TITLE: GCN CIRCULAR NUMBER: 9317 SUBJECT: ICSP VLF observation of GRB090427 from two receivers DATE: 09/05/01 13:43:55 GMT FROM: Sandip K. Chakrabarti at S.N. Bose Nat. Centre for Basic Sci. ICSP VLF observation of GRB090427 from two receivers Sushanta K. Mondal (ICSP), Sandip K. Chakrabarti (S. N. Bose Centre and ICSP), Narendra N. Patra (Univ. Pune) and D. Bhowmick (ICSP) Two ICSP VLF receivers clearly observed the effects of GRB090427 (GCN#s 9277, 9296) on the ionosphere simultaneously. The subflare point (13.5d S, 28.2d E) being closer to western India the signal was prominent from our Pune receiver (18.5d N, 74d N) while it was weaker at our Kolkata (22.5N, 88.5d E) receiver in eastern India. These two stations were ~1000 miles apart. Both the receivers detected the GRB right after triggering and the correlation of the signals were found excellent for about ~70 seconds. Before the triggering, the correlation was poor. A comparison of the smoothed signals can be found in grb27GCN.jpg in http://www.bose.res.in/~chakraba/grb090427-1.html. This message may be cited.