GRB 220124A

V. Prasad (IUCAA), G. Waratkar (IITB), A. Suresh (IITB), A. Vibhute
(IUCAA), V. Bhalerao (IITB), D. Bhattacharya (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 ML pipeline (Abraham et al.,
2021, MNRAS, 504, 3084) and the CIFT framework (Sharma et al., 2021,
JApA, 42, 73) showed detection of a long GRB 220124A.

The source, consisting of three distinct bursts, was clearly detected in
the 20-200 keV energy range. The strongest peak is at 2022-01-24
03:39:19.00 UT. The measured peak count rate associated with the burst
is 441 (+16, -17) cts/s above the background in the combined data of
four quadrants, with a total of 25670 (+1334, -1297) cts. The local mean
background count rate was 496 (+1, -1) cts/s. Using cumulative rates, we
measure a T90 of 231 (+4, -5) s.

All three bursts from the source were also clearly detected in the CsI
anticoincidence (Veto) detector in the 100-500 keV energy range. The
strongest peak is at 2022-01-24 03:39:24.32 UT. The measured peak count
rate is 6829 (+76, -81) cts/s above the background in the combined Veto
data of four quadrants, with a total of 362309 (+6293, -4918) cts. The
local mean background count rate was 16030 (+5, -11) cts/s. We measure a
T90 of 231 (+38, -2) s from the cumulative Veto light curve. 

We note that the burst has not been localised, and we cannot rule out an
association with any SGRs. The ASIMOV tool
(http://astrosat-ssc.iucaa.in:8080/ASIMOV/ASIMOV [1]) indicates that
other active missions were covering different parts of the sky, hence
confirmed non-detections from other missions can help localise the
source by inferring earth-occulted regions.

CZTI GRB detections are reported regularly on the payload site at
http://astrosat.iucaa.in/czti/?q=grb [2]. CZTI is built by a TIFR-led
consortium of institutes across India, including VSSC, ISAC, IUCAA, SAC,
and PRL. The Indian Space Research Organisation funded, managed, and
facilitated the project. 

Links:
------
[1] http://astrosat-ssc.iucaa.in:8080/ASIMOV/ASIMOV
[2] http://astrosat.iucaa.in/czti/?q=grb

J. C. Liu, S. L. Xiong, S. Xiao, Y. Q. Zhang,  C. Cai, P. Zhang, 
C. Y. Li, S. L. Xie, X. Y. Zhao, Y. Huang, X. Y. Song,
C. Zheng,  Y. Zhao, Z. W. Guo, W. C. Xue, C. W. Wang, 
Q. B. Yi, B. X. Zhang,  W. X. Peng, R. Qiao, D. Y. Guo, X. B. Li, 
X. Ma, L. M. Song, P. Wang, J. Wang, Z. Zhang, S. J. Zheng, W. Chen, 
J. J. He, G. Y. Zhao, Y. Q. Du, H. Wu, J. Liang, Q. Luo, X. L. Zhang, 
H. M. Zhang, Z. H. An, M. Gao, K. Gong, B. Li, C. Li, J. H. Li, 
X. Q. Li, Y. G. Li, X. H. Liang, X. J. Liu, Y. Q. Liu, X. L. Sun, 
Y. L. Tuo, J. Z. Wang, X. Y. Wen, Y. B. Xu, Y. P. Xu, S. Yang, 
C. Y. Zhang, D. L. Zhang, Fan Zhang, Fei Zhang,
X. Zhou, F. J. Lu, S. N. Zhang (IHEP)
report on behalf of GECAM team:

During the commissioning phase, GECAM-B was triggered in-flight by a long burst, 
GRB 220124A, at 2022-01-24T03:37:38.200 UTC (denoted as T0)���
which was also observed by CALET/GBM(triggerID: 1327030648), 
AstroSAT/CZTI(GCN #31521
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GECAM alert data was downlinked to the ground through the short message
service of BeiDou Navigation Satellite System (BDS) within ~60 s after T0.

According to the BDS alert data, this burst mainly consists of multiple pulses
with a duration of about 240 s. 

The GECAM light curve could be found here:
http://twiki.ihep.ac.cn/pub/GECAM/GRBList/GRB220124ALC_.png.png

Using the automatic on-ground localization pipeline with the BDS alert data, 
GECAM-B localized this burst to the following position (J2000): 
Ra: 246.18 deg 
Dec: 42.29 deg
Err: 2.96 deg (1-sigma, statistical only)
The current systematic error of location is estimated to be several degrees 
which could be minimized by the ongoing calibration.

The GECAM preliminary location could be found here:  
http://twiki.ihep.ac.cn/pub/GECAM/GRBList/GRB_220124Aloc.png

Please note that all GECAM results here are preliminary. The final analysis
will be published in journal papers or GECAM online catalog.

Gravitational wave high-energy Electromagnetic Counterpart All-sky Monitor
(GECAM) mission consists of two small satellites (GECAM-A and GECAM-B) in
Low Earth Orbit (600 km, 29 deg), launched on Dec 10, 2020 (Beijing Time),
which was funded by the Chinese Academy of Sciences (CAS).

A.S. Kozyrev, D.V. Golovin, M.L. Litvak, I.G. Mitrofanov, and A.B. Sanin
on behalf of the HEND/Mars Odyssey team,

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

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

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

W. Boynton, C. Fellows, K. Harshman, H. Enos, R. Starr,
and A.S. Gardner on behalf of the GRS-Odyssey GRB team, report:

The long-duration GRB 220124A
(AstroSat-CZTI detection: Prasad et al., GCN Circ. 31521
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GECAM detection: Liu et al., GCN Circ. 31524
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 )
has been detected by AstroSat (CZTI), Konus-Wind, Swift (BAT),
INTEGRAL (SPI-ACS), Mars-Odyssey (HEND), CALET (CGBM),
and GECAM-B (GRD) ,so far, at about 13058 s UT (03:37:38).
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:
   241.945 (16h 07m 47s) +41.979 (+41d 58' 45")
  Corners:
   244.220 (16h 16m 53s) +42.801 (+42d 48' 02")
   239.771 (15h 59m 05s) +41.164 (+41d 09' 51")
   239.711 (15h 58m 51s) +41.082 (+41d 04' 54")
   244.155 (16h 16m 37s) +42.723 (+42d 43' 23")
  ---------------------------------------------
The error box area is 678 sq. arcmin, and its maximum
dimension is 3.8 deg (the minimum one is 3.1 arcmin).
The Sun distance was 84 deg.

This box may be improved.

A triangulation map is posted at
http://www.ioffe.ru/LEA/GRBs/GRB220124_T13059/IPN/

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

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

The long GRB 220124A (AstroSat-CZTI  detection: Prasad et al., GCN Circ. 31521
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GECAM detection: Liu et al., GCN 31524
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IPN localization: Kozyrev et al., GCN 31525
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 )
triggered Konus-Wind (KW) at T0=13059.043 s UT (03:37:39.043).

The burst light curve shows a series of bright, multi-peaked pulses,
which starts at ~T0-10 s and has a total duration of ~250 s.
The emission is seen up to ~10 MeV.

The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB220124_T13059/

As observed by Konus-Wind, the burst had
a fluence of (2.0 �� 0.2)x10^-4 erg/cm^2 and
a 64-ms peak energy flux, measured from T0 + 40.512 s,
of (6.0 �� 0.9)x10^-6 erg/cm^2/s (both in the 20 keV - 10 MeV energy range).

The time-integrated spectrum (measured from T0 to T0+242.432 s)
is best fit in the 20 keV - 15 MeV range
by the GRB (Band) function with the following model parameters:
the low-energy photon index alpha = -0.81 (-0.06,+0.07),
the high energy photon index beta = -2.64 (-0.36,+0.22),
the peak energy Ep = 262 (-18,+18) keV,
chi2 = 86/97 dof.

The spectrum near the peak count rate (measured from T0+39.168 s
to T0+44.544 s) is best fit in the 20 keV - 15 MeV range
by the GRB (Band) function with the following model parameters:
the low-energy photon index alpha = -0.75 (-0.09,+0.10),
the high energy photon index beta = -2.61 (-0.89,+0.31),
the peak energy Ep = 381 (-45,+53) keV,
chi2 = 109/91 dof.

All the quoted errors are estimated at the 90% confidence level.
All the presented results are preliminary.