- GCN NOTICE
TITLE: GCN/FERMI NOTICE
NOTICE_DATE: Mon 17 Feb 25 23:55:11 UT
NOTICE_TYPE: Fermi-GBM Flight Position
RECORD_NUM: 49
TRIGGER_NUM: 761529286
GRB_RA: 104.533d {+06h 58m 08s} (J2000),
105.028d {+07h 00m 07s} (current),
103.546d {+06h 54m 11s} (1950)
GRB_DEC: +52.017d {+52d 01' 00"} (J2000),
+51.981d {+51d 58' 52"} (current),
+52.084d {+52d 05' 03"} (1950)
GRB_ERROR: 4.55 [deg radius, statistical plus systematic]
GRB_INTEN: 1915 [cnts/sec]
DATA_SIGNIF: 39.80 [sigma]
INTEG_TIME: 0.256 [sec]
GRB_DATE: 20723 TJD; 48 DOY; 25/02/17
GRB_TIME: 86081.80 SOD {23:54:41.80} UT
GRB_PHI: 221.00 [deg]
GRB_THETA: 120.00 [deg]
DATA_TIME_SCALE: 0.2560 [sec]
HARD_RATIO: 1.18
LOC_ALGORITHM: 3 (version number of)
MOST_LIKELY: 92% GRB
2nd_MOST_LIKELY: 5% Distant Particles
DETECTORS: 0,0,0, 0,0,0, 0,0,1, 0,0,1, 0,0,
SUN_POSTN: 331.69d {+22h 06m 44s} -11.62d {-11d 37' 05"}
SUN_DIST: 124.94 [deg] Sun_angle= -8.9 [hr] (East of Sun)
MOON_POSTN: 206.60d {+13h 46m 24s} -14.04d {-14d 02' 20"}
MOON_DIST: 108.12 [deg]
MOON_ILLUM: 75 [%]
GAL_COORDS: 164.52, 22.05 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS: 100.18, 29.09 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL: http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250217996/quicklook/glg_lc_medres34_bn250217996.gif
COMMENTS: Fermi-GBM Flight-calculated Coordinates.
COMMENTS: This trigger occurred at longitude,latitude = 26.95,-15.97 [deg].
COMMENTS: The LC_URL file will not be created until ~15 min after the trigger.
- GCN NOTICE
TITLE: GCN/FERMI NOTICE
NOTICE_DATE: Mon 17 Feb 25 23:55:29 UT
NOTICE_TYPE: Fermi-GBM Ground Position
RECORD_NUM: 59
TRIGGER_NUM: 761529286
GRB_RA: 119.130d {+07h 56m 31s} (J2000),
119.582d {+07h 58m 20s} (current),
118.228d {+07h 52m 55s} (1950)
GRB_DEC: +46.930d {+46d 55' 48"} (J2000),
+46.861d {+46d 51' 41"} (current),
+47.064d {+47d 03' 49"} (1950)
GRB_ERROR: 2.94 [deg radius, statistical only]
DATA_SIGNIF: 45.20 [sigma]
DATA_INTERVAL: 0.256 [sec]
GRB_DATE: 20723 TJD; 48 DOY; 25/02/17
GRB_TIME: 86081.80 SOD {23:54:41.80} UT
GRB_PHI: 211.00 [deg]
GRB_THETA: 114.00 [deg]
E_RANGE: 44.032 - 279.965 [keV]
LOC_ALGORITHM: 4173 (Gnd S/W Version number)
SUN_POSTN: 331.69d {+22h 06m 44s} -11.62d {-11d 37' 05"}
SUN_DIST: 135.59 [deg] Sun_angle= -9.9 [hr] (East of Sun)
MOON_POSTN: 206.60d {+13h 46m 25s} -14.04d {-14d 02' 24"}
MOON_DIST: 98.20 [deg]
MOON_ILLUM: 75 [%]
GAL_COORDS: 172.28, 30.22 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS: 111.64, 25.66 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL: http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250217996/quicklook/glg_lc_medres34_bn250217996.gif
POS_MAP_URL: http://gcn.gsfc.nasa.gov/notices_f/gbm_gnd_loc_map_761529286.fits
COMMENTS: Fermi-GBM Ground-calculated Coordinates.
COMMENTS: Bright hard burst in the GBM.
COMMENTS: This Notice was ground-generated -- not flight-generated.
COMMENTS: The LC_URL file will not be created/available until ~15 min after the trigger.
COMMENTS: The POS_MAP_URL file will not be created/available until ~1.5 min after the notice.
- GCN NOTICE
TITLE: GCN/FERMI NOTICE
NOTICE_DATE: Tue 18 Feb 25 00:04:01 UT
NOTICE_TYPE: Fermi-GBM Final Position
RECORD_NUM: 0
TRIGGER_NUM: 761529286
GRB_RA: 131.570d {+08h 46m 17s} (J2000),
131.959d {+08h 47m 50s} (current),
130.794d {+08h 43m 10s} (1950)
GRB_DEC: +32.880d {+32d 52' 48"} (J2000),
+32.787d {+32d 47' 12"} (current),
+33.063d {+33d 03' 48"} (1950)
GRB_ERROR: 5.50 [deg radius, statistical only]
GRB_DATE: 20723 TJD; 48 DOY; 25/02/17
GRB_TIME: 86081.80 SOD {23:54:41.80} UT
GRB_PHI: 201.00 [deg]
GRB_THETA: 100.00 [deg]
E_RANGE: 44.032 - 279.965 [keV]
LOC_ALGORITHM: 41731 (Gnd S/W Version number)
SUN_POSTN: 331.69d {+22h 06m 46s} -11.62d {-11d 36' 57"}
SUN_DIST: 152.15 [deg] Sun_angle= -10.7 [hr] (East of Sun)
MOON_POSTN: 206.67d {+13h 46m 40s} -14.07d {-14d 04' 11"}
MOON_DIST: 85.21 [deg]
MOON_ILLUM: 75 [%]
GAL_COORDS: 190.82, 37.34 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS: 125.12, 14.37 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL: http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250217996/quicklook/glg_lc_medres34_bn250217996.gif
LOC_URL: http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250217996/quicklook/glg_locplot_all_bn250217996.png
COMMENTS: Fermi-GBM Final Position.
COMMENTS: This Notice was ground-generated -- not flight-generated.
COMMENTS: The LC_URL file should be available by the time this FINAL notice is produced.
COMMENTS: This notice was generated completely by automated pipeline processing.
COMMENTS: This is likely a Short GRB.
- GCN Circular #39357
The Fermi GBM team reports the detection of a likely SHORT GRB
At 23:54:41 UT on 17 Feb 2025, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 250217C (trigger 761529286.801804 / 250217996).
The on-ground calculated location, using the Fermi GBM trigger data, is RA = 131.6, Dec = 32.9 (J2000 degrees, equivalent to J2000 08h 46m, 32d 53'), with a statistical uncertainty of 5.5 degrees.
The angle from the Fermi LAT boresight is 100.0 degrees.
The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250217996/quicklook/glg_skymap_all_bn250217996.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/bn250217996/quicklook/glg_healpix_all_bn250217996.fit
The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250217996/quicklook/glg_lc_medres34_bn250217996.gif
- GCN Circular #39358
V.Lipunov, E.Gorbovskoy, N.Tiurina, P.Balanutsa, , D.Vlasenko, I.Panchenko,
A.Kuznetsov, G.Antipov, A.Sankovich, A.Sosnovskij, Yu.Tselik, M.Gulyaev, Ya.Kechin,
V.Senik, A.Chasovnikov, K.Labsina, I. Gorbunov (Lomonosov MSU),
O.Gress, N.Budnev (ISU),
C.Francile, F. Podesta, R.Podesta, E. Gonzalez (Observatorio Astronomico Felix Aguilar (OAFA),
A. Tlatov, D. Dormidontov (Kislovodsk Solar Station of the Pulkovo Observatory),
A. Gabovich, V.Yurkov (Blagoveschensk Educational StateUniversity)
D.Buckley (SAAO),
R.Rebolo (The Instituto de Astrofisica de Canarias),
L.Carrasco, J.R.Valdes, V.Chavushyan, V.M.Patino Alvarez, J.Martinez,
A.R.Corella, L.H.Rodriguez (INAOE, Guillermo Haro Astrophysics Observatory)
MASTER-SAAO robotic telescope (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in South Africa (South African Astronomical Observatory) started inspect of the Fermi GRB 250217C ( Fermi GBM team, GCN 39357) errorbox 588 sec after notice time and 626 sec after trigger time at 2025-02-18 00:05:08 UT, with upper limit up to 18.5 mag. The observations began at zenith distance = 74 deg. The sun altitude is -42.9 deg.
The galactic latitude b = 38 deg., longitude l = 191 deg.
Real time updated cover map and OT discovered available here:
https://master.sai.msu.ru/site/master2/observ.php?id=2781342
We obtain a following upper limits.
Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment
_________|_____________________|_____________________|____________________________________|_____|_______|_______|________
657 | 2025-02-18 00:05:08 | MASTER-SAAO | (08h 45m 43.52s , +32d 50m 06.0s) | C | 60 | 17.9 |
717 | 2025-02-18 00:05:08 | MASTER-SAAO | (08h 45m 43.52s , +32d 50m 05.9s) | C | 180 | 18.5 | Coadd
736 | 2025-02-18 00:06:27 | MASTER-SAAO | (08h 45m 43.62s , +32d 50m 10.7s) | C | 60 | 17.6 |
815 | 2025-02-18 00:07:46 | MASTER-SAAO | (08h 45m 43.81s , +32d 50m 10.7s) | C | 60 | 17.5 |
894 | 2025-02-18 00:09:05 | MASTER-SAAO | (08h 45m 44.00s , +32d 50m 14.7s) | C | 60 | 17.6 |
Filter C is a clear (unfiltred) band.
The observation and reduction will continue.
The message may be cited.
- GCN Circular #39359
M. Tembhurnikar (IUCAA), 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 250217C which was also detected by Fermi (Fermi-GBM Team, GCN Circ. 39357).
The source was clearly detected in the CZT detectors in the 20-200 keV energy range. The light curve peaks at 2025-02-17 23:54:41.85 UTC. The measured peak count rate associated with the burst is 1090 (+213, -122) counts/s above the background in the combined data of three quadrants (out of four), with a total of 296 (+53, -56) counts. The local mean background count rate was 273 (+15, -18) counts/s. Using cumulative rates, we measure a T90 of 0.35 (+0.39, -0.09) s.
The source was also detected in the CsI anticoincidence (Veto) detector in the 100-500 keV energy range. The light curve peaks at 2025-02-17 23:54:41.14 UTC. The measured peak count rate associated with the burst is 358 (+63, -67) counts/s above the background in the combined data of all quadrants, with a total of 309 (+169, -171) counts. 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 #39365
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. 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,
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 bright, short-duration GRB 250217C
(Fermi-GBM detection: The Fermi GBM team, GCN 39357;
AstroSat-CZTI detection: Tembhurnikar et al., GCN 39359)
was detected by Fermi (GBM trigger 761529286), AstroSat (CZTI),
Konus-Wind, INTEGRAL (SPI-ACS), and Mars-Odyssey (HEND)
at about 86082 s UT (23:54:42).
We have triangulated it to a preliminary, 3 sigma error box
whose coordinates are:
---------------------------------------------
RA(2000), deg Dec(2000), deg
---------------------------------------------
Center:
122.164 (08h 08m 39s) +45.257 (+45d 15' 24")
Corners:
121.397 (08h 05m 35s) +45.429 (+45d 25' 44")
122.008 (08h 08m 02s) +45.505 (+45d 30' 17")
122.915 (08h 11m 40s) +45.069 (+45d 04' 08")
122.314 (08h 09m 15s) +45.007 (+45d 00' 27")
---------------------------------------------
The error box area is 818 sq. arcmin, and its maximum
dimension is 1.13 deg (the minimum one is 17.6 arcmin).
The Sun distance was 137 deg.
This localization may be improved.
The IPN localization is consistent with, but reduces the area of,
the Fermi-GBM (GCN 39357) localization.
A triangulation map and HEALPix FITS file are posted at
http://www.ioffe.ru/LEA/GRBs/GRB250217_T86086/IPN/
The HEALPix triangulation map is the multi-order HEALPix in units of
probability density.
Swift-XRT ToO has been submitted.
The Konus-Wind time history and spectrum will be given
in a forthcoming GCN Circular.
- GCN Circular #39367
Jacob Smith (UAH) reports on behalf of the Fermi Gamma-ray Burst Monitor Team:
At 23:54:41.80 UT on 17 February 2025, the Fermi Gamma-ray Burst Monitor (GBM)
triggered and located GRB 250217C (trigger 761529286/250217996).
which was also detected by AstroSat (M. Tembhurnikar, et al. 2025, GCN 39359) and IPN triangulation (A.S. Kozyrev, et al. 2025, GCN 39365).
The Fermi GBM on-ground location is consistent with the IPN triangulation.
The angle from the Fermi LAT boresight is 100 degrees.
The GBM light curve consists of a double emission episode with a duration (T90)
of about 0.35 s (50-300 keV). The time-averaged spectrum
from T0-0.06 to T0+0.38 s is best fit by
a Band function with Epeak = 85 +/- 13 keV,
alpha = -0.2 +/- 0.3, and beta = -1.83 +/- 0.04.
The event fluence (10-1000 keV) in this time interval is
(1.68 +/- 0.05)E-06 erg/cm^2. The 64-ms peak photon flux measured
starting from T0+0.0 s in the 10-1000 keV band is 62 +/- 3 ph/s/cm^2.
The spectral analysis results presented above are preliminary;
final results will be published in the GBM GRB Catalog:
https://heasarc.gsfc.nasa.gov/W3Browse/fermi/fermigbrst.html
For Fermi GBM data and info, please visit the official Fermi GBM Support Page:
https://fermi.gsfc.nasa.gov/ssc/data/access/gbm/
- GCN Circular #39368
P. A. Evans (U. Leicester) reports on behalf of the Swift team:
Swift has initiated a series of observations, tiled on the sky, of the
IPN GRB 250217C. Automated analysis of the XRT data will
be presented online at http://www.swift.ac.uk/xrt_products/TILED_GRB00133
Any uncatalogued X-ray sources detected in this analysis will be
reported on this website and via GCN COUNTERPART notices. The probability of finding
serendipitous sources, unrelated to the IPN event is high: any X-ray source
considered to be a probable afterglow candidate will be reported via a GCN Circular
after manual consideration.
Details of the XRT automated analysis methods are detailed in Evans et
al. (2007, A&A, 469, 379; 2009, MNRAS, 397, 1177 and 2014, ApJS, 210, 8).
This circular is an official product of the Swift-XRT team.
- GCN Circular #39369
SVOM/GRM team: Chen-Wei Wang, Shi-Jie Zheng, Shao-Lin Xiong, Yue Huang, Shuang-Nan Zhang (IHEP)
SVOM/ECLAIRs team: Frédéric Piron (LUPM), Nicolas Dagoneau (CEA), Maria-Grazia Bernardini (INAF-OAB), Jean-Luc Atteia, Sébastien Guillot (IRAP)
report on behalf of the SVOM team:
SVOM/GRM was triggered in-flight by a short burst GRB 250217C (sb25021704) at 2025-02-17T23:54:41.900 UTC (T0), which was also observed by Fermi/GBM (Fermi GBM team, GCN #39357), AstroSat (M. Tembhurnikar et al., GCN #39359), Konus-Wind, HEND/Mars and INTEGRAL SPI-ACS (A.S. Kozyrev et al., GCN #39365).
With the event-by-event data downloaded through the X-band ground station, the GRM light curve shows that this burst consists of multi-pulses with a T90 of about 0.42 +0.07/-0.22 seconds in the 15-5000 keV.
The time-averaged spectrum from T0-0.2 to T0+0.2 s could be fit by a Band function with alpha = -0.61 +/- 0.3, beta = -1.87 +/- 0.07 and Epeak = 77 +20/-11 keV. The event fluence (10-1000 keV) in this time interval is (1.40 +/- 0.71)E-06 erg/cm^2.
The SVOM/GRM light curve can be found here:
https://www.bursthub.cn//admin/static/svgrb250217C.png
In addition, the position of this burst, as determined by Fermi/GBM (Fermi GBM Team, GCN #39357), is located at about 50 degrees from the SVOM optical axis, right at the edge of the ECLAIRs field of view.
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: Chen-Wei Wang (IHEP) (cwwang@ihep.ac.cn)
- GCN Circular #39370
Rosa L. Becerra (U Roma), Alan M. Watson (UNAM), Simone Dichiara (Penn State University), Eleonora Troja (U Roma), Camila Angulo Valdez (UNAM), Nat Butler (ASU), Tsvetelina Dimitrova (ASU), Alexander Kutyrev (GSFC/UMD), William H. Lee (UNAM), Océlotl López (UNAM), and Margarita Pereyra (UNAM) report:
We observed the field of GRB 250217C detected by Fermi/GBM (Fermi GBM Team et al., GCN 39357), AstroSat CZTI (Tembhurnikar et al., GCN 39359), and IPN (Kozyrev et al., GCN 39365), with the DDOTI/OAN wide-field imager at the Observatorio Astronomico Nacional on Sierra San Pedro Martir (http://ddoti.astroscu.unam.mx) on the night of 2025-02-19 UTC.
DDOTI observed the whole IPN error box reported by Kozyrev et al. (GCN 39365) from 03:31 UTC to 04:37 UTC (from T+27.6 to T+28.7 hours after the event) with a total exposure of 48 minutes, down to a 5-sigma limiting magnitude of w = 21.1.
Comparing our observations to the USNO-B1 and PanSTARRS PS1 DR2 catalogues, we
detect no uncatalogued sources within the observed field to our 5-sigma limit.
We thank the staff of the Observatorio Astronómico Nacional in San Pedro
Mártir.
- GCN Circular #39371
Alan M. Watson (UNAM), Antonio de Ugarte Postigo (LAM), Eleonora Troja (U Roma), Rosa L. Becerra (U Roma), Simone Dichiara (PSU), Stéphane Basa (UAR Pytheas), William H. Lee (UNAM), Dalya Akl (AUS), Camila Angulo (UNAM), Sarah Antier (OCA), Jean-Luc Atteia (IRAP), Nathaniel R. Butler (ASU), Damien Dornic (CPPM), Jean-Grégoire Ducoin (CPPM), Francis Fortin (IRAP), Noémie Globus (UNAM), Kin Ocelotl López (UNAM), Francesco Magnani (CPPM), Margarita Pereyra (UNAM), Ny Avo Rakotondrainibe (LAM), and Benjamin Schneider (LAM) report:
We imaged the IPN 3-sigma error box of GRB 250217C (Fermi GBM Team, GCN Circ. 39357, Tembhurnikar et al., GCN Circ. 39359, Kozyrev et al., GCN Circ. 39365) with the DDRAGO wide-field imager on the COLIBRÍ telescope at the Observatorio Astronómico Nacional on the Sierra de San Pedro Mártir in Mexico.
We used three pointings that, combined with the 26 arcmin field of COLIBRÍ/DDRAGO, cover more than 95% of the IPN error box.
We observed from 2025-02-19 02:51 to 04:18 UTC (27.0 to 28.4 hours after the trigger) and obtained 20 minutes of exposure at each pointing in the i filter. The data were coadded with custom software and analyzed in STDWeb/STDPipe (Karpov 2021), with photometric calibration against Pan-STARRS DR1 and image subtraction against Pan-STARRS DR2. Our photometry is not corrected for Galactic extinction.
We do not detect any likely optical counterpart to a 5-sigma limit of
i > 22.7
Our non-detections are consistent with the shallower limits reported by Becerra et al. (GCN Circ. 39370) and with the lack of a bright X-ray candidate counterpart in the tiled Swift/XRT ToO observations reported by Evans et al. (GCN Circ. 39368).
We warmly thank the COLIBRÍ and DDRAGO engineering teams and the staff of the Observatorio Astronómico Nacional on the Sierra de San Pedro Mártir.
- GCN Circular #39373
A.P. Beardmore (U. Leicester), V. D'Elia (SSDC & INAF-OAR), B.
Sbarufatti (INAF-OAB), C. Salvaggio (INAF-OAB), J.A. Kennea (PSU), D.N.
Burrows (PSU), M. A. Williams (PSU), J.P. Osborne (U. Leicester) and
P.A. Evans (U. Leicester) reports on behalf of the Swift-XRT team:
Swift-XRT has performed follow-up observations of the IPN-detected
burst GRB 250217C in a series of observations tiled on the sky. The
total exposure time is 3.5 ks, distributed over 7 tiles; the maximum
exposure at a single sky location in the tiling was 1.2 ks. The data
were collected between T0+69.9 ks and T0+98.0 ks, and are entirely in
Photon Counting (PC) mode.
No uncatalogued X-ray sources have been detected. The 3-sigma upper
limit in the field (not including the regions where the tiles overlap)
ranges from ~0.01 to ~0.03 ct s^-1, corresponding to a 0.3-10 keV
observed flux of 5.3e-13 to 1.3e-12 erg cm^-2 s^-1 (assuming a typical
GRB spectrum).
Three previously-catalogued X-ray sources have been detected, however
their status as catalogued objects makes them unlikely to be the
afterglow.
The results of the XRT-team automatic analysis of the tiled XRT
observations, including a position-specific upper limit calculator, are
available at https://www.swift.ac.uk/xrt_products/TILED_GRB00133.
This circular is an official product of the Swift-XRT team.
- GCN Circular #39386
D. Svinkin, D. Frederiks, A. Lysenko, A. Ridnaia,
A. Tsvetkova, M. Ulanov, and T. Cline
on behalf of the Konus-Wind team, report:
The short-duration GRB 250217C
(Fermi-GBM detection: The Fermi GBM team, GCN 39357;
Smith, GCN 39367;
AstroSat-CZTI detection: Tembhurnikar et al., GCN 39359;
IPN triangulation: Kozyrev et al., GCN 39365;
SVOM-GRM detection: Wang et al., GCN 39369)
triggered Konus-Wind at T0=86086.280 s UT (23:54:46.280).
The burst light curve shows a multipeaked structure
which starts at ~T0 and has a total duration of ~0.3 s.
The emission is seen up to ~4 MeV.
The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB250217_T86086/
As observed by Konus-Wind, the burst
had a fluence of 2.76(-0.35,+0.38)x10^-6 erg/cm2,
and a 16-ms peak flux, measured from T0+0.190 s,
of 2.38(-0.47,+0.49)x10^-5 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 - 4 MeV range
by the GRB (Band) model with the following parameters:
the low-energy photon index alpha = -0.27(-0.49,+0.70),
the high energy photon index beta = -1.93(-0.11,+0.09),
the peak energy Ep = 116(-26,+40) keV
(chi2 = 47/37 dof).
All the quoted errors are at the 68% confidence level.
All the quoted values are preliminary.
Previous IAU Circulars 
