GCN Circular 35013
Subject
GRB 231106A: Glowbug gamma-ray detection
Date
2023-11-13T15:39:22Z (a year ago)
From
C.C. Cheung at Naval Research Lab <Teddy.Cheung@nrl.navy.mil>
Via
Web form
C.C. Cheung, M. Kerr, J. E. Grove, R. Woolf (NRL), A. Goldstein (USRA), C.A. Wilson-Hodge (MSFC), and M.S. Briggs (UAH) report:
The Glowbug gamma-ray telescope [1,2], operating on the International Space Station, reports the detection of GRB 231106A, which was also detected by Fermi/GBM, CALET, and AstroSat/CZTI (GCN 34956, 34965, 34966).
Using an adaptive window with a resolution of 32-ms, the burst onset is determined to be 2023-11-06 18:12:49.696. The light curve comprises an initial peak followed by a multi-peaked structure as observed by CALET (GCN 34965).
In the Glowbug data, the initial peak has a duration of 6.1 s and a total significance of about 24.1 sigma. Using a standard power-law function with an exponential high-energy cutoff [3] to model the emission over this duration results in a photon index dN/dE~E^x of x=0.4 and a cutoff energy ("Epeak") of 356 keV. The modeled 10-10000 keV fluence is 1.9e-06 erg/cm^2.
The onset of the later multi-peaked structure observed by Glowbug is determined to be 2023-11-06 18:13:18.368 with a duration of 26.6 s and a total significance of about 46.1 sigma. Using a standard power-law function with an exponential high-energy cutoff to model the emission over this duration results in a photon index of x=2.0 and an Epeak of 204 keV. The modeled 10-10000 keV fluence is 4.2e-06 erg/cm^2.
The analysis results presented here are preliminary and use a response function that lacks a detailed characterization of the surrounding passive structure of the ISS.
Glowbug is a NASA-funded technology demonstrator for sensitive, low-cost gamma-ray transient telescopes developed, built, and operated by the U.S. Naval Research Laboratory (NRL) with support from the University of Alabama in Huntsville, USRA, and NASA MSFC. It was launched on 2023 March 15 aboard the Department of Defense Space Test Program’s STP-H9 to the ISS. The detector comprises 12 large-area (15 cm x 15 cm) CsI:Tl panels covering the surface of a half cube, and two hexagonal (5-cm diameter, 10-cm length) CLLB scintillators, giving it a large field of view (instantaneous FoV ~2/3 sky) over a wide energy band of 50 keV to >2 MeV.
[1] Grove, J.E. et al. 2020, Proc. Yamada Conf. LXXI, arXiv:2009.11959
[2] Woolf, R.S. et al. 2022, Proc. SPIE, 12181, id. 121811O
[3] Goldstein, A. et al. 2020, ApJ 895, 40, arXiv :1909.03006
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