TITLE: GCN CIRCULAR NUMBER: 11864 SUBJECT: GRB 110402A: early optical limit by "Pi of the Sky" DATE: 11/04/02 10:16:16 GMT FROM: Grzegorz Wrochna at Soltan Inst.for Nuclear Studies M.Sokolowski,T.Batsch,A.Majcher,A.Majczyna,K.Nawrocki,J.Uzycki,G.Wrochna (IPJ, Swierk), M.Cwiok,W.Dominik,L.W.Piotrowski,A.F.Zarnecki (University of Warsaw), K.Malek,L.Mankiewicz,R.Opiela,M.Siudek,V.Repei (CFT PAN), G.Kasprowicz,M.Zaremba (Warsaw University of Technology), from the "Pi of the Sky" collaboration (http://grb.fuw.edu.pl ). M. Jelinek and A. J.Castro-Tirado (IAA-CSIC Granada) on behalf of a larger collaboration. The wide field "Pi of the Sky North" apparatus installed in the BOOTES-1 station at ESAt/INTA-CEDEA in Mazagon (Huelva, Spain; http://grb.fuw.edu.pl/pi/index.html#piinta_site.htm ) observed field of GRB 110402A at the time of Fermi-GMB and Swift-BAT triggers. No new source brighter than 11 mag has been identified on 10s exposures: t_start - t0 start (UT) end (UT) 3-sigma limit -6 00:12:52 00:13:02 11.0 +7 00:13:05 00:13:15 11.0 where limit is based on the reference star magnitudo in V filter.