GRB 211124A

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

Swift/BAT did not successfully trigger on GRB 211124A (T0:
2021-11-24T02:29:53.5 UTC, Fermi/GBM #659413798).

The Fermi/GBM notice, 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 by this notice, 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
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 ), detects the burst with a sqrt(TS) of 10.4 in a
0.512 s analysis time bin.
The estimated T90 in the detector is 0.4 +/- 0.2 s (15-350 keV).

NITRATES results are consistent with a burst coming from outside the
coded FOV, with DeltaLLHOut of 5.
An out of FOV origin is consistent with the Fermi/GBM localization.

See Section 9.1 and Figure 20 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, S. Golenetskii, D. Frederiks, A. Ridnaia,
A. Lysenko, and T. Cline on behalf of the Konus-Wind team,

K. Hurley, on behalf of the IPN,

A. von Kienlin, X. Zhang, A. Rau, V. Savchenko, E. Bozzo,
and C. Ferrigno, on behalf of the INTEGRAL SPI-ACS GRB team,

A. Goldstein, M. S. Briggs, and C. Wilson-Hodge
on behalf of the Fermi GBM team,

and

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

The short-duration GRB 211124A
(Swift/BAT-GUANO detection: DeLaunay et al., GCN Circ. 31113
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 )
has been detected by Fermi (GBM trigger 659413798),
Swift (BAT), INTEGRAL (SPI-ACS), and Konus-Wind in the waiting mode,
so far, at about 8994 s UT (02:29:54).
The burst was outside the coded field of view of the BAT.

We have triangulated it to a preliminary, 3 sigma error box
whose coordinates are:
  ----------------------------------
   RA(2000), deg    Dec(2000), deg
  ----------------------------------
  Center:
   85.2              -59.2
  Corners:
   22.5              -32.8
   18.6              -46.6
   85.9              -76.2
  129.3              -71.6
  ----------------------------------
The error box area is about 736 sq. deg, and its maximum
dimension is 64 deg (the minimum one is 12.5 deg).
The Sun distance was about 96 deg.

This box may be improved.

The IPN localization is consistent with, but reduces the area of, the
Fermi final position and BALROG 
(https://grb.mpe.mpg.de/grb/GRB211124104/) localizations.

A triangulation map and HEALPix FITS file are posted at
http://www.ioffe.ru/LEA/GRBs/GRB211124_T08993/IPN

Boyan A. Hristov (UAH) reports on behalf of the Fermi GBM Team:

"At 02:29:53.56 UT on 24 November 2021, the Fermi Gamma-Ray Burst
Monitor (GBM) triggered and located GRB 211124A (trigger 659413798
/ 211124104),

The results from Swift/BAT + NITRATES (DeLaunay et al. 2021, GCN 31113
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 )
are consistent with a burst coming from out of the FOV,
which is also consistent with the GBM in-flight location.

The GBM location, using the GBM trigger data, is RA = 94.967,
DEC = -61.433 (J2000 degrees, equivalent to 06h 20m, -61d 26'), with a
statistical uncertainty of 5.98 degrees (radius, 1-sigma containment,
statistical only; there is additionally a systematic error which we
have characterized as a core-plus-tail model, with 90% of GRBs having
a 3.7 deg error and a small tail suffering a larger than 10 deg
systematic error. [Connaughton et al. 2015, ApJS, 216, 32] ).

The angle from the Fermi LAT boresight at the GBM trigger time is
45.00 degrees.

The GBM light curve shows two peaks with a duration (T90) of about
0.5 s (50-300 keV).  The time-averaged spectrum from T0-0.128 s to
T0+0.576 s is well fit by a power law function with an exponential
high-energy cutoff.  The power law index is -0.65 +/- 0.16 and the
cutoff energy, parameterized as Epeak, is 357.50 +/- 80.10 keV.
The event fluence (10-1000 keV) in this time interval is
(1.004 +/- 0.120)E-06 erg/cm^2. The 64-ms peak photon flux measured
starting from T0 s in the 10-1000 keV band is 27 +/- 3 ph/s/cm^2.

The spectral analysis results presented above are preliminary;
final results will be published in the GBM GRB Catalog:
https://heasarc.gsfc.nasa.gov/W3Browse/fermi/fermigbrst.html

For Fermi GBM data and info, please visit the official Fermi GBM Support Page:
https://fermi.gsfc.nasa.gov/ssc/data/access/gbm/"