GRB 240117A
GCN Circular 35569
Subject
GRB 240117A: Glowbug gamma-ray detection
Date
2024-01-18T21:30:43Z (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 240117A, which was also detected by CALET/CGBM (Trigger 1389556167) and INTEGRAL/SPI-ACS (Trigger 10476).
Using an adaptive window with a resolution of 32-ms, the burst onset is determined to be 2024-01-17 19:52:29.928 with a duration of 9.2 s and a total significance of about 35.3 sigma. The light curve comprises two primary peaks.
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=1.9 and a cutoff energy ("Epeak") of 264 keV. The modeled 10-10000 keV fluence is 3.8e-06 erg/cm^2.
The best-fit localization is RA, Decl. (J2000, deg) = 229.6, 3.1 with a radius of 18.7 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 35574
Subject
GRB 240117A: AstroSat CZTI detection
Date
2024-01-19T04:56:39Z (a year ago)
From
Gaurav Waratkar at IIT Bombay <gauravwaratkar@iitb.ac.in>
Via
Web form
J. Joshi (IUCAA), G. Waratkar (IITB), A. Vibhute (IUCAA), V. Bhalerao (IITB), D. Bhattacharya (Ashoka University/IUCAA), A. R. Rao (IUCAA/TIFR), and S. Vadawale (PRL) report on behalf of the AstroSat CZTI collaboration:
Analysis of AstroSat CZTI data with the CIFT framework (Sharma et al., 2021, JApA, 42, 73) showed the detection of a long-duration GRB 240117A which was also detected by Calet (Trigger Num. 1389556167), Integral-SPIACS (Trigger Num. 10476), and Glowbug (Cheung et al., GCN Circ. 35569).
The source was detected in the CZT detectors in the 20-200 keV energy range. The light curve peaks at 2024-01-17 19:52:36.50 UTC. The measured peak count rate associated with the burst is 156 (+35, -30) counts/s above the background in the combined data of three quadrants (out of four), with a total of 451 (+136, -161) counts. The local mean background count rate was 292 (+4, -3) counts/s. Using cumulative rates, we measure a T90 of 3.62 (+3.5, -1.6) s.
The source was also detected in the CsI anticoincidence (Veto) detector in the 100-500 keV energy range. The light curve peaks at 2024-01-17 19:52:35.72 UTC. The measured peak count rate associated with the burst is 208 (+80, -23) counts/s above the background in the combined data of three quadrants (out of four), with a total of 937 (+206, -219) counts. The local mean background count rate was 1475 (+7, -8) counts/s. We measure a T90 of 5.13 (+0.54, -1.39) s from the cumulative Veto light curve.
CZTI is built by a TIFR-led consortium of institutes across India, including VSSC, URSC, IUCAA, SAC, and PRL. The Indian Space Research Organisation funded, managed, and facilitated the project.
CZTI GRB detections are reported regularly on the payload site at:
http://astrosat.iucaa.in/czti/?q=grb
GCN Circular 35582
Subject
GRB 240117A: CALET Gamma-Ray Burst Monitor detection
Date
2024-01-19T18:53:39Z (a year ago)
From
Yuta Kawakubo at Louisiana State University <kawakubo1@lsu.edu>
Via
Web form
M. L. Cherry (LSU) 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),
S. Ricciarini (U of Florence), P. S. Marrocchesi (U of Siena),
and the CALET collaboration:
The long GRB 240117A (Glowbug gamma-ray detection: Cheung
et al., GCN Circ 35569; AstroSat CZTI detection: Joshi et al., GCN
Circ 35574) triggered the CALET Gamma-ray Burst Monitor (CGBM)
at 19:52:31.44 UTC on 17 January 2024
(http://cgbm.calet.jp/cgbm_trigger/flight/1389556167/).
The burst signal was seen by only the SGM detector.
The burst light curve shows a single pulse that starts at T+2.4 sec,
peaks at T+4.5 sec, and ends at T+8.8 sec. The T90 and T50 durations
measured by the SGM data are 5.7 +/- 0.6 sec and 2.6 +/- 0.3 sec
(40-1000 keV), respectively.
The ground-processed light curve is available at
http://cgbm.calet.jp/cgbm_trigger/ground/1389556167/index.html
The CALET data used in this analysis are provided by
the Waseda CALET Operation Center located at Waseda University.