TITLE: GCN CIRCULAR
NUMBER: 35660
SUBJECT: GRB 230812B: Update on Bad Time Intervals for Fermi GBM data
DATE: 24/02/02 20:44:59 GMT
FROM: Oliver J Roberts at USRA/NASA <oliver.roberts(a)nasa.gov>
O.J. Roberts (USRA) and W. Cleveland (USRA) report on behalf of the Fermi GBM Team:
"The Fermi Gamma-ray Burst Monitor data for GRB 230812B had a bad time interval affecting all data types and all detectors, which was reported in GCN #34694. Subsequently, we reprocessed the TTE data in an effort to remove spurious artefacts, such as the artificially created pulse centered at roughly T0+1.233 seconds due to TTE drop out. We encourage those in the community interested in analyzing this event, to use the v4 TTE trigger data found on the GBM HEASARC page: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230812790/…
We note, that while we have tried to reprocess the data for this trigger to the best of our ability, pulse pile-up and deadtime effects still remain in all detectors and data types from roughly T0+0.5 to T0+1.4 seconds. We again, recommend the exclusion of these time intervals for GBM analysis of this burst, as well as caution using bins adjacent to these selections."
View this GCN Circular online at https://gcn.nasa.gov/circulars/35660.
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TITLE: GCN CIRCULAR
NUMBER: 35659
SUBJECT: Konus-Wind detection of GRB 240124B
DATE: 24/02/02 15:58:30 GMT
FROM: Alexandra Lysenko at Ioffe Institute <alexandra.lysenko(a)mail.ioffe.ru>
A. Lysenko, D. Frederiks, A. Ridnaia, D. Svinkin, A. Tsvetkova, M. Ulanov,
and T. Cline on behalf of the Konus-Wind team, report:
The long-duration GRB 240124B
(AstroSat CZTI detection: Joshi et al., GCN 35636;
IPN triangulation: Ridnaia et al., GCN 35657)
triggered Konus-Wind at T0=76473.999 s UT (21:14:33.999).
The burst light curve shows a single-pulse structure
which starts at ~T0-1.1 s and has a total duration of ~4.0 s.
The emission is seen up to 3 MeV.
The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB240124_T76473/
As observed by Konus-Wind, the burst
had a fluence of 4.57(-0.85,+2.93)x10^-6 erg/cm2,
and a 64-ms peak flux, measured from T0+0.228s,
of 4.33(-1.37,+3.93)x10^-6 erg/cm2/s
(both in the 20 keV - 10 MeV energy range).
A time-averaged spectrum of the burst
(measured from T0 to T0+8.448 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 = -1.40(-0.35,+0.44)
and Ep = 270(-94,+1040) keV (chi2 = 113/97 dof).
Fitting by a GRB (Band) model yields close alpha and Ep,
and an upper limit on the high energy photon index: beta < -1.9
(chi2 = 112/96 dof).
All the quoted errors are at the 90% confidence level.
All the quoted values are preliminary.
View this GCN Circular online at https://gcn.nasa.gov/circulars/35659.
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TITLE: GCN CIRCULAR
NUMBER: 35658
SUBJECT: Konus-Wind detection of GRB 240123C
DATE: 24/02/02 15:53:58 GMT
FROM: Alexandra Lysenko at Ioffe Institute <alexandra.lysenko(a)mail.ioffe.ru>
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.
View this GCN Circular online at https://gcn.nasa.gov/circulars/35658.
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TITLE: GCN CIRCULAR
NUMBER: 35657
SUBJECT: IPN triangulation of GRB 240124B
DATE: 24/02/02 14:26:58 GMT
FROM: Anna Ridnaia at Ioffe Institute <ridnaia(a)mail.ioffe.ru>
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
G. Waratkar (IITB), J.Joshi (IUCAA), A. Vibhute (IUCAA),
V. Bhalerao (IITB), D. Bhattacharya (Ashoka University/IUCAA),
A. R. Rao (IUCAA/TIFR), and S. Vadawale (PRL)
on behalf of the Astrosat-CZTI team,
report:
The long-duration GRB 240124B
(AstroSat CZTI detection: Joshi et al., GCN 35636)
was detected by Konus-Wind, INTEGRAL (SPI-ACS),
Swift (BAT), and AstroSat (CZTI)
at about 76474 s UT (21:14:34).
The burst was outside the coded field of view of the BAT.
We have triangulated this GRB to the following annuli:
---------------------------------------------------
annulus R.A. Dec. R dR (3sigma)
(deg) (deg) (deg) (deg)
---------------------------------------------------
Konus-SPI-ACS 114.536 21.719 79.082 2.281
Konus-BAT 112.129 19.162 79.550 1.622
---------------------------------------------------
The annuli combined with the KW ecliptic latitude response
give 254.7 sq.deg (3 sigma) localization region.
A triangulation map and HEALPix FITS file are posted at
http://www.ioffe.ru/LEA/GRBs/GRB240124_T76473/IPN
The Konus-Wind time history and spectrum will be given
in a forthcoming GCN Circular.
View this GCN Circular online at https://gcn.nasa.gov/circulars/35657.
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TITLE: GCN CIRCULAR
NUMBER: 35656
SUBJECT: GRB 240201A: AstroSat CZTI detection
DATE: 24/02/02 13:14:15 GMT
FROM: Gaurav Waratkar at IIT Bombay <gauravwaratkar24(a)gmail.com>
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 long-duration GRB 240201A. Inspection of Integral SPI-ACS data also shows a detection of the burst.
The source was clearly detected in the CZT detectors in the 20-200 keV energy range. The light curve showed multiple peaks of emission with the strongest peak at 2024-02-01 18:33:32.50 UTC. The measured peak count rate associated with the burst is 205 (+39, -36) counts/s above the background in the combined data of all quadrants, with a total of 832 (+230, -175) counts. The local mean background count rate was 313 (+3, -5) counts/s. Using cumulative rates, we measure a T90 of 10 (+3, -4) s.
The source was also clearly detected in the CsI anticoincidence (Veto) detector in the 100-500 keV energy range. The light curve showed multiple peaks of emission with the strongest peak at 2024-02-01 18:33:32.47 UTC. The measured peak count rate associated with the burst is 335 (+68, -55) counts/s above the background in the combined data of all quadrants, with a total of 2054 (+352, -383) counts. The local mean background count rate was 1480 (+6, -7) counts/s. We measure a T90 of 11 (+3, -2) s from the cumulative Veto light curve.
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
View this GCN Circular online at https://gcn.nasa.gov/circulars/35656.
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