GCN Circular 24170
Subject
LIGO/Virgo S190425z: INTEGRAL SPI-ACS prompt observation
Date
2019-04-25T10:27:09Z (6 years ago)
From
Alexei Pozanenko at IKI, Moscow <apozanen@iki.rssi.ru>
P. Minaev, A. Pozanenko, S. Grebenev, I. Chelovekov on behalf of IKI GRB FuN collaboration report:
We used public data of SPI-ACS to perform a search for possible EM-counterpart of LIGO/Virgo S190425z. Here we report preliminary analysis of SPI-ACS data available. After trigger time of S190425z (G330561) we found two pulses with time since trigger, duration, significance and fluence (in counts) above a background as following
+0.5 s, 0.4 s, 3.6 sigma, 900 +/- 250
+6 s, 1 s, 4 sigma, 1620 +/- 400
The significance of the second pulse is somewhat larger in comparison with reported early in GCN 24169 (Martin-Carillo et al.)
We estimated fluence of first and second pulses in the energy range 75 - 1000 keV as (9.0 +- 0.3) * 10^-8 erg/cm2 and (1.6 +- 0.4 ) * 10^-7
erg/cm2, respectively. It corresponds to E_iso (2.5 +/- 0.7) * 10^47 erg and (4.5 +/- 1.1) * 10^47 erg assuming distance 154.6 Mpc.
We do no found any extended emission up to T0+270 s after trigger.
The boresight of the center of the eror box localization (RA, Dec 16 10
18.75, 22 49 53.0609) is about 31 degrees.