[vsnet-grb-info 7762] ICSP VLF observation of GRB090424 from four receivers

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  9316
SUBJECT: ICSP VLF observation of GRB090424 from four receivers
DATE:    09/05/01 13:25:00 GMT
FROM:    Sandip K. Chakrabarti at S.N. Bose Nat. Centre for Basic Sci.  <chakraba at bose.res.in>

ICSP VLF observation of GRB090424 from four receivers

Sandip K. Chakrabarti (S. N. Bose Centre and ICSP), Sushanta K. Mondal (ICSP),
Asit Choudhury (ICSP, Malda branch), Achintya Chatterjee (ICSP, Malda Branch),
Narendra N. Patra (Univ. Pune) and D. Bhowmick (ICSP)

Three ICSP VLF receivers clearly observed the effects of GRB090424
(GCN#s 9223, 9230) on the ionosphere simultaneously. The subflare point
(16.8d N , 123.76d E) being closer to eastern India the signal was prominent.
Two receivers were kept at Kolkata (22.5N, 88.5d E)  at sixteen kilometers 
(~ 10 miles) apart, while a third receiver was kept at Malda (25d N, 88d E)
which is about 200 miles away. All the three receivers detected the GRB right
after triggering and the correlation of the signals were found excellent for
about ~100 seconds. Before the triggering, the correlation was poor. The signal
from a fourth ICSP receiver at Pune (~1000 miles from Kolkata) in western 
India (18.5d N, 74d N) was very poor.

A comparison of the smoothed signals can be found in allthree.jpg in
http://www.bose.res.in/~chakraba/grb090424-1.html. This message may be cited.