-01 22:28:12 | MASTER-Kislovodsk | (19h 02m 06.55s , -07d 18m 28.5s) | C | 180 | 16.6 | 18449 | 2021-06-01 22:28:12 | MASTER-Kislovodsk | (19h 06m 25.83s , -07d 43m 11.9s) | C | 180 | 16.8 | 18649 | 2021-06-01 22:31:32 | MASTER-Kislovodsk | (19h 02m 47.47s , -05d 50m 04.4s) | C | 180 | 15.7 | 18649 | 2021-06-01 22:31:32 | MASTER-Kislovodsk | (19h 07m 06.66s , -06d 14m 43.8s) | C | 180 | 16.1 | 25168 | 2021-06-02 00:20:11 | MASTER-IAC | (19h 05m 57.87s , -07d 29m 43.1s) | C | 180 | 17.2 | 25168 | 2021-06-02 00:20:11 | MASTER-IAC | (18h 57m 48.97s , -07d 23m 54.5s) | C | 180 | 17.1 | 25583 | 2021-06-02 00:27:06 | MASTER-IAC | (19h 05m 57.28s , -07d 31m 47.0s) | C | 180 | 17.2 | 25583 | 2021-06-02 00:27:06 | MASTER-IAC | (18h 57m 48.34s , -07d 25m 59.1s) | C | 180 | 17.1 | 25984 | 2021-06-02 00:33:47 | MASTER-IAC | (19h 06m 01.32s , -07d 30m 03.4s) | C | 180 | 17.2 | 25984 | 2021-06-02 00:33:47 | MASTER-IAC | (18h 57m 52.02s , -07d 24m 16.0s) | C | 180 | 17.4 | 27984 | 2021-06-02 01:07:07 | MASTER-IAC | (19h 06m 38.06s , -06d 00m 46.2s) | C | 180 | 17.4 | 27984 | 2021-06-02 01:07:07 | MASTER-IAC | (18h 58m 29.15s , -05d 55m 05.1s) | C | 180 | 17.4 | 28388 | 2021-06-02 01:13:51 | MASTER-IAC | (19h 06m 33.12s , -06d 00m 20.4s) | C | 180 | 17.5 | 28388 | 2021-06-02 01:13:51 | MASTER-IAC | (18h 58m 24.56s , -05d 54m 37.4s) | C | 180 | 17.4 | 28588 | 2021-06-02 01:17:11 | MASTER-IAC | (19h 35m 20.14s , -07d 38m 19.1s) | C | 180 | 18.3 | 28588 | 2021-06-02 01:17:11 | MASTER-IAC | (19h 34m 30.41s , -07d 32m 50.5s) | C | 180 | 18.5 | 28789 | 2021-06-02 01:20:32 | MASTER-IAC | (19h 35m 12.98s , -07d 39m 21.4s) | C | 180 | 18.3 | 28789 | 2021-06-02 01:20:32 | MASTER-IAC | (19h 34m 23.45s , -07d 33m 52.2s) | C | 180 | 18.6 | 28989 | 2021-06-02 01:23:52 | MASTER-IAC | (19h 35m 20.18s , -07d 39m 20.7s) | C | 180 | 18.3 | 28989 | 2021-06-02 01:23:52 | MASTER-IAC | (19h 34m 30.83s , -07d 33m 50.7s) | C | 180 | 18.7 | 29271 | 2021-06-02 01:28:34 | MASTER-IAC | (19h 35m 13.32s , -07d 37m 34.4s) | C | 180 | 18.9 | 29271 | 2021-06-02 01:28:34 | MASTER-IAC | (19h 34m 23.81s , -07d 31m 41.9s) | C | 180 | 18.7 | 29471 | 2021-06-02 01:31:54 | MASTER-IAC | (19h 35m 13.40s , -07d 39m 08.1s) | C | 180 | 18.9 | 29471 | 2021-06-02 01:31:54 | MASTER-IAC | (19h 34m 23.87s , -07d 33m 14.0s) | C | 180 | 18.6 | 29671 | 2021-06-02 01:35:14 | MASTER-IAC | (19h 35m 17.00s , -07d 37m 47.7s) | C | 180 | 19.0 | 29671 | 2021-06-02 01:35:14 | MASTER-IAC | (19h 34m 27.59s , -07d 31m 53.5s) | C | 180 | 18.7 | 30072 | 2021-06-02 01:41:55 | MASTER-IAC | (19h 06m 33.09s , -06d 00m 31.6s) | C | 180 | 18.1 | Filter C is a clear (unfiltred) band. The observation and reduction will continue. The message may be cited.