TITLE: GCN CIRCULAR NUMBER: 15238 SUBJECT: Fermi Trigger 401326696: MASTER prompt optical observations DATE: 13/09/21 12:42:39 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://93.180.27.230:8080/) synchronously observed 35% part of FERMI GRB130919A (trigger 401326696) error box before, during and after the trigger. Since 40 sec after the trigger cameras pointed to FERMI alert our FOV cover 95% part of error box. We haven`t found optical transient within FERMI error-box our first (5 s exposure) set. The 5-sigma upper limit has been about 12.0 mag. The 5-sigma upper limit on coadd first 30 images is about 13.0 mag. The first seconds movie locate here http://master.sai.msu.ru/static/GRB130919A.gif Our cameras are continuously imaging the sky with 5 sec exposures. The more accurat error box (by IPN) is requied. The message may be cited.