TITLE: GCN CIRCULAR NUMBER: 14501 SUBJECT: GRB 130425: MASTER-Net optical observations DATE: 13/04/29 12:59:52 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs H. Levato and C. Saffe Instituto de Ciencias Astronomicas, de la Tierra y del Espacio (ICATE) C. Mallamaci, C. Lopez and F. Podest Observatorio Astronomico Felix Aguilar (OAFA) E. Gorbovskoy, V. Lipunov, V. Kornilov, D. Denisenko, A. Kuznetsov, D. Kuvshinov, A. Belinski, N. Tyurina, N. Shatskiy, P. Balanutsa, D. Zimnukhov, V.V. Chazov Lomonosov Moscow State University, Sternberg Astronomical Institute A. Tlatov, A.V. Parhomenko, D. Dormidontov, V. Sennik Kislovodsk Solar Station of the Pulkovo Observatory K. Ivanov, S. Yazev, N.M. Budnev, O. Gres, O. Chuvalaev, V.A. Poleshchuk Irkutsk State University V. Yurkov, Yu. Sergienko, D. Varda, E. Sinyakov Blagoveschensk Educational State University, Blagoveschensk V. Krushinski, I. Zalozhnich, A. Popov, A. Bourdanov, A. Punanova Ural Federal University MASTER-ICATE robotic very wide field cameras (FOV=2x384 square degrees, D=72mm, f/1.2, 1 pix = 22 arcsec, http://observ.pereplet.ru) located in Argentina (Observatorio Astronomico Felix Aguilar, http://master.sai.msu.ru:8080/) were pointed to the GRB 130425A (von Kienlin, GCN 14442, K. Hurley et. al GCN 14446, S. Golenetskii et. al 14447) 40 sec after FERMI trigger Time at 2013-04-25 07:52:08 UT. We cover full IPN error box (K. Hurley et. al GCN 14446). We haven't found optical transient within IPN error box on our 5-s frames and on the coadded image made of 60 frames and total exposure of 300 seconds. The 3-sigma upper limit (with the reference to V magnitudes from Tycho-2 catalog) has been about 11.0 mag on single images and 13.0 mag on coadded image. The coverage map available here: http://master.sai.msu.ru/static/MASTER_ARG_GRB130425A_single.jpeg The reduction of the whole data set is continuing. This message can be cited.