GRB 240415A
GCN Circular 36381
Subject
GRB 240415A 1.3m DFOT Optical upper limit
Date
2024-05-03T13:09:26Z (a year ago)
From
ANSHIKA GUPTA at ARIES <anshika05180@gmail.com>
Via
Web form
Anshika Gupta (ARIES), Kuntal Misra (ARIES), Atul Kumar Singh (DDUGU) and Dimple (CMI) report:
We observed the field of GRB 240415A detected by Swift (GCN 36128 ) using the 1.3m Devasthal Fast Optical Telescope (DFOT) located at the Devasthal observatory of Aryabhatta Research Institute of observational sciencES (ARIES), Nainital, India. The observation started on 2024-04-16 at 15:29:51 UTC. Multiple frames of 300 sec exposure were acquired in the R band. We do not detect the optical afterglow (earlier reported in GCN 36122, GCN 36123, GCN 36124, GCN 36132) in the stacked image down to a limiting magnitude of 21.8. The photometric calibration is performed using the standard stars from the USNO-B1.0 catalog.
GCN Circular 36225
Subject
GRB 240415A: Swift-XRT refined Analysis
Date
2024-04-22T07:22:59Z (a year ago)
From
Phil Evans at U of Leicester <pae9@star.le.ac.uk>
Via
email
P.A. Evans (U. Leicester) reports on behalf of the Swift-XRT team:
We have analysed 5.4 ks of XRT data for GRB 240415A, from 3.3 ks to
26.8 ks after the BAT trigger. The data comprise 281 s in Windowed
Timing (WT) mode with the remainder in Photon Counting (PC) mode.
The light curve can be modelled with a power-law decay with a decay
index of alpha=0.97 (+/-0.09).
A spectrum formed from the PC mode data can be fitted with an absorbed
power-law with a photon spectral index of 2.18 (+/-0.16). The
best-fitting absorption column is 2.2 (+/-0.5) x 10^21 cm^-2, in
excess of the Galactic value of 2.5 x 10^20 cm^-2 (Willingale et al.
2013). The counts to observed (unabsorbed) 0.3-10 keV flux conversion
factor deduced from this spectrum is 3.3 x 10^-11 (4.9 x 10^-11) erg
cm^-2 count^-1.
A summary of the PC-mode spectrum is thus:
Total column: 2.2 (+/-0.5) x 10^21 cm^-2
Galactic foreground: 2.5 x 10^20 cm^-2
Excess significance: 6.4 sigma
Photon index: 2.18 (+/-0.16)
The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/01221874.
This circular is an official product of the Swift-XRT team.
GCN Circular 36148
Subject
GRB 240415A: Glowbug gamma-ray detection
Date
2024-04-17T14:55:09Z (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 240415A, which was also detected by Fermi/GBM (GCN 36107, 36134) and Swift/BAT (GCN 36108, 36143).
Using an adaptive window with a resolution of 32-ms, the burst onset is determined to be 2024-04-15 06:26:52.488 with a duration of 8.2 s and a total significance of about 17.7 sigma. The light curve comprises two primary peaks at ~T0+1s and ~T0+4s.
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 36143
Subject
GRB 240415A: Swift-BAT refined analysis
Date
2024-04-17T02:09:31Z (a year ago)
From
Mike Moss at NASA GSFC <mikejmoss3@gmail.com>
Via
Web form
M. J. Moss (GSFC), S. D. Barthelmy (GSFC),
H. A. Krimm (NSF), S. Laha (GSFC/UMBC),
A. Y. Lien (U Tampa), C. B. Markwardt (GSFC),
D. M. Palmer (LANL), T. Parsotan (GSFC),
T. Sakamoto (AGU) (i.e. the Swift-BAT team):
Using the data set from T-60 to T+243 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 240415A (trigger #1221874)
(Moss, et al., GCN Circ. 36108). The BAT ground-calculated position is
RA, Dec = 129.197, 73.150 deg which is
RA(J2000) = 08h 36m 47.2s
Dec(J2000) = +73d 09' 01.7"
with an uncertainty of 1.1 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 60%.
The mask-weighted light curve displays a bright pulse lasting for ~15 s and
peaking at ~T0+5 s and another dim pulse of emission at ~T0+30 s.
The T90 (15-350 keV) is 30.96 +- 3.59 sec (estimated error including systematics).
The time-averaged spectrum from T-0.70 to T+37.50 sec is best fit by a simple
power-law model. The power law index of the time-averaged spectrum is
2.28 +- 0.13. The fluence in the 15-150 keV band is 1.6 +- 0.1 x 10^-06 erg/cm2.
The 1-sec peak photon flux measured from T+5.09 sec in the 15-150 keV band
is 4.6 +- 0.4 ph/cm2/sec. All the quoted errors are at the 90% confidence
level.
The results of the batgrbproduct analysis are available at
https://swift.gsfc.nasa.gov/results/batgrbcat/BAT_refined_circular/1221874
GCN Circular 36136
Subject
GRB 240415A: Swift/UVOT Detection
Date
2024-04-16T13:38:30Z (a year ago)
From
Mike Siegel at PSU/Swift MOC <mhs18@psu.edu>
Via
Web form
M. H. Siegel (PSU) and M. J. Moss (GSFC)
report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 240415A
3309 s after the BAT trigger (Moss et al., GCN Circ. 36108). A source consistent
with the XRT position (Beardmore et al., GCN Circ. 36128) and the reported
optical transient (Pankov et al., GCN Circ. 36118, Moskvitin et al., GCN Circ. 36122,
Reguitti et al., GCN Circ. 36123