Konus-Wind observation of GRB 180626B
Abstract
The short-duration GRB 180626B (IPN Triangulation: Hurley et al., GCN Circ. 22863) triggered Konus-Wind at T0=6442.786 s UT (01:47:22.786). The burst light curve shows a single pulse which starts at ~T0-0.1 s and has a total duration of ~0.3 s. The emission is seen up to ~2 MeV. As observed by Konus-Wind, the burst had a fluence of 7.69(-1.24,+1.35)x10^-7 erg/cm2, and a 16-ms peak flux, measured from T0+0.004 s, of 7.35(-2.79,+3.01)x10^-6 erg/cm2/s (both in the 20 keV - 10 MeV energy range). The time-averaged spectrum of the burst (measured from T0 to T0+0.192 s) is best fit in the 20 keV - 4 MeV range by a power law with exponential cutoff model: dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep) with alpha = -0.13(-0.54,+0.73) and Ep = 218(-43,+60) keV (chi2 = 23/26 dof). Fitting by a GRB (Band) model yields the same alpha and Ep, and an upper limit on the high energy photon index: beta < -2.7 (chi2 = 23/25 dof). The spectrum near the maximum count rate (measured from T0 to T0+0.064 s) is best fit in the 20 keV - 4 MeV range by a power law with exponential cutoff model with alpha = -0.08(-0.59,+0.87) and Ep = 294(-70,+116) keV (chi2 = 14/16 dof). Fitting by a GRB (Band) model yields the same alpha and Ep, and an upper limit on the high energy photon index: beta < -2.3 (chi2 = 14/15 dof). The Konus-Wind light curve of this GRB is available at http://www.ioffe.ru/LEA/GRBs/GRB180626_T06442/ All the quoted errors are at the 90% confidence level. All the quoted values are preliminary.
- Publication:
-
GRB Coordinates Network
- Pub Date:
- June 2018
- Bibcode:
- 2018GCN.22866....1K