[vsnet-grb-info 15820] Konus-Wind observation of GRB 141121A

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  17108
SUBJECT: Konus-Wind observation of GRB 141121A
DATE:    14/11/28 14:34:54 GMT
FROM:    Dmitry Svinkin at Ioffe Institute  <svinkin at mail.ioffe.ru>

S. Golenetskii, R.Aptekar, D. Frederiks, V. Pal'shin, P. Oleynik,
M. Ulanov, D. Svinkin, A. Tsvetkova, A.Lysenko, and T. Cline,
on behalf of the Konus-Wind team, report:

The long GRB 141121A (Swift-BAT trigger #619182: Lien et al., GCN 17075;
Krimm et al., GCN 17083; MAXI/GSC detection: Honda et al., GCN 17077)
was detected by Konus-Wind in the waiting mode.

The burst light curve shows two emission episodes. The first started at 
~T0(BAT)-870 s with a duration of about 190 s and the second weaker 
episode, which corresponds to the first BAT episode reported in GCN 
17075, started at ~T0(BAT)+50 s with a duration of about 270 s. The 
second BAT episode (from T0(BAT)+550 to T0(BAT)+675 s) is not seen in KW 
data.

The first KW episode is likely related to GRB 141121A, since the KW 
ecliptic latitude response and IPN localization of the episode are 
consistent with the position of GRB 141121A. The details of the IPN 
localization will be given in a forthcoming GCN circular. During the 
first episode the burst source was outside the BAT FoV (private 
communication with the BAT team).

The total burst duration is about 1200 s. Such a long duration and long 
periods of low-level emission or quiescence is common for ultra-long GRB.

The KW light curve contains several data gaps. One of them (from 
~T0(BAT)-670 s to ~T0(BAT)-270 s) may bias the estimated duration of the 
first episode. The MAXI/GSC detection at ~T0(BAT)-356 s falls into this gap.

As observed by Konus-Wind, the first episode had a fluence of ~8x10^-6 
erg/cm2 and a 2.944 s peak flux, measured from ~T0(BAT)-752 s, of 
~2x10^-7 erg/cm2/s (both estimated in the 20 keV - 10  MeV energy 
range). The second episode had a fluence of ~6x10^-6 erg/cm2 estimated 
in the same energy range.

Assuming the redshift z=1.47 (Perley et al., GCN 17081)
and a standard cosmology model with H_0 = 70 km/s/Mpc,
Omega_M = 0.27, and Omega_Lambda = 0.73,
we estimate the following rest-frame parameters:
the isotropic energy release E_iso is ~8x10^52 erg,
the peak luminosity L_iso is ~10^51 erg/s.

The K-W light curve of this burst is available at
http://www.ioffe.ru/LEA/GRBs/GRB141121A/