GRB 250204B
GCN Circular 39141
Subject
GRB 250204B: Fermi GBM Final Localization
Date
2025-02-04T14:58:59Z (4 months ago)
From
Marianna Dafčíková at Masaryk University <500025@mail.muni.cz>
Via
Web form
The Fermi GBM team reports the detection of a likely LONG GRB
At 06:41:14.00 UT on 04 February 2025, the Fermi Gamma-ray Burst Monitor (GBM)
triggered and located GRB 250204B (trigger 760344078/250204279).
The on-ground calculated location, using the Fermi GBM trigger data,
is RA = 2.35, Dec = 29.70 (J2000 degrees, equivalent to J2000 0h 9m, +29d 41'),
with a statistical uncertainty of 2.80 degrees.
The angle from the Fermi LAT boresight is 124 degrees.
The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250204279/quicklook/glg_skymap_all_bn250204279.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/bn250204279/quicklook/glg_healpix_all_bn250204279.fit
The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250204279/quicklook/glg_lc_medres34_bn250204279.gif
GCN Circular 39142
Subject
GRB 250204B: AstroSat CZTI detection of a short burst
Date
2025-02-04T16:30:31Z (4 months ago)
From
Gaurav Waratkar at IIT Bombay <gauravwaratkar@iitb.ac.in>
Via
Web form
A. Dasgupta (BITS Pilani, Hyderabad), 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) 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 250204B which was also detected by Fermi/GBM (Fermi-GBM Team, GCN Circ. 39141). Inspection of INTEGRAL/SPI-ACS data also showed the detection of the burst.
The source was clearly detected in the CZT detectors in the 20-200 keV energy range. The light curve peaks at 2025-02-04 06:41:14.050 UTC. The measured peak count rate associated with the burst is 446 (+149, -49) counts/s above the background in the combined data of two (out of four) quadrants, with a total of 237 (+60, -71) counts. The local mean background count rate was 116 (+6, -8) counts/s. Using cumulative rates, we measure a T90 of 1.1 (+0.3, -0.5) s.
It was also clearly detected in the CsI anticoincidence (Veto) detector in the 100-500 keV energy range. The light curve peaks at 2025-02-04 06:41:13.502 UTC. The measured peak count rate is 300 (+70, -41) counts/s above the background in the combined Veto data of all quadrants, with a total of 659 (+172, -189) counts. The local mean background count rate was 1265 (+8, -8) 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 39145
Subject
IPN triangulation of GRB 250204B (short/hard)
Date
2025-02-04T17:51:38Z (4 months ago)
From
Dmitry Svinkin at Ioffe Institute <svinkin@mail.ioffe.ru>
Via
Web form
D. Svinkin, D. Frederiks, A. Lysenko, A. Ridnaia,
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,
G. Waratkar, J.Joshi, V. Bhalerao, D. Bhattacharya,
and S. Vadawale, on behalf of the Astrosat-CZTI team, report:
The short-duration GRB 250204B
(Fermi-GBM detection: The Fermi GBM team, GCN 39141;
AstroSat-CZTI detection: Dasgupta et al., GCN 39142)
was detected by Fermi (GBM trigger 760344078), AstroSat (CZTI),
Swift (BAT), Konus-Wind, and INTEGRAL (SPI-ACS)
at about 24074 s UT (06:41:14).
We have triangulated it to a preliminary, 3 sigma error box
whose coordinates are:
---------------------------------------------
RA(2000), deg Dec(2000), deg
---------------------------------------------
Center:
1.945 (00h 07m 47s) +35.469 (+35d 28' 07")
Corners:
4.715 (00h 18m 52s) +29.985 (+29d 59' 08")
6.110 (00h 24m 26s) +29.936 (+29d 56' 11")
358.613 (23h 54m 27s) +40.986 (+40d 59' 08")
356.896 (23h 47m 35s) +41.060 (+41d 03' 34")
---------------------------------------------
The error box area is 13.4 sq. deg, and its maximum
dimension is 13.4 deg (the minimum one is 1 deg).
The Sun distance was 64 deg.
This localization may be improved.
The IPN localization is consistent with, but reduces the area of,
the Fermi-GBM localization (GCN 39141).
A triangulation map and HEALPix FITS file are posted at
http://www.ioffe.ru/LEA/GRBs/GRB250204_T24073/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 39163
Subject
GRB 250204B: SVOM/GRM observation of a likely short burst
Date
2025-02-06T06:08:28Z (4 months ago)
From
yqzhang_cl@163.com
Via
Web form
SVOM/GRM team: Yan-Qiu Zhang, Wen-Jun Tan, Chen-Wei Wang, Shi-Jie Zheng, Shao-Lin Xiong, Shuang-Nan Zhang (IHEP)
SVOM/ECLAIRs team: Nicolas Dagoneau(CEA), Maria-GraziaBernardini (INAF-OAB), Jean-Luc Atteia (IRAP)
report on behalf of the SVOM team:
SVOM/GRM was triggered in-flight by a likely short burst GRB 250204B (sb25020402) at 2025-02-04T06:41:14.100 UTC (T0), which was also observed by Fermi/GBM (Fermi GBM team, GCN #39141) and AstroSat CZTI (A. Dasgupta et al., GCN #39142).
With the event-by-event data downloaded through the X-band ground station, the GRM light curve shows that this burst consists of a single pulse with a T90 of 2.92 +/- 0.08 s in the 15-300 keV band.
In addition, the position of this burst, as determined by Fermi/GBM (GCN #39141, RA: 2.35 deg, DEC: 29.70 deg, Error: 2.80 deg), is located at about 137 degrees from the SVOM optical axis, and outside the ECLAIRs field of view.
The SVOM/GRM light curve can be found here:
https://www.bursthub.cn//admin/static/svgrb250204B.png
The Space Variable Objects Monitor (SVOM) is a China-France joint mission led by the Chinese National Space Administration (CNSA, China), National Center for Space Studies (CNES, France) and the Chinese Academy of Sciences (CAS, China), which is dedicated to observing gamma-ray bursts and other transient phenomena in the energetic universe. GRM is developed by the Institute of High Energy Physics (IHEP) of CAS.
The SVOM/GRM point of contact for this burst is: Yan-Qiu Zhang (IHEP) (zhangyanqiu@ihep.ac.cn)
GCN Circular 39205
Subject
Konus-Wind detection of GRB 250204B
Date
2025-02-07T15:46:33Z (4 months ago)
From
Anna Ridnaia at Ioffe Institute <ridnaia@mail.ioffe.ru>
Via
Web form
A. Ridnaia, D. Frederiks, A. Lysenko, D. Svinkin,
A. Tsvetkova, M. Ulanov, and T. Cline,
on behalf of the Konus-Wind team, report:
The short-duration GRB 250204B
(Fermi-GBM detection: Fermi GBM team, GCN 39141;
AstroSat CZTI detection: Dasgupta et al., GCN 39142;
IPN triangulation: Svinkin et al., GCN 39145;
SVOM/GRM observation: Zhang et al., GCN 39163)
triggered Konus-Wind at T0=24073.659 s UT (06:41:13.659).
The burst light curve shows a single pulse
which starts at ~T0-0.1 s and has a total duration of ~1.5 s.
The emission is seen up to ~2 MeV.
The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB250204_T24073/
As observed by Konus-Wind, the burst
had a fluence of 2.99(-0.29,+0.37)x10^-6 erg/cm2,
and a 16-ms peak flux, measured from T0+0.008 s,
of 7.51(-1.64,+1.74)x10^-6 erg/cm2/s
(both in the 20 keV - 10 MeV energy range).
The 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(-0.17,+0.19)
and Ep = 383(-66,+92) keV (chi2 = 16/22 dof).
Fitting by a GRB (Band) model yields the same alpha and Ep,
and an upper limit on the high energy photon index: beta < -2.1
(chi2 = 16/21 dof).
All the quoted errors are at the 68% confidence level.
All the quoted values are preliminary.
GCN Circular 39255
Subject
GRB 250204B: GRBAlpha detection
Date
2025-02-09T18:25:51Z (4 months ago)
From
Michaela Ďuríšková at Masaryk University <505876@mail.muni.cz>
Via
Web form
M. Duriskova, M. Dafcikova, J. Ripa, M. Kolar (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, L. Szakszonova, J.-P. Breuer, F. Hroch (Masaryk U.), T. Urbanec, M. Kasal, A. Povalac (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. Lipovsky (Technical U. of Kosice), G. Galgoczi (Wigner Research Center/Eotvos U.), Y. Uchida, H. Poon, H. Matake (Hiroshima U.), N. Uchida (ISAS/JAXA), T. Bozoki (Eotvos U.), G. Dalya (Eotvos U.), T. Enoto (Kyoto U.), Zs. Frei (Eotvos U.), G. Friss (Eotvos U.), Y. Fukazawa, K. Hirose (Hiroshima U.), S. Hisadomi (Nagoya U.), Y. Ichinohe (Rikkyo U.), K. Kapas (Eotvos U.), L. L. Kiss (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 likely long-duration GRB 250204B (Fermi/GBM detection: GCN 39141; AstroSat/CZTI detection: GCN 39142; SVOM/GRM detection: GCN 39163; Konus/Wind detection: GCN 39205; INTEGRAL/SPI-ACS peak detection at 2025-02-04 ~06:41:14 UTC) was observed by the GRBAlpha 1U CubeSat (Pal et al. 2023, A&A, 677, 40; https://ui.adsabs.harvard.edu/abs/2023A%26A...677A..40P/abstract).
The detection was confirmed at the peak time 2025-02-04 06:41:13.6 UTC. The T90 duration measured by GRBAlpha is 6.0 s and the overall significance during T90 reaches 9.1 sigma.
The light curve obtained by GRBAlpha is available here: https://grbalpha.konkoly.hu/static/share/GRB250204B_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 future CubeSat constellation (Werner et al. Proc. SPIE 2018). The detector of GRBAlpha consists of a 75 x 75 x 5 mm3 CsI scintillator read out by a SiPM array, covering the energy range from ~50 keV to ~1000 keV. To increase the duty cycle and the downlink rate, the upgrade of the on-board data acquisition software stack is in progress. The ground segment is also supported by the radio amateur community and it takes advantage of the SatNOGS network for increased data downlink volume.