Gamma-ray Burst 240123C

(All information courtesy of the instrument teams.)

Previous IAU Circulars

none

Results of Observations

GCN Circular #35627
A.S. Kozyrev, D.V. Golovin, M.L. Litvak, I.G. Mitrofanov, and A.B. Sanin on behalf of the HEND/Mars Odyssey team,
A. Ridnaia, D. Frederiks, D. Svinkin, A. Lysenko, and T. Cline on behalf of the Konus-Wind team,
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 on behalf of the GRS-Odyssey GRB team, report:
The short-duration GRB 240123C was detected by Konus-Wind, INTEGRAL (SPI-ACS), Swift (BAT), and Mars-Odyssey (HEND) at about 83553 s UT (23:12:33). 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:
  244.077 (16h 16m 19s) -58.857 (-58d 51' 25")
 Corners:
  240.883 (16h 03m 32s) -55.715 (-55d 42' 55")
  241.066 (16h 04m 16s) -56.037 (-56d 02' 14")
  248.066 (16h 32m 16s) -61.657 (-61d 39' 24")
  247.747 (16h 30m 59s) -61.386 (-61d 23' 11")
 ---------------------------------------------
```
The error box area is 1219 sq. arcmin, and its maximum dimension is 7.0 deg (the minimum one is 3 arcmin). The Sun distance was 58 deg.
This localization may be improved.
A triangulation map and HEALPix FITS file are posted at http://www.ioffe.ru/LEA/GRBs/GRB240123_T83553/IPN
The Konus-Wind time history and spectrum will be given in a forthcoming GCN Circular.
GCN Circular #35635
J. Joshi (IUCAA), G. Waratkar (IITB), A. Vibhute (IUCAA), V. Bhalerao (IITB), D. Bhattacharya (Ashoka University/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 CIFT framework (Sharma et al., 2021, JApA, 42, 73) showed the detection of a short-duration GRB 240123C which was also detected by Konus-Wind, INTEGRAL (SPI-ACS), Swift (BAT), and Mars-Odyssey (HEND) (A.S. Kozyre, GCN Circ. 35627).
The source was clearly detected in the CZT detectors in the 20-200 keV energy range. The light curve peaks at 2024-01-23 23:12:36.55 UTC. The measured peak count rate associated with the burst is 1936 (+240, -237) counts/s above the background in the combined data of all quadrants, with a total of 798 (+116, -73) counts. The local mean background count rate was 312 (+8, -15) counts/s. Using cumulative rates, we measure a T90 of 1.4 (+0.61, -0.38) s.
The source was also clearly detected in the CsI anticoincidence (Veto) detector in the 100-500 keV energy range. The light curve peaks at 2024-01-23 23:12:36.81 UTC. The measured peak count rate associated with the burst is 560 (+70, -77) counts/s above the background in the combined data of all quadrants, with a total of 1166 (+263, -284) counts. The local mean background count rate was 1288 (+11, -11) counts/s. Due to the intrinsic 1 s binning of veto data, we cannot reliably estimate a T90 from it.
CZTI is built by a TIFR-led consortium of institutes across India, including VSSC, URSC, IUCAA, SAC, and PRL. The Indian Space Research Organisation funded, managed, and facilitated the project.
CZTI GRB detections are reported regularly on the payload site at: http://astrosat.iucaa.in/czti/?q=grb
GCN Circular #35643
M. Dafcikova, J. Ripa (Masaryk U.), A. Pal (Konkoly Observatory), N. Werner= (Masaryk U.), M. Ohno, H. Takahashi (Hiroshima U.), L. Meszaros, B. Csak (= Konkoly Observatory), N. Husarikova, F. Munz , M. Topinka, M. Kolar, L. Sza= kszonova, J.-P. Breuer, F. Hroch (Masaryk U.), T. Urbanec, M. Kasal, A. Po= valac (Brno U. of Technology), J. Hudec, J. Kapus, M. Frajt (Spacemanic s.r= .o), R. Laszlo, M. Koleda (Needronix s.r.o), M. Smelko, P. Hanak, P. Lipovs= ky (Technical U. of Kosice), G. Galgoczi (Wigner Research Center/Eotvos U.)= , Y. Uchida, H. Poon, H. Matake (Hiroshima U.), N. Uchida (ISAS/JAXA), T. B= ozoki (Eotvos U.), G. Dalya (Eotvos U.), T. Enoto (Kyoto U.), Zs. Frei (Eot= vos U.), G. Friss (Eotvos U.), Y. Fukazawa, K. Hirose (Hiroshima U.), S. Hi= sadomi (Nagoya U.), Y. Ichinohe (Rikkyo U.), K. Kapas (Eotvos U.), L. L. Ki= ss (Konkoly Observatory), T. Mizuno (Hiroshima U.), K. Nakazawa (Nagoya U.= ), H. Odaka (Univ of Tokyo), J. Takatsy (Eotvos U.), K. Torigoe (Hiroshima = U.), N. Kogiso, M. Yoneyama (Osaka Metropolitan U.), M. Moritaki (U. Tokyo)= , T. Kano (U. Michigan) -- the GRBAlpha collaboration.
The short-duration GRB 240123C (AstroSat detection: GCN 35635; INTEGRAL/SPI= -ACS peak detection at 2024-01-23 ~23:12:37) was observed by the GRBAlpha 1= U CubeSat (Pal et al. 2023, A&A, 677, 40; arXiv:2302.10048).
The detection was confirmed at the peak time 2024-01-23 23:12:37 UTC. The T= 90 duration measured by GRBAlpha is 2 s and the overall significance during= T90 reaches 12 sigma.
The light curve obtained by GRBAlpha is available here: https://grbalpha.konkoly.hu/static/share/GRB240123C_GCN.pdf
All GRBAlpha detections are listed at: https://monoceros.physics.muni.cz/hea/GRBAlpha/
GRBAlpha, launched on 2021 March 22, is a demonstration mission for a futur= e CubeSat constellation (Werner et al. Proc. SPIE 2018). The detector of GR= BAlpha consists of a 75 x 75 x 5 mm3 CsI scintillator read out by a SiPM ar= ray, covering the energy range from ~50 keV to ~1000 keV. To increase the d= uty cycle and the downlink rate, the upgrade of the on-board data acquisiti= on software stack is in progress. The ground segment is also supported by t= he radio amateur community and it takes advantage of the SatNOGS network fo= r increased data downlink volume.=20
GCN Circular #35658
A. Lysenko, D. Frederiks, A. Ridnaia, D. Svinkin, A. Tsvetkova, M. Ulanov, and T. Cline on behalf of the Konus-Wind team, report:
The short-duration GRB 240123C (IPN triangulation: Ridnaia et al., GCN circ. 35627; AstroSat CZTI detection: Joshi et al., GCN circ. 35635; GRBAlpha detection: Dafcikova et al., GCN circ. 35643) triggered Konus-Wind at T0=83553.043 s UT (23:12:33.043).
The burst light curve shows a single-pulse structure which starts at ~T0-0.1 s and has a total duration of ~1.0 s. The emission is seen up to 1 MeV.
The Konus-Wind light curve of this GRB is available at http://www.ioffe.ru/LEA/GRBs/GRB240123_T83553/
As observed by Konus-Wind, the burst had a fluence of 2.91(-0.22,+0.23)x10^-6 erg/cm2, and a 16-ms peak flux, measured from T0+0.160s, of 1.17(-0.32,+0.33)x10^-5 erg/cm2/s (both in the 20 keV - 10 MeV energy range).
A time-averaged spectrum of the burst (measured from T0 to T0+0.256 s) is best fit in the 20 keV - 10 MeV range by a power law with exponential cutoff model: dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep) with alpha = 0.85(-0.40,+0.46) and Ep = 210(-17,+19) keV (chi2 = 24/38 dof). Fitting by a GRB (Band) model yields the close alpha and Ep, and an upper limit on the high energy photon index: beta < -2.8 (chi2 = 22/37 dof).
All the quoted errors are at the 90% confidence level. All the quoted values are preliminary.

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Jochen Greiner, last update: 02-Feb-2024 [Disclaimer]