GRB 240312A
GCN Circular 35917
Subject
GRB 240312A: GECAM detection of a long burst
Date
2024-03-13T03:12:08Z (a year ago)
From
wenlongzhang2018@163.com
Via
Web form
Wen-Long Zhang, Shao-Lin Xiong, Xiao-Yun Zhao report on behalf of the GECAM team:
GECAM-B was triggered in-flight by a long burst, GRB 240312A, at 2024-03-12T14:02:10.550 UTC (T0). INTEGRAL/SPI-ACS was also triggered by this burst.
According to the GECAM-B light curves, this burst shows single-pulses with a total duration of ~5 sec.
According to the in-flight software, GECAM-B localized this burst to the following position (J2000):
Ra: 13.86 deg
Dec: 2.45 deg
Err: 2.74 deg (1-sigma, statistical only)
The time-averaged spectrum of GECAM-B realtime data from about T0-0.2 to T0+3.8 s could be
adequately fit by a Band function with a flux about 2.09E-6 erg/cm^2/s in 20-1000 keV.
We note that these results are very preliminary. Refined analysis will be reported later.
Gravitational wave high-energy Electromagnetic Counterpart All-sky Monitor (GECAM) mission originally consists of two microsatellites (GECAM-A and GECAM-B) launched in December 2020. As the third member of GECAM constellation, GECAM-C was launched onboard SATech-01 experimental satellite in July 2022. GECAM mission is funded by the Chinese Academy of Sciences (CAS).
GCN Circular 35921
Subject
GRB 240312A: Glowbug gamma-ray detection
Date
2024-03-13T19:21:31Z (a year ago)
From
C.C. Cheung at Naval Research Lab <Teddy.Cheung@nrl.navy.mil>
Via
Web form
C.C. Cheung, R. Woolf, M. Kerr, J.E. Grove (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 240312A, which was also detected by GECAM-B (GCN 35917) and INTEGRAL/SPI-ACS (Trigger 10625).
Using an adaptive window with a resolution of 32-ms, the burst onset is determined to be 2024-03-12 14:02:09.584 with a duration of 2.0 s and a total significance of about 8.1 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 poorly constrained power-law index and a cutoff energy ("Epeak") of 185 keV. The modeled 10-10000 keV fluence is 2.7e-07 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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