Gamma-ray Burst 251115A

(All information courtesy of the instrument teams.)

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Results of Observations

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Sat 15 Nov 25 03:20:32 UT
NOTICE_TYPE:     Fermi-GBM Flight Position
RECORD_NUM:      46
TRIGGER_NUM:     784869607
GRB_RA:          330.817d {+22h 03m 16s} (J2000),
                 331.158d {+22h 04m 38s} (current),
                 330.157d {+22h 00m 38s} (1950)
GRB_DEC:          -8.033d {-08d 01' 59"} (J2000),
                  -7.907d {-07d 54' 25"} (current),
                  -8.276d {-08d 16' 31"} (1950)
GRB_ERROR:       5.60 [deg radius, statistical plus systematic]
GRB_INTEN:       382 [cnts/sec]
DATA_SIGNIF:     19.90 [sigma]
INTEG_TIME:      1.024 [sec]
GRB_DATE:        20994 TJD;   319 DOY;   25/11/15
GRB_TIME:        12002.67 SOD {03:20:02.67} UT
GRB_PHI:         240.00 [deg]
GRB_THETA:        75.00 [deg]
DATA_TIME_SCALE: 1.0240 [sec]
HARD_RATIO:      1.32
LOC_ALGORITHM:   3 (version number of)
MOST_LIKELY:      97%  GRB
2nd_MOST_LIKELY:   1%  Generic SGR
DETECTORS:       0,0,0, 0,0,0, 0,1,1, 0,0,0, 0,0,
SUN_POSTN:       230.61d {+15h 22m 27s}  -18.52d {-18d 31' 18"}
SUN_DIST:         97.36 [deg]   Sun_angle= -6.7 [hr] (East of Sun)
MOON_POSTN:      176.71d {+11h 46m 51s}   +0.43d {+00d 25' 56"}
MOON_DIST:       153.46 [deg]
MOON_ILLUM:      22 [%]
GAL_COORDS:       50.58,-45.90 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      330.03,  3.66 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL:          http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn251115139/quicklook/glg_lc_medres34_bn251115139.gif
COMMENTS:        Fermi-GBM Flight-calculated Coordinates.  
COMMENTS:        This trigger occurred at longitude,latitude = 119.33,-11.27 [deg].  
COMMENTS:        The LC_URL file will not be created until ~15 min after the trigger.

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Sat 15 Nov 25 03:20:49 UT
NOTICE_TYPE:     Fermi-GBM Ground Position
RECORD_NUM:      58
TRIGGER_NUM:     784869607
GRB_RA:          332.980d {+22h 11m 55s} (J2000),
                 333.321d {+22h 13m 17s} (current),
                 332.321d {+22h 09m 17s} (1950)
GRB_DEC:          -8.290d {-08d 17' 23"} (J2000),
                  -8.161d {-08d 09' 40"} (current),
                  -8.537d {-08d 32' 13"} (1950)
GRB_ERROR:       2.79 [deg radius, statistical only]
DATA_SIGNIF:     24.30 [sigma]
DATA_INTERVAL:   2.048 [sec]
GRB_DATE:        20994 TJD;   319 DOY;   25/11/15
GRB_TIME:        12002.67 SOD {03:20:02.67} UT
GRB_PHI:         238.00 [deg]
GRB_THETA:        76.00 [deg]
E_RANGE:         44.032 - 279.965 [keV]
LOC_ALGORITHM:   4173 (Gnd S/W Version number)
SUN_POSTN:       230.61d {+15h 22m 27s}  -18.52d {-18d 31' 18"}
SUN_DIST:         99.29 [deg]   Sun_angle= -6.8 [hr] (East of Sun)
MOON_POSTN:      176.71d {+11h 46m 51s}   +0.43d {+00d 25' 52"}
MOON_DIST:       155.44 [deg]
MOON_ILLUM:      22 [%]
GAL_COORDS:       51.89,-47.87 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      331.94,  2.67 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL:          http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn251115139/quicklook/glg_lc_medres34_bn251115139.gif
POS_MAP_URL:     http://gcn.gsfc.nasa.gov/notices_f/gbm_gnd_loc_map_784869607.fits
COMMENTS:        Fermi-GBM Ground-calculated Coordinates.  
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:     Sat 15 Nov 25 03:29:27 UT
NOTICE_TYPE:     Fermi-GBM Final Position
RECORD_NUM:      0
TRIGGER_NUM:     784869607
GRB_RA:          334.510d {+22h 18m 02s} (J2000),
                 334.846d {+22h 19m 23s} (current),
                 333.860d {+22h 15m 26s} (1950)
GRB_DEC:          -4.460d {-04d 27' 35"} (J2000),
                  -4.330d {-04d 19' 46"} (current),
                  -4.711d {-04d 42' 37"} (1950)
GRB_ERROR:       4.12 [deg radius, statistical only]
GRB_DATE:        20994 TJD;   319 DOY;   25/11/15
GRB_TIME:        12002.67 SOD {03:20:02.67} UT
GRB_PHI:         239.00 [deg]
GRB_THETA:        80.00 [deg]
E_RANGE:         44.032 - 279.965 [keV]
LOC_ALGORITHM:   41731 (Gnd S/W Version number)
SUN_POSTN:       230.62d {+15h 22m 28s}  -18.52d {-18d 31' 23"}
SUN_DIST:        102.03 [deg]   Sun_angle= -6.9 [hr] (East of Sun)
MOON_POSTN:      176.78d {+11h 47m 07s}   +0.40d {+00d 23' 46"}
MOON_DIST:       157.74 [deg]
MOON_ILLUM:      22 [%]
GAL_COORDS:       57.85,-47.00 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      334.74,  5.70 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL:          http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn251115139/quicklook/glg_lc_medres34_bn251115139.gif
LOC_URL:         http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn251115139/quicklook/glg_locplot_all_bn251115139.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 Long GRB.

GCN Circular #42692
The Fermi GBM team reports the detection of a likely LONG GRB
At 03:20:02 UT on 15 Nov 2025, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 251115A (trigger 784869607.66655 / 251115139).
The on-ground calculated location, using the Fermi GBM trigger data, is RA = 334.5, Dec = -4.5 (J2000 degrees, equivalent to J2000 22h 18m, -4d 30'), with a statistical uncertainty of 4.1 degrees.
The angle from the Fermi LAT boresight is 80.0 degrees.
The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn251115139/quicklook/glg_skymap_all_bn251115139.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/bn251115139/quicklook/glg_healpix_all_bn251115139.fit
The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn251115139/quicklook/glg_lc_medres34_bn251115139.gif

GCN Circular #42694
V.Lipunov, E.Gorbovskoy, A.Kuznetsov, K.Zhirkov, I.Panchenko, N.Tiurina, P.Balanutsa, V.Topolev, D.Vlasenko, G.Antipov, A.Sankovich, Yu.Tselik, 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.Sosnovskij (CrAO), 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-OAFA robotic telescope [1] located in Argentina (OAFA observatory of San Juan National University) started inspect of the Fermi GRB 251115A ( Fermi GBM team, GCN 42692) errorbox 41 sec after notice time and 74 sec after trigger time at 2025-11-15 03:21:17 UT, with upper limit up to 20.0 mag. The observations began at zenith distance = 64 deg. The sun altitude is -38.6 deg.
The galactic latitude b = -47 deg., longitude l = 59 deg.
Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=3042754
We obtain a following upper limits.

Tmid-T0  |      Date Time      |          Site       |             Coord (J2000)          |Filt.| Expt. | Limit| Comment
_________|_____________________|_____________________|____________________________________|_____|_______|_______|________

      80 | 2025-11-15 03:21:17 |         MASTER-OAFA | (22h 03m 35.41s , -07d 54m 09.9s) |   C |    10 | 18.6 |        
     101 | 2025-11-15 03:21:33 |         MASTER-OAFA | (22h 03m 35.36s , -07d 54m 09.6s) |   C |    20 | 19.0 |        
     141 | 2025-11-15 03:22:09 |         MASTER-OAFA | (22h 12m 15.81s , -08d 11m 40.7s) |   C |    30 | 19.4 |        
     178 | 2025-11-15 03:22:45 |         MASTER-OAFA | (22h 12m 15.80s , -08d 11m 40.4s) |   C |    30 | 19.4 |        
     219 | 2025-11-15 03:23:21 |         MASTER-OAFA | (22h 12m 15.79s , -08d 11m 40.4s) |   C |    40 | 19.5 |        
     270 | 2025-11-15 03:24:07 |         MASTER-OAFA | (22h 12m 15.78s , -08d 11m 40.0s) |   C |    50 | 19.7 |        
     331 | 2025-11-15 03:25:03 |         MASTER-OAFA | (22h 12m 15.78s , -08d 11m 40.0s) |   C |    60 | 19.8 |        
     658 | 2025-11-15 03:30:00 |         MASTER-OAFA | (22h 18m 22.95s , -04d 21m 04.4s) |   C |   120 | 20.0 |        
     794 | 2025-11-15 03:32:06 |         MASTER-OAFA | (22h 18m 22.96s , -04d 21m 04.5s) |   C |   140 | 20.0 |        
     955 | 2025-11-15 03:34:32 |         MASTER-OAFA | (22h 18m 22.96s , -04d 21m 04.4s) |   C |   170 | 20.0 |        
    1076 | 2025-11-15 03:37:28 |         MASTER-OAFA | (22h 18m 22.99s , -04d 21m 04.2s) |   C |    60 | 19.5 |        
    1141 | 2025-11-15 03:38:34 |         MASTER-OAFA | (22h 18m 23.03s , -04d 21m 04.4s) |   C |    60 | 19.5 |        
    1207 | 2025-11-15 03:39:39 |         MASTER-OAFA | (22h 18m 23.03s , -04d 21m 04.4s) |   C |    60 | 19.4 |

Filter C is a clear (unfiltred) band.
The observation and reduction will continue. The message may be cited.
[1] - V.M. Lipunov, V.G. Kornilov, E.S. Gorbovskoy, N.A. Tiurina & A.S.Kuznetsov, 2023, Astronomical Robotic Networks and Operative Multichanel Astrophysics, Lomonosov MSU PRESS, 591pp. http : // www.pereplet.ru/lipunov/625.html

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Sat 15 Nov 25 10:40:52 UT
NOTICE_TYPE:     Fermi-LAT Offline Position
TRIGGER_NUM:     784869607
GRB_RA:          330.175d {+22h 00m 42s} (J2000),
                 330.518d {+22h 02m 04s} (current),
                 329.512d {+21h 58m 03s} (1950)
GRB_DEC:          -9.181d {-09d 10' 50"} (J2000),
                  -9.056d {-09d 03' 20"} (current),
                  -9.422d {-09d 25' 17"} (1950)
GRB_ERROR:       22.80 [arcmin radius, 90% containment, statistical only]
GRB_DATE:        20994 TJD;   319 DOY;   25/11/15
GRB_TIME:        12002.67 SOD {03:20:02.67} UT
TRIGGER_ID:      0x0
MISC:            0x40000000
SUN_POSTN:       230.93d {+15h 23m 42s}  -18.60d {-18d 35' 57"}
SUN_DIST:         96.07 [deg]   Sun_angle= -6.6 [hr] (East of Sun)
MOON_POSTN:      179.99d {+11h 59m 57s}   -1.35d {-01d 20' 50"}
MOON_DIST:       148.85 [deg]
MOON_ILLUM:      20 [%]
GAL_COORDS:       48.69,-45.94 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      329.03,  2.80 [deg] ecliptic lon,lat of the burst (or transient)
COMMENTS:        Fermi LAT Offline position.  
COMMENTS:        This Notice was ground-generated -- not flight-generated.  
COMMENTS:        It is the result of human-in-the-loop processing.  
COMMENTS:        This is a human generated position of a LAT ground detection.  
COMMENTS:        This source corresponds to GBM trigger.

GCN Circular #42696
E. Bissaldi (Politecnico and INFN Bari), A. Holzmann Airasca (UniTrento and INFN Bari), R. Gupta (NASA GSFC), T. Nymark (KTH), F. Longo (University and INFN, Trieste) and S. Lopez (CNRS / IN2P3) report on behalf of the Fermi-LAT Collaboration:
On November 15, 2025, Fermi-LAT detected high-energy emission from GRB 251115A, which was also detected by Fermi-GBM (trigger 784869607 / 251115139, GCN 42692) and Global MASTER (GCN 42694).
The best LAT on-ground location is found to be:
RA, Dec = 330.18, -9.18 (J2000)
with an error radius of 0.36 deg (90 % containment, statistical error only). This was 80 deg from the LAT boresight at the time of the GBM trigger (T0 = 03:20:02.67 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 - 600 s after the GBM trigger is (1.04 ± 0.34) E-5 ph/cm2/s. The estimated photon index above 100 MeV is -2.5 ± 0.4. The highest-energy photon is a 1.6 GeV event which is observed ~ 490 seconds after the GBM trigger.
A Swift ToO has been approved for this burst.
The Fermi-LAT point of contact for this burst is Tanja Kramer Nymark (tanjan@kth.se).
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 #42697
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/LAT GRB 251115A. Automated analysis of the XRT data will be presented online at https://www.swift.ac.uk/xrt_products/TILED_GRB00140
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/LAT 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 #42733
S. Dichiara (PSU), J.A. Kennea (PSU), K.L. Page (U. Leicester), A.P. Beardmore (U. Leicester), T. Sbarrato (INAF-OAB), P. D'Avanzo (INAF-OAB), M.G. Bernardini (INAF-OAB), D.N. Burrows (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/LAT-detected burst GRB 251115A in a series of observations tiled on the sky. The total exposure time is 4.9 ks, distributed over 5 tiles; the maximum exposure at a single sky location in the tiling was 2.1 ks. The data were collected between T0+35.6 ks and T0+80.1 ks, and are entirely in Photon Counting (PC) mode.
Six 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):  330.1753  =  22h 00m 42.06s
  Dec (J2000.0): -9.3644  =  -09d 21' 51.7"
  Error: 8.5 arcsec (radius, 90% conf.)
  Count-rate: (3.7 [+2.2, -1.6])e-3 ct s^-1   
  Distance: 660 arcsec from Fermi/LAT position.

Source 2:

  RA (J2000.0):  330.0683  =  22h 00m 16.38s
  Dec (J2000.0): -9.4681  =  -09d 28' 05.0"
  Error: 8.6 arcsec (radius, 90% conf.)
  Count-rate: (6.2 [+3.9, -2.8])e-3 ct s^-1   
  Distance: 1100 arcsec from Fermi/LAT position.

Source 3:

  RA (J2000.0):  330.0530  =  22h 00m 12.72s
  Dec (J2000.0): -9.1976  =  -09d 11' 51.3"
  Error: 5.8 arcsec (radius, 90% conf.)
  Count-rate: (4.3 [+2.3, -1.7])e-3 ct s^-1   
  Distance: 437 arcsec from Fermi/LAT position.
  Flux: (2.26 [+1.23, -0.91])e-13 erg cm^-2 s^-1 (observed, 0.3-10 keV)

Source 4:

  RA (J2000.0):  330.2127  =  22h 00m 51.06s
  Dec (J2000.0): -9.1608  =  -09d 09' 38.9"
  Error: 14.1 arcsec (radius, 90% conf.)
  Count-rate: (9.6 [+4.4, -3.4])e-3 ct s^-1   
  Distance: 152 arcsec from Fermi/LAT position.
  Flux: (3.6 [+1.6, -1.2])e-13 erg cm^-2 s^-1 (observed, 0.3-10 keV)

Source 6:

  RA (J2000.0):  329.7737  =  21h 59m 05.69s
  Dec (J2000.0): -8.8965  =  -08d 53' 47.2"
  Error: 5.6 arcsec (radius, 90% conf.)
  Count-rate: 0.0113 [+0.0055, -0.0042] ct s^-1   
  Distance: 1756 arcsec from Fermi/LAT position.
  Flux: (4.5 [+2.2, -1.7])e-13 erg cm^-2 s^-1 (observed, 0.3-10 keV)

Source 7:

  RA (J2000.0):  329.8892  =  21h 59m 33.40s
  Dec (J2000.0): -8.9944  =  -08d 59' 39.8"
  Error: 6.6 arcsec (radius, 90% conf.)
  Count-rate: 0.0101 [+0.0049, -0.0038] ct s^-1   
  Distance: 1218 arcsec from Fermi/LAT position.
  Flux: (2.63 [+1.28, -0.99])e-13 erg cm^-2 s^-1 (observed, 0.3-10 keV)

A catalogued source was also detected.
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_GRB00140.
This circular is an official product of the Swift-XRT team.

GCN Circular #42792
A. Jameson (UAH), S. Bala (USRA), and C. Meegan (UAH) report on behalf of the Fermi Gamma-ray Burst Monitor Team:
"At 03:20:02.67 UT on 15 November 2025, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 251115A (trigger 784869607/251115139), which was also detected by Fermi-LAT (E. Bissaldi et al. 2025, GCN 42696). The Fermi GBM on-ground location is consistent with the Fermi-LAT position.
The angle from the Fermi LAT boresight is 80 degrees.
The GBM light curve consists of a double-peaked emission with a duration (T90) of about 13 s (50-300 keV). The time-averaged spectrum from T0-4.1 to T0+13.8 s is best fit by a Band function with Epeak = 36 +/- 6 keV, alpha = -0.7 +/- 0.4, and beta = -2.09 +/- 0.07.
The event fluence (10-1000 keV) in this time interval is (3.5 +/- 0.2)E-06 erg/cm^2. The 1-sec peak photon flux measured starting from T0+0.064 s in the 10-1000 keV band is 9.0 +/- 0.3 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/"

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Jochen Greiner, last update: 22-Nov-2025 [Disclaimer]