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GRB 251117A

GCN Circular 42768

Subject

GRB 251117A: Swift-XRT observations

Date

2025-11-19T18:06:28Z (a month ago)

From

Phil Evans at U of Leicester <pae9@star.le.ac.uk>

Via

J.A. Kennea (PSU), A.P. Beardmore (U. Leicester), J.P. Osborne (U.
Leicester), P. D'Avanzo (INAF-OAB), M.G. Bernardini (INAF-OAB), E.
Ambrosi  (INAF-IASFPA) , D.N. Burrows (PSU), S. Lanava (PSU) and P.A.
Evans (U. Leicester) reports on behalf of the Swift-XRT team:

Swift-XRT has performed follow-up observations of the
Fermi/GBM-detected burst GRB 251117A in a series of observations tiled
on the sky.  The total exposure time is  6.5 ks, distributed over 7
tiles; the maximum exposure at a single sky location in the tiling was
2.0 ks. The data were collected between T0+48.9 ks and T0+81.8 ks, and
are entirely in Photon Counting (PC) mode. 

Thirteen uncatalogued X-ray sources have been detected, however none of
them is above the RASS limit or shows definitive signs of fading.
Therefore, at the present time we cannot identify which, if any, is the
afterglow. Details of these sources are given below:

Source 1:
  RA (J2000.0):  331.2065  =  22h 04m 49.57s
  Dec (J2000.0): +5.5085  =  +05d 30' 30.6"
  Error: 8.0 arcsec (radius, 90% conf.)
  Count-rate: (7.5 [+4.2, -3.1])e-3 ct s^-1   
  Distance: 401 arcsec from Fermi/GBM position.
  Flux: (2.8 [+1.5, -1.1])e-13 erg cm^-2 s^-1 (observed, 0.3-10 keV)

Source 2:
  RA (J2000.0):  331.2121  =  22h 04m 50.90s
  Dec (J2000.0): +5.6862  =  +05d 41' 10.4"
  Error: 18.7 arcsec (radius, 90% conf.)
  Count-rate: (4.4 [+2.7, -1.9])e-3 ct s^-1   
  Distance: 523 arcsec from Fermi/GBM position.

Source 3:
  RA (J2000.0):  331.1150  =  22h 04m 27.61s
  Dec (J2000.0): +5.1842  =  +05d 11' 03.0"
  Error: 8.5 arcsec (radius, 90% conf.)
  Count-rate: (7.0 [+4.5, -3.2])e-3 ct s^-1   
  Distance: 1539 arcsec from Fermi/GBM position.

Source 6:
  RA (J2000.0):  331.1130  =  22h 04m 27.12s
  Dec (J2000.0): +5.7560  =  +05d 45' 21.6"
  Error: 7.8 arcsec (radius, 90% conf.)
  Count-rate: (8.2 [+4.5, -3.4])e-3 ct s^-1   
  Distance: 947 arcsec from Fermi/GBM position.
  Flux: (2.8 [+1.5, -1.2])e-13 erg cm^-2 s^-1 (observed, 0.3-10 keV)

Source 7:
  RA (J2000.0):  331.5308  =  22h 06m 07.38s
  Dec (J2000.0): +5.4134  =  +05d 24' 48.2"
  Error: 6.5 arcsec (radius, 90% conf.)
  Count-rate: (4.9 [+2.6, -1.9])e-3 ct s^-1   
  Distance: 1000 arcsec from Fermi/GBM position.

Source 8:
  RA (J2000.0):  331.7897  =  22h 07m 09.54s
  Dec (J2000.0): +5.6746  =  +05d 40' 28.6"
  Error: 7.8 arcsec (radius, 90% conf.)
  Count-rate: (7.1 [+4.4, -3.1])e-3 ct s^-1   
  Distance: 1794 arcsec from Fermi/GBM position.

Source 9:
  RA (J2000.0):  330.9021  =  22h 03m 36.49s
  Dec (J2000.0): +5.4483  =  +05d 26' 54.0"
  Error: 8.3 arcsec (radius, 90% conf.)
  Count-rate: (7.3 [+4.4, -3.3])e-3 ct s^-1   
  Distance: 1491 arcsec from Fermi/GBM position.
  Flux: (3.5 [+2.1, -1.6])e-13 erg cm^-2 s^-1 (observed, 0.3-10 keV)

Source 10:
  RA (J2000.0):  331.7481  =  22h 06m 59.54s
  Dec (J2000.0): +5.3975  =  +05d 23' 51.1"
  Error: 8.5 arcsec (radius, 90% conf.)
  Count-rate: 0.0109 [+0.0053, -0.0040] ct s^-1   
  Distance: 1721 arcsec from Fermi/GBM position.

Source 11:
  RA (J2000.0):  330.8986  =  22h 03m 35.66s
  Dec (J2000.0): +5.4101  =  +05d 24' 36.5"
  Error: 8.6 arcsec (radius, 90% conf.)
  Count-rate: (8.4 [+4.7, -3.5])e-3 ct s^-1   
  Distance: 1549 arcsec from Fermi/GBM position.

Source 12:
  RA (J2000.0):  330.9379  =  22h 03m 45.11s
  Dec (J2000.0): +5.3847  =  +05d 23' 05.0"
  Error: 7.1 arcsec (radius, 90% conf.)
  Count-rate: (9.1 [+4.8, -3.5])e-3 ct s^-1   
  Distance: 1458 arcsec from Fermi/GBM position.

Source 13:
  RA (J2000.0):  330.8498  =  22h 03m 23.95s
  Dec (J2000.0): +5.4122  =  +05d 24' 44.0"
  Error: 9.1 arcsec (radius, 90% conf.)
  Count-rate: (5.8 [+4.2, -2.8])e-3 ct s^-1   
  Distance: 1710 arcsec from Fermi/GBM position.

Source 14:
  RA (J2000.0):  330.7987  =  22h 03m 11.70s
  Dec (J2000.0): +5.6452  =  +05d 38' 42.7"
  Error: 9.8 arcsec (radius, 90% conf.)
  Count-rate: (6.7 [+4.2, -3.0])e-3 ct s^-1   
  Distance: 1816 arcsec from Fermi/GBM position.

Source 15:
  RA (J2000.0):  330.9250  =  22h 03m 42.01s
  Dec (J2000.0): +5.4456  =  +05d 26' 44.0"
  Error: 32.4 arcsec (radius, 90% conf.)
  Count-rate: (5.7 [+4.1, -3.1])e-3 ct s^-1   
  Distance: 1416 arcsec from Fermi/GBM position.
  Flux: (1.79 [+1.29, -0.96])e-12 erg cm^-2 s^-1 (observed, 0.3-10 keV)

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_GRB00141.

This circular is an official product of the Swift-XRT team.

GCN Circular 42762

Subject

GRB 251117A: Insight-HXMT/HE detection

Date

2025-11-19T15:10:34Z (a month ago)

From

Yue Wang <m18509381757@163.com>

Via

Web form

Yue Wang, Chen-Wei Wang, Chao Zheng, and Shao-Lin Xiong (IHEP) report on behalf of the Insight-HXMT team:

At 2025-11-17T12:19:52.500 (T0), Insight-HXMT/HE detected a short-duration GRB 251117A, which is also detected by Fermi/GBM (Fermi GBM Team, GCN #42719Loading...
 
 ), Fermi/LAT (A. Holzmann Airasca et. al., GCN #42729Loading...
 
 ) and SVOM/GRM (Yue Wang et. al., GCN #42731Loading...
 
 ).

The Insight-HXMT/HE light curve mainly consists of multiple peaks with a T90 of 2.3 +2.2/-1.1 s. The 1s peak rate, measured from T0-0.05 s, is 1167 cnts/sec. Insight-HXMT/HE detected a total of 1604 counts from this burst.

The Insight-HXMT/HE light curve can be found here:
https://www.bursthub.cn//admin/static/hxmtgrb251117A.png

All measurements above are made with the CsI detectors of Insight-HXMT/HE operating in the regular mode with the energy range of about 60-900 keV (deposited energy). Only gamma-rays with energy greater than about 200 keV can penetrate the spacecraft and leave signals in the CsI detectors installed inside of the telescope.

Insight-HXMT is the first Chinese space X-ray telescope, which was funded jointly by the China National Space Administration (CNSA) and the Chinese Academy of Sciences (CAS). More information about it could be found at: http://www.hxmt.org

GCN Circular 42744

Subject

GRB 251117A: FTW Observations of Swift candidate X-ray sources

Date

2025-11-18T20:56:30Z (2 months ago)

From

Malte Busmann at Ludwig-Maximilians-Universität München <m.busmann@physik.lmu.de>

Via

Web form

Malte Busmann (LMU), Xander J. Hall (CMU), Brendan O'Connor (CMU), Daniel Gruen (LMU), and Antonella Palmese (CMU) report:

We observed the candidate Swift X-ray sources GRB 251117a_X6 and X7 (Evans et al., GCN 42730Loading...
 
 ), as potential counterparts to GRB 251117A (Fermi GBM team, GCN 42719Loading...
 
 ; Airasca et al., GCN 42729Loading...
 
 ; Wang et al., GCN 42731Loading...
 
 ; DeLaunay et al., GCN 42732Loading...
 
 ; Arya et al., GCN 42740Loading...
 
 ) with the Three Channel Imager (3KK) at the Fraunhofer Telescope at Wendelstein Observatory (FTW) in the r, i and J band simultaneously for 10 x 180 s starting at 2025-11-18T17:36:17 UT (1.22 days after the trigger). 

We performed difference imaging with archival images from Legacy Survey and do not detect any new sources down to

r > 23.9 AB mag (3 sigma).

The magnitudes are calibrated against the PS1 catalog and not corrected for Galactic extinction.

We thank Michael Schmidt from the Wendelstein Observatory for obtaining these observations.

GCN Circular 42740

Subject

GRB 251117A: AstroSat CZTI detection

Date

2025-11-18T16:09:35Z (2 months ago)

From

Anuraag Arya at IIT Bombay <aryaanuraag910@gmail.com>

Via

Web form

A. Arya (IITB), A. Goyal (IITB), S. Salunke (IUCAA), M. Tembhurnikar (IUCAA), Harsha K. H. (IUCAA), G. Waratkar (Caltech/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 GRB 251117A which was also detected by Fermi GBM (Fermi GBM Team, GCN Circ. 42719Loading...
 
 ), Fermi LAT (Airasca et. al., GCN Circ. 42729Loading...
 
 ), SVOM/GRM (Wang et. al., GCN Circ. 42731Loading...
 
 ), and Swift BAT-GUANO (DeLaunay et. al., GCN Circ. 42732Loading...
 
 ).

The source was clearly detected in the CsI anticoincidence (Veto) detector in the 100-500 keV energy range. The light curve peaks at 2025-11-17 12:19:52.47 UTC. The measured peak count rate associated with the burst is 424 (+67, -72) counts/s above the background in the combined data of all quadrants, with a total of 561 (+156, -178) counts. The local mean background count rate was 1268 (+11, -12) 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 42737

Subject

GRB 251117A: Fermi GBM observation

Date

2025-11-18T15:50:37Z (2 months ago)

From

Elisabetta Bissaldi at Politecnico and INFN Bari <elisabetta.bissaldi@ba.infn.it>

Via

Web form

E. Bissaldi (Politecnico and INFN Bari) and C. Meegan (UAH)
report on behalf of the Fermi GBM Team:


"At 12:19:52.14 UT on 17 November 2025, the Fermi Gamma-Ray Burst Monitor (GBM)
triggered and located GRB 251117A (trigger 785074797 / 251117514),
which was also detected by the Fermi LAT (Holzmann Airasca et al., GCN 42729Loading...
 
 ), 
SVOM/GRM (Wang et al., GCN 42731Loading...
 
 ) and Swift/BAT-GUANO (DeLaunay et al. 2025, GCN 42732Loading...
 
 ).

The GBM on-ground location (GCN 42719Loading...
 
 ) is consistent with the Fermi LAT position.
The angle from the Fermi LAT boresight at the GBM trigger time is 50 degrees.

The GBM light curve consists of a multi-peaked emission episode
with a duration (T90) of about 1.3 s (50-300 keV).
The time-averaged spectrum from T0-0.32 s to T0+1.15 s is
best fit by a power law function with an exponential
high-energy cutoff. The power law index is -0.80 +/- 0.08 and
the cutoff energy, parameterized as Epeak, is 1.2 +/- 0.3 MeV.

The event fluence (10-1000 keV) in this time interval is
(2.04 +/- 0.08)E-06 erg/cm^2. The 64-ms peak photon flux measured
starting from T0+0.32 s in the 10-1000 keV band
is 11.1 +/- 1.1 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 42732

Subject

GRB 251117A: Swift/BAT-GUANO localization skymap of a short burst

Date

2025-11-18T05:14:33Z (2 months ago)

From

Jimmy DeLaunay at Penn State <delauj2@gmail.com>

Via

Web form

James DeLaunay (PSU), Samuele Ronchini (GSSI), Aaron Tohuvavohu (Cosmic Frontier), Jamie A. Kennea (PSU), Tyler Parsotan (NASA GSFC), Maia Williams (Northwestern) report:

Swift/BAT did not localize GRB 251117A onboard (T0: 2025-11-17T12:19:52.14 UTC, Fermi Trig 785074797, SVOM/GRM GCN 42731

)

The Fermi notice, distributed in near real-time, triggered the Swift Mission Operations Center operated Gamma-ray Urgent Archiver for Novel Opportunities (GUANO; Tohuvavohu et al. 2020, ApJ, 900, 1).

Upon trigger by this notice, GUANO sent a command to the Swift Burst Alert Telescope (BAT) to save 200 seconds of BAT event-mode data from [-50,+150] seconds around the time of the burst. All the requested event mode data was delivered to the ground.

The BAT likelihood search, NITRATES (DeLaunay + Tohuvavohu 2022, ApJ, 941, 169), performed on the temporal window [T0-20 s, T0+20 s], detects the burst with a sqrt(TS) of 10.0 in a 1.024 s analysis time bin, starting at T0 - 0.256 s.

Using the NITRATES analysis, parameter estimation was performed to obtain the localization of this burst in the form of a HEALPIX Multi-Order Coverage (MOC) skymap. This localization accounts for both statistical and systematic errors. More details in the creation and calibration of these maps will soon be published (DeLaunay et al. 2025. in prep)

The 90% credible area is 12,010 deg2 and the 50% credible area is 4,336 deg2. The integrated probability inside the coded field of view is 1%.

The NITRATES skymap is consistent with the Ferm/GBM localization reported in the final position notice (GCN 42719

). The combined Fermi/GBM+NITRATES 90% credible area is 439 deg2 and the 50% credible area is 120 deg2.

The NITRATES and combined localizations are consistent with the Fermi/LAT localization (GCN 42729

)

A plot of the probability skymap can be viewed here:

skymap_plot

The probability skymap and joint skymap files can be downloaded from the links here #The probability skymap file can be downloaded from the link here

skymap_fits_file

joint_skymap_fits_file

Instructions on how to read and manipulate this map can be found here:

https://guano.swift.psu.edu/documentation

More details about this burst can be found on the trigger report page here:

https://guano.swift.psu.edu/trigger_report?id=785074828

GUANO is a fully autonomous, extremely low latency, spacecraft commanding pipeline designed for targeted recovery of BAT event mode data around the times of compelling astrophysical events to enable more sensitive GRB searches.

A live reporting of Swift/BAT event data recovered by GUANO can be found at: https://www.swift.psu.edu/guano/

GCN Circular 42731

Subject

GRB 251117A: SVOM/GRM observation of a short burst

Date

2025-11-18T03:43:19Z (2 months ago)

From

Yue Wang <m18509381757@163.com>

Via

Web form

SVOM/GRM team: Yue Wang, Chen-Wei Wang, Wen-Jun Tan, Shi-Jie Zheng, Yue Huang, Shao-Lin Xiong, Shuang-Nan Zhang (IHEP)

SVOM/ECLAIRs team: 
Olivier GODET (IRAP), Frédéric Piron (LUPM)

Report on behalf of the SVOM team:

SVOM/GRM was triggered in-flight by GRB 251117A (SVOM trigger reference: sb25111701) at 2025-11-17T12:19:52.200 (T0), which is also detected by Fermi/GBM (Fermi GBM Team, GCN #42719Loading...
 
 ) and Fermi/LAT (Airasca et. al., GCN #42729Loading...
 
 ) . 

With the event-by-event data downloaded through the X-band ground station, the GRM light curve shows that this burst consists of multi-peaks with a T90 of 1.2 +1.4/-0.2 s in the 15-5000 keV band.

The SVOM/GRM light curve can be found here:
https://www.bursthub.cn//admin/static/svgrb251117A.png

In addition, the position of this burst, as determined by Fermi/LAT (RA=331.30, Dec = 5.57, GCN #42729Loading...
 
 ), is located at about 39.52 degrees from the SVOM optical axis, which is inside the ECLAIRs field of view. But ECLAIRs was not taking data.

With this localization, the time-averaged spectrum from T0-2 to T0+2 s is best fitted by a power law function with an exponential high-energy cutoff. The power law index is -1.05 +0.10/-0.12 and the cutoff energy, parameterized as Epeak, is 1320 +780/-440 keV. The event fluence (10-1000 keV) in this time interval is (2.10 +0.17/-0.16)E-06 erg/cm^2.  

The localization of GRB 251117A in the 'Amati' relation diagram is shown at: https://www.bursthub.cn//admin/static/svgrb251117A_amati.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: Yue Wang (IHEP) (yuewang@ihep.ac.cn)

GCN Circular 42730

Subject

GRB 251117A: Tiled Swift observations

Date

2025-11-18T01:52:11Z (2 months ago)

From

Phil Evans at U of Leicester <pae9@star.le.ac.uk>

Via


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
Fermi/GBM GRB 251117A. Automated analysis of the XRT data will
be presented online at https://www.swift.ac.uk/xrt_products/TILED_GRB00141

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 Fermi/GBM 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 42729

Subject

GRB 251117A: Fermi-LAT detection

Date

2025-11-18T00:50:18Z (2 months ago)

From

Rahul Gupta at NASA GSFC <rahul.gupta@nasa.gov>

Via

Web form

A. Holzmann Airasca (UniTrento and INFN Bari), S. Lopez (CNRS / IN2P3), N. Di Lalla (Stanford University) and R. Gupta (NASA GSFC) report on behalf of the Fermi-LAT Collaboration:

On November 17, 2025, Fermi-LAT detected high-energy emission from GRB 251117A, which was also detected by Fermi-GBM (trigger 785074797 / 251117514, GCN 42719Loading...
 
 ). The best LAT on-ground location is found to be:

RA, Dec = 331.30, 5.57 (J2000)

with an error radius of 0.72 deg (90 % containment, statistical error only). This was 51 deg from the LAT boresight at the time of the GBM trigger (T0 = 12:19:52.14 UT).

The data from the Fermi-LAT shows a significant increase in the event rate that is spatially and temporally correlated with the GBM emission with high significance. The photon flux above 100 MeV in the time interval 0 - 5 s after the GBM trigger is (3.4 ± 1.4) E-4 ph/cm2/s. The estimated photon index above 100 MeV is -2.8 ± 0.6. The highest-energy photon is a 0.9 GeV event which is observed ~ 2 seconds after the GBM trigger.

A Swift ToO has been requested for this burst.

The Fermi-LAT point of contact for this burst is Aldana Holzmann Airasca (a.holzmannairasca@unitn.it).

The Fermi-LAT is a pair conversion telescope designed to cover the energy band from 20 MeV to greater than 300 GeV. It is the product of an international collaboration between NASA and DOE in the U.S. and many scientific institutions across France, Italy, Japan and Sweden.

GCN Circular 42719

Subject

GRB 251117A: Fermi GBM Final Localization Correction

Date

2025-11-17T13:55:50Z (2 months ago)

From

Elisabetta Bissaldi at Politecnico and INFN Bari <elisabetta.bissaldi@ba.infn.it>

Via

Web form

The Fermi GBM team reports the detection of a likely SHORT GRB.

At 12:19:52.14 UT on 17 November 2025, the Fermi Gamma-ray Burst Monitor (GBM)
triggered and located GRB 251117A (trigger 785074797/251117514).
This trigger was initially classified as Below horizon by the flight software,
but is in fact due to a GRB.

The on-ground calculated location, using the Fermi GBM trigger data,
is RA = 335.05, Dec = 5.01 (J2000 degrees, equivalent to J2000  22h 20m, +05d 00'),
with a statistical uncertainty of 4.40 degrees.

The angle from the Fermi LAT boresight is 52 degrees.

The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn251117514/quicklook/glg_skymap_all_bn251117514.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/bn251117514/quicklook/glg_healpix_all_bn251117514.fit

The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn251117514/quicklook/glg_lc_medres34_bn251117514.gif