TITLE: GCN CIRCULAR NUMBER: 22444 SUBJECT: GRB180224A: Global MASTER-Net bright OT detection DATE: 18/02/25 10:33:21 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs V.Vladimirov, V. Lipunov, E.Gorbovskoy, N.Tyurina, V.Kornilov, D.Zimnukhov, A.Krylov, I.Gorbunov, P.Balanutsa, A.Kuznetsov, V.Chazov, D. Kuvshinov (Lomonosov Moscow State University, SAI) A. Tlatov, V.Senik, D. Dormidontov (Kislovodsk Solar Station of the Pulkovo Observatory) D.Buckley, S. Potter (South African Astronomical Observatory), O.Gres, N.M.Budnev (Irkutsk State University), V.Yurkov, A.Gabovich, Yu.Sergienko (Blagoveschensk Educational State University, Blagoveschensk), R.Podesta, C.Lopez, F. Podesta (Observatorio Astronomico Felix Aguilar (OAFA), National University of San Juan, Argentina), H. Levato, C. Saffe (Instituto de Ciencias Astronomicas,de la Tierra y del Espacio (ICATE), San Juan, Argentina), R. Rebolo, M. Serra, N. Lodieu, G. Israelian, L. Suarez-Andres (The Instituto de Astrofisica de Canarias), MASTER-Kislovodsk (Russia) robotic telescope (MASTER-Net: http://observ.pereplet.ru) located in Kislovodsk was pointed to the GRB180224.93 21 sec after notice time and 37 sec after trigger time at 2018-02-24 22:21:44 UT. On our unfiltered polarizing exposures set we found 1 bright optical transient within SWIFT error-box (ra=202.658 dec=38.0878 r=0.05) brighter then 18.1. RA,DEC = 13h 30m 44.057s , +38d 04m 44.55 s Error = 0.1 arcsec maximal magnitute ~ 16.7 The 5-sigma upper limit has been about 18.1mag The message may be cited. ==================================================================== The observations made on zenit distance = 23 degrees, galaxy latitude b = 76 degree. The moon (68 % bright part) is 16 degrees above the horizon. The distance between moon and object is 97 degrees. The sun altitude is -53.0 degree. The object can be observed till sunrise at 2018-02-25 03:53:29 UT. MASTER-SAAO robotic telescope (MASTER-Net: http://observ.pereplet.ru) located in SAAO was pointed to the GRB180224.94 92 sec after notice time and 176 sec after trigger time at 2018-02-24 22:24:12 UT. On our first set we not found optical transient within SWIFT error-box (ra=202.638 dec=38.0819 r=0.1) brighter then 15.8. The 5-sigma upper limit has been about 15.8 mag The message may be cited. The observations made on high zenit distance = 82 degrees, galaxy latitude b = 76 degree. The moon (68 % bright part) is 6 degrees above the horizon. The distance between moon and object is 97 The sun altitude is -48.3 degree. The object can be observed till sunrise at 2018-02-25 04:21:26. This message can be cited.