GRB 221124A

S. Sugita, A. Yoshida, T. Sakamoto (AGU), Y. Kawakubo (LSU), 
K. Yamaoka (Nagoya U), S. Nakahira (RIKEN), 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), S. Ricciarini (U of Florence),
P. S. Marrocchesi (U of Siena),
and the CALET collaboration:

The long GRB 221124A (GECAM Trigger #79; IPN RAW Notice at
02:00:24.17 on 24 November) triggered the CALET Gamma-ray Burst
Monitor (CGBM) at 02:00:24.88 UTC on 24 November 2022
(http://cgbm.calet.jp/cgbm_trigger/flight/1353290389/index.html).
The burst signal was seen by all CGBM detectors.

The burst light curve shows a multi-peaked structure that starts 
at T-58 sec and ends at T+~350 sec. We are not able to obtain 
the duration because of the scheduled HV turn-off started just 
after the end of the emission. 

The ground-processed light curve is available at
http://cgbm.calet.jp/cgbm_trigger/ground/1353290389/

The CALET data used in this analysis are provided by
the Waseda CALET Operation Center located at Waseda University.

Aaron Tohuvavohu (U Toronto), Gayathri Raman (PSU), James DeLaunay
(UAlabama), Jamie A. Kennea (PSU) report:

Swift/BAT did not localize GRB 221124A onboard (T0:
2022-11-24T02:00:24 UTC, CALET trig 1353290389, GECAM trig 79).

The CALET and GECAM notices, distributed in near real-time, triggered
the Swift Mission Operations Center operated Gamma-ray Urgent Archiver
for Novel Opportunities (GUANO; Tohuvavohu et al. 2020, ApJ, 900, 1).

Upon trigger, GUANO sent a command to the Swift Burst Alert Telescope
(BAT) to save 200 seconds of BAT event-mode data from [-50,+150]
seconds around the time of the burst. All the requested event mode
data was delivered to the ground.

The BAT likelihood search, NITRATES (DeLaunay + Tohuvavohu,
arXiv:2111.01769
Loading...
 
 ), detects the burst with a sqrt(TS) of 8 in a 1.024 s
analysis time bin.

NITRATES results, independently, are ambiguous with respect to whether
this burst originates from in or outside the BAT FOV.
The GECAM localization places this burst outside the contemporaneous BAT FoV.

See Section 9.1 and Figures 10 and 17 in the NITRATES paper for brief
descriptions and interpretation of sqrt(TS), DeltaLLHPeak, and
DeltaLLHOut.

GUANO is a fully autonomous, extremely low latency, spacecraft
commanding pipeline designed for targeted recovery of BAT event mode
data around the times of compelling astrophysical events to enable
more sensitive GRB searches.

A live reporting of Swift/BAT event data recovered by GUANO can be
found at: https://www.swift.psu.edu/guano/

D. Svinkin, D. Frederiks, A. Ridnaia, A. Lysenko,
and T. Cline on behalf of the Konus-Wind team,

S. Xiao, S.-L. Xiong, X.-Q. Li, X.-Y. Wen, L.-M. Song, S.-J. Zheng,
W.-X. Peng, and F. Zhang on behalf of the GECAM team,

E. Bozzo and C. Ferrigno, on behalf of the INTEGRAL SPI-ACS GRB team,

and

S. Barthelmy, J. Cummings, H. Krimm, D. Palmer, and A. Tohuvavohu
on behalf of the Swift-BAT team, report:

The long-duration GRB 221124A
(CALET-CGBM detection: Sugita et al., GCN Circ. 32981
Loading...
 
 ;
Swift/BAT-GUANO detection: Tohuvavohu et al., GCN Circ. 32984
Loading...
 
 ;
GECAM-B detection: Huang et al., ATel 15777)
has been detected by CALET (CGBM), Konus-Wind, INTEGRAL (SPI-ACS),
GECAM-B (GRD), and Swift (BAT), so far,
at about 7224 s UT (02:00:24).
The burst was outside the coded field of view of the BAT.

We have triangulated it to a preliminary, error box
whose coordinates are:
  ---------------------------------------------
   RA(2000), deg                 Dec(2000), deg
  ---------------------------------------------
  Center:
   310.423 (20h 41m 42s) +34.999 (+34d 59' 56")
  Corners:
   317.972 (21h 11m 53s) +25.823 (+25d 49' 21")
   314.677 (20h 58m 42s) +33.947 (+33d 56' 49")
   299.731 (19h 58m 56s) +43.400 (+43d 24' 01")
   305.508 (20h 22m 02s) +36.238 (+36d 14' 17")
  ---------------------------------------------
The error box area is 50 sq. deg, and its maximum
dimension is 23 deg (the minimum one is 3.3 deg).
The Sun distance was about 84 deg.

This box may be improved.

A triangulation map and HEALPix FITS file are posted at
http://www.ioffe.ru/LEA/GRBs/GRB221124_T07224/IPN

The Konus-Wind time history and spectrum will be given in a forthcoming
GCN Circular.

D. Svinkin, D. Frederiks, M. Ulanov, A. Tsvetkova,
A. Lysenko, A. Ridnaia, and T. Cline
on behalf of the Konus-Wind team, report:

The long-duration GRB 221124A
(CALET-CGBM detection: Sugita et al., GCN Circ. 32981
Loading...
 
 ;
Swift/BAT-GUANO detection: Tohuvavohu et al., GCN Circ. 32984
Loading...
 
 ;
GECAM-B detection: Huang et al., ATel 15777)
triggered Konus-Wind at T0=7224.17 s UT (02:00:24.170).

The burst light curve shows a multipeaked structure
which starts at ~T0-64 s and has a total duration of ~425 s.
The emission is seen up to 5 MeV.

The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB221124_T07224/

As observed by Konus-Wind, the burst
had a fluence of 4.71(-0.98,+1.92)x10^-5 erg/cm2,
and a 64-ms peak flux, measured from T0-0.006 s,
of 2.17(-0.76,+0.82)x10^-6 erg/cm2/s
(both in the 20 keV - 10 MeV energy range).

The time-averaged spectrum of the burst
(measured from T0 to T0+360.704 s)
is best fit in the 20 keV - 5 MeV range
by the GRB (Band) model with the following parameters:
the low-energy photon index alpha = -0.80(-0.30,+0.38),
the high energy photon index beta = -2.96(-7.04,+0.70),
the peak energy Ep = 172(-35,+47) keV
(chi2 = 74/74 dof).

The spectrum near the maximum count rate
(measured from T0 to T0+8.448 s)
is best fit in the 20 keV - 2 MeV range
by a power law with exponential cutoff model:
dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep)
with  alpha = -0.70(-0.36,+0.45)
and Ep = 275(-59,+106) keV (chi2 = 47/60 dof).
Fitting by a GRB (Band) model yields the same alpha and Ep,
and an upper limit on the high energy photon index: beta < -2.4
(chi2 = 47/59 dof).

All the quoted errors are at the 90% confidence level.
All the quoted values are preliminary.