GRB 251115A
GCN Circular 42733
Subject
GRB 251115A: Swift-XRT observations
Date
2025-11-18T10:09:35Z (3 days ago)
From
Phil Evans at U of Leicester <pae9@star.le.ac.uk>
Via
email
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 42697
Subject
GRB 251115A: Tiled Swift observations
Date
2025-11-15T13:11:54Z (6 days ago)
From
Phil Evans at U of Leicester <pae9@star.le.ac.uk>
Via
email
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 42696
Subject
GRB 251115A: Fermi-LAT detection
Date
2025-11-15T12:51:17Z (6 days ago)
From
A. Holzmann Airasca at University of Trento and INFN Bari <a.holzmannairasca@unitn.it>
Via
Web form
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 42694
Subject
Fermi GRB 251115A: Global MASTER-Net observations report
Date
2025-11-15T04:30:41Z (6 days ago)
From
Vladimir Lipunov at Moscow State U/Krylov Obs <lipunov@xray.sai.msu.ru>
Via
email
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 Circular 42692
Subject
GRB 251115A: Fermi GBM Final Real-time Localization
Date
2025-11-15T03:30:39Z (6 days 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 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