TITLE: GCN CIRCULAR NUMBER: 16875 SUBJECT: GRB 140930B: MASTER early possible OT detection DATE: 14/10/02 06:41:06 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs E. Gorbovskoy, V. Lipunov, M.Pruzhinskaya, V.Kornilov, D.Kuvshinov, N.Tyurina, P.Balanutsa, A.Kuznetsov, V.V.Chazov, D.Denisenko Lomonosov Moscow State University, Sternberg Astronomical Institute, Moscow State University A. Tlatov, A.V. Parhomenko, D. Dormidontov, V.Sennik Kislovodsk Solar Station of the Pulkovo Observatory V.Yurkov, Yu.Sergienko, D.Varda, E.Sinyakov, A. Gabovich Blagoveschensk Educational State University, Blagoveschensk K.Ivanov, S.Yazev, N.M.Budnev, O.Gres, O.Chuvalaev, V.A.Poleshchuk Irkutsk State University V.Krushinski, I.Zalozhnih, A. Popov Ural Federal University, Kourovka Hugo Levato and Carlos Saffe Instituto de Ciencias Astronomicas, de la Tierra y del Espacio (ICATE) Claudio Mallamaci, Carlos Lopez and Federico Podest Observatorio Astronomico Felix Aguilar (OAFA) Two MASTER II twin robotic telescope (MASTER-Net: http://observ.pereplet.ru) located in Blagoveschensk and Kislovodsk was pointed to the GRB140930B (Pasquale et. al GCN 16857) 21 and 36 sec after notice time and 39 and 54 sec after trigger time respectively. So we have 4 first images in four different polarization started after 21 sec (Blagoveschensk) and 36 sec (Kislovodsk) with 10 sec exposure. We found 3-sigma OT on one tube image in Blagoveschensk at the WHT position (Tanvir et. al, GCN16861, Fong et. al. GCN16863) with m = 16+-0.5 mag. The OT seen at one first image only. The image with OT is available at http://master.sai.msu.ru/static/GRB/GRB140930B_MASTER_OT.png We do not see OT (Tanvir et. al GCN16857, Fong et. al. GCN16857) on three tube images on single and coadd images. The analysis strongly is complicated by presence of very bright star (USNO B1 1142-0005722 ~14m) close to OT position. The upper limits received by MASTER are given in the table below: t_start | t-t_mid | exptime | filt | lim | site | coadd --------------------------+---------+------+------+------+------- 19:42:21.909 | 44 sec | 10 | P/ | 16.4 | A | 1 19:42:21.909 | 44 sec | 10 | P\ | 15.7 | A | 1* 19:42:36.837 | 59 sec | 10 | P| | 15.6 | K | 1 19:42:36.837 | 59 sec | 10 | P- | 16.0 | K | 1 19:42:21.909 | 70 sec | 40 | P/ | 17.3 | A | 3 19:42:36.837 | 98 sec | 50 | P- | 16.9 | K | 3 19:42:21.909 | 130 sec | 130 | P/ | 18.5 | A | 6 19:44:26.834 | 243 sec | 120 | P- | 18.0 | K | 3 19:42:36.837 | 188 sec | 170 | P- | 18.6 | K | 6 19:42:36.837 | 692 sec | 1060 | P- | 19.9 | K | 13 19:42:21.909 | 698 sec | 1160 | P/ | 19.7 | A | 14 20:29:14.938 | 6120 sec | 5400 | C |~21.5 | K | 30 * possible OT C is our white (clear) band which is well described by a parity 0.8R+0.2B (USNO B1). P/ and P\ is a polarization filter which are oriented at an angle 45 and 135 degrees to RA axis respectivel. P- and P| is a polarization filter which are oriented at an angle 0 and 90 degrees to RA axis respectivel. This message may be cited.