GRB 250201A
GCN Circular 39152
Subject
Konus-Wind detection of GRB 250201A
Date
2025-02-05T16:18:27Z (10 months ago)
From
Dmitry Frederiks at Ioffe Institute <fred@mail.ioffe.ru>
Via
email
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 250201A (Fermi-GBM detection: Fermi GBM team, GCN 39112;
BALROG localization: Preis & Greiner, GCN 39113;
INTEGRAL SPI/ACS detection: Barria et al., GCN 39117;
IPN triangulation: Kozyrev et al., GCN 39151)
triggered Konus-Wind (KW) at T0=35989.814 s UT (09:59:49.814).
The burst light curve shows a double-peaked emission pulse
with the total duration of ~21 s.
The emission is seen up to ~8 MeV.
The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB250201_T35989/
As observed by Konus-Wind, the burst had
a fluence of (1.21 ± 0.08)x10^-5 erg/cm^2 and
a 64-ms peak energy flux, measured from T0 + 12.160 s,
of (2.97 ± 0.34)x10^-6 erg/cm^2/s (both in the 20 keV - 10 MeV energy range).
The time-integrated spectrum (measured from T0 to T0+16.640 s)
is best fit in the 20 keV - 15 MeV range
by a GRB (Band) function with the following model parameters:
the low-energy photon index alpha = -0.72 (-0.12,+0.13),
the high energy photon index beta = -3.07 (-0.54,+0.27),
the peak energy Ep = 134 (-7,+8) keV,
chi2 = 118/97 dof.
The spectrum near the peak count rate (measured from T0+8.448 s to T0+16.640 s)
is best fit in the 20 keV - 15 MeV range
by a GRB (Band) function with the following model parameters:
the low-energy photon index alpha = -0.76 (-0.11,+0.13),
the high energy photon index beta = -2.95 (-0.34,+0.23),
the peak energy Ep = 138 (-8,+8) keV,
chi2 = 94/78 dof.
All the quoted errors are estimated at the 68% confidence level.
All the presented results are preliminary.
GCN Circular 39151
Subject
IPN triangulation of GRB 250201A
Date
2025-02-05T15:21:26Z (10 months ago)
From
Anna Ridnaia at Ioffe Institute <ridnaia@mail.ioffe.ru>
Via
Web form
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, A. Lysenko, D. Svinkin,
and T. Cline on behalf of the Konus-Wind team,
A. Goldstein, M. S. Briggs, C. Wilson-Hodge,
and E. Burns on behalf of the Fermi GBM 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 long-duration GRB 250201A
(Fermi-GBM detection: Fermi GBM team, GCN 39112;
BALROG localization: Preis & Greiner, GCN 39113;
INTEGRAL SPI/ACS detection: Barria et al., GCN 39117)
was detected by Fermi (GBM), Konus-Wind, INTEGRAL (SPI-ACS),
Swift (BAT), and Mars-Odyssey (HEND) at about 35987 s UT (09:59:47).
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:
115.287 -54.293
Corners:
137.464 -51.378
137.379 -51.074
93.570 -52.488
93.601 -52.814
-------------------------------
The error box area is 6.8 sq. deg, and its maximum
dimension is 26.3 deg (the minimum one is 21 arcmin).
The Sun distance was 101 deg.
A triangulation map and HEALPix FITS file are posted at
http://www.ioffe.ru/LEA/GRBs/GRB250201_T35989/IPN
The HEALPix triangulation map is the multi-order HEALPix in units of
probability density.
The Konus-Wind time history and spectrum will be given
in a forthcoming GCN Circular.
GCN Circular 39117
Subject
GRB 250201A: INTEGRAL SPI/ACS detection
Date
2025-02-01T19:34:25Z (10 months ago)
From
Aishwarya L Thakur at INAF-IAPS, Rome <aishth@outlook.com>
Via
Web form
Patrizia Barria(a,b), Giulia Gianfagna(a), James Craig Rodi(a), Aishwarya Linesh Thakur(a), Lorenzo Natalucci(a,b), Luigi Piro(a) report:
GRB 250201A was discovered by Fermi/GBM (GCN 39112) on 2025-02-01T09:59:46 (UTC). We searched for a corresponding counterpart in the INTEGRAL/SPI-ACS data.
In an SPI-ACS light curve above 80 keV, we find a signal temporally coincident with the GBM detection, having an approximate duration of ~ 20 sec. The signal consists of two pulses over this duration.
The approximate peak count rate in SPI-ACS is 77,500 cts/s for E>80 keV, over a median background rate of 62,800 cts/s.
This work is based on observations with INTEGRAL, an ESA project with instruments and a science data centre funded by ESA member states (especially the PI countries: Denmark, France, Germany, Italy, Switzerland, and Spain), and with the participation of Russia and the USA. The SPI-ACS detector system has been provided by MPE Garching/Germany.
-----
(a) INAF/IAPS-Rome
(b) ICSC National Research Centre for High-Performance Computing
GCN Circular 39113
Subject
GRB 250201A: BALROG localization (Fermi Trigger 760096791 / GRB 250201417)
Date
2025-02-01T10:53:32Z (10 months ago)
From
Jochen Greiner at MPE <jcgrog@mpe.mpg.de>
Via
email
T. Preis (University of Innsbruck) & J. Greiner (MPE Garching) report:
The public trigdat data of the Fermi Gamma-ray Burst Monitor (GBM) trigger
760096791 at 09:59:46 on 01 Feb. 2025 were automatically fitted for spectrum
and sky location with BALROG (Burgess et al. 2018, MNRAS 476, 1427;
Berlato et al. 2019, ApJ 873, 60).
The best-fit position is:
RA(2000.0) = 112.5 deg
Decl.(2000.0) = -54.7 deg
The 1 sigma statistical error radius is 2.0 deg.
We estimate an additional systematic error of 1 deg.
Further details are available at:
https://grb.mpe.mpg.de/grb/GRB250201417/
The Healpix map can be downloaded from:
https://grb.mpe.mpg.de/grb/GRB250201417/healpix
The location parameters are available as JSON at:
https://grb.mpe.mpg.de/grb/GRB250201417/json
GCN Circular 39112
Subject
GRB 250201A: Fermi GBM Final Real-time Localization
Date
2025-02-01T10:10:18Z (10 months ago)
From
Fermi GBM Team at MSFC/Fermi-GBM <do_not_reply@GIOC.nsstc.nasa.gov>
Via
email
The Fermi GBM team reports the detection of a likely LONG GRB
At 09:59:46 UT on 1 Feb 2025, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 250201A (trigger 760096791.667376 / 250201417).
The on-ground calculated location, using the Fermi GBM trigger data, is RA = 115.8, Dec = -52.6 (J2000 degrees, equivalent to J2000 07h 43m, -52d 36'), with a statistical uncertainty of 1.1 degrees.
The angle from the Fermi LAT boresight is 17.0 degrees.
The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250201417/quicklook/glg_skymap_all_bn250201417.png
The HEALPix FITS file, including the estimated localization systematic, can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250201417/quicklook/glg_healpix_all_bn250201417.fit
The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250201417/quicklook/glg_lc_medres34_bn250201417.gif