GRB 240122B
GCN Circular 35606
Subject
GRB 240122B: Glowbug gamma-ray detection
Date
2024-01-23T17:26:28Z (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, D. Kocevski (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 240122B, which was also detected by CALET/CGBM (Trigger 1389985993).
Using an adaptive window with a resolution of 32-ms, the burst onset is determined to be 2024-01-22 19:16:24.160 with a duration of 21.5 s and a total significance of about 28.9 sigma. The light curve comprises a single peak.
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=2.2 and a cutoff energy ("Epeak") of 211 keV. The modeled 10-10000 keV fluence is 2.0e-06 erg/cm^2.
The best-fit localization is RA, Decl. (J2000, deg) = 22.8, 59.3 with a radius of 12.4 deg (95% confidence), with a highly uncertain systematic uncertainty.
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
Distribution Statement A: Approved for public release. Distribution is unlimited.
GCN Circular 35623
Subject
GRB 240122B: CALET Gamma-Ray Burst Monitor detection
Date
2024-01-24T20:04:13Z (a year ago)
From
Yuta Kawakubo at Louisiana State University <kawakubo1@lsu.edu>
Via
Web form
S. Ricciarini (U of Florence), A. Yoshida, T. Sakamoto,
S. Sugita (AGU), Y. Kawakubo (LSU), K. Yamaoka (Nagoya U),
S. Nakahira (JAXA), Y. Asaoka (ICRR), S. Torii, Y. Akaike,
K. Kobayashi (Waseda U), Y. Shimizu, T. Tamura (Kanagawa U),
N. Cannady (GSFC/UMBC), M. L. Cherry (LSU),
P. S. Marrocchesi (U of Siena),
and the CALET collaboration:
The long GRB 240122B (Glowbug gamma-ray detection:
Cheung et al., GCN Circ. 35606) triggered the CALET
Gamma-ray Burst Monitor (CGBM) at 19:16:26.96 UTC
on 22 January 2024
(http://cgbm.calet.jp/cgbm_trigger/flight/1389985993/).
The burst signal was seen by HXM2 and SGM.
The burst light curve shows a double-peaked structure that starts
at T-57.2 sec, peaks at T+9.0 sec, and ends at T+17.1 sec.
The T90 and T50 durations measured by the SGM data are
69.2 +/- 1.9 sec and 32.2 +/- 19.7 sec (40-1000 keV), respectively.
The ground-processed light curve is available at
http://cgbm.calet.jp/cgbm_trigger/ground/1389985993/index.html
The CALET data used in this analysis are provided by
the Waseda CALET Operation Center located at Waseda University.