TITLE: GCN CIRCULAR NUMBER: 29822 SUBJECT: IceCube Alert 210416.09: Global MASTER-Net observations report DATE: 21/04/16 04:39:16 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-IAC robotic telescope (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in Spain (IAC Teide Observatory) started inspect of the IceCube Alert 210416.09 (trigger No 31863828,12h 56m 45.00s , -06d 17m 19.0s, R=19.85) errorbox 6940 sec after trigger time at 2021-04-16 03:59:37 UT, with upper limit up to 19.5 mag. The observations began at zenith distance = 62 deg. The sun altitude is -32.7 deg. The galactic latitude b = 56 deg., longitude l = 306 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=1593637 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 7030 | 2021-04-16 03:59:37 | MASTER-IAC | (12h 59m 18.77s , -06d 13m 19.3s) | C | 180 | 18.9 | 7180 | 2021-04-16 03:59:37 | MASTER-IAC | (12h 59m 18.76s , -06d 13m 19.6s) | C | 480 | 19.4 | Coadd 7030 | 2021-04-16 03:59:37 | MASTER-IAC | (12h 51m 10.34s , -06d 07m 56.9s) | C | 180 | 18.9 | 7180 | 2021-04-16 03:59:37 | MASTER-IAC | (12h 51m 10.35s , -06d 07m 57.0s) | C | 480 | 19.5 | Coadd 7230 | 2021-04-16 04:02:57 | MASTER-IAC | (12h 59m 22.08s , -06d 12m 04.9s) | C | 180 | 18.9 | 7230 | 2021-04-16 04:02:57 | MASTER-IAC | (12h 51m 13.52s , -06d 06m 44.3s) | C | 180 | 19.1 | 7400 | 2021-04-16 04:06:16 | MASTER-IAC | (12h 59m 15.74s , -06d 12m 41.0s) | V | 120 | 17.8 | 7400 | 2021-04-16 04:06:16 | MASTER-IAC | (12h 51m 07.18s , -06d 07m 20.9s) | R | 120 | 16.4 | Filter C is a clear (unfiltred) band. The observation and reduction will continue. The message may be cited.