GCN 45080: Fermi GBM Sub-Threshold Detection of GRB 260705A
2026-07-05T20:33:37.494Z | rev 3
R. Hamburg (USRA) and P. Veres (UAH) report on behalf of the Fermi-GBM Team:
SVOM ECLAIRs detected GRB 260702A on 2026-07-05 at 13:06:46 UTC (Saccardi et al 2026; GCN 45079). There was no Fermi-GBM onboard trigger around this event time. An automated, blind search for gamma-ray bursts below the onboard triggering threshold in Fermi-GBM identified no candidates.
The GBM Targeted Search [1], the most sensitive coherent search for GRB-like signals in GBM, identified a transient starting about 8 seconds after the SVOM ECLAIRs best SNR time of 2026-07-05 13:06:28 UTC. The Fermi-MET for this transient is 804949601.573 s. The transient is found most significantly on the 32 s timescale with a false alarm rate of 1.4e-04 Hz. The Targeted Search localization is found to be spatially consistent with the SVOM ECLAIRs localization.
The GBM Targeted Search event was found with the highest significance using a "normal" spectrum (Band function with Epeak = 230 keV, alpha = -1.0, beta = -2.3) for a GRB.
[1] Goldstein et al. 2019 arXiv:1903.12597
GCN 41149: Fermi GRB 250725A: Global MASTER-Net observations report
2025-07-25T02:00:36.557Z | rev 2
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 (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in Argentina (OAFA observatory of San Juan National University) started inspect of the Fermi GRB250725.08 (trigger No 775101099,02h 08m 43.20s , -85d 24m 00.0s, R=1.74) errorbox 13 sec after notice time and 47 sec after trigger time at 2025-07-25 01:52:22 UT, with upper limit up to 19.0 mag. The observations began at zenith distance = 64 deg. The sun altitude is -50.5 deg.
MASTER-SAAO robotic telescope located in South Africa (South African Astronomical Observatory) started inspect of the Fermi GRB250725.08 errorbox 20 sec after notice time and 54 sec after trigger time at 2025-07-25 01:52:29 UT, with upper limit up to 17.0 mag. The observations began at zenith distance = 53 deg. The sun altitude is -46.5 deg.
The galactic latitude b = -32 deg., longitude l = 301 deg.
Real time updated cover map and OT discovered available here:
https://master.sai.msu.ru/site/master2/observ.php?id=2947370
We obtain a following upper limits.
Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment
_________|_____________________|_____________________|____________________________________|_____|_______|_______|________
52 | 2025-07-25 01:52:22 | MASTER-OAFA | (02h 25m 24.07s , -83d 05m 36.9s) | C | 10 | 18.2 |
60 | 2025-07-25 01:52:29 | MASTER-SAAO | (02h 09m 37.42s , -82d 51m 47.1s) | P/ | 10 | 16.1 |
60 | 2025-07-25 01:52:29 | MASTER-SAAO | (02h 24m 15.37s , -83d 06m 32.9s) | P\\ | 10 | 16.5 |
68 | 2025-07-25 01:52:38 | MASTER-OAFA | (02h 25m 23.82s , -83d 05m 36.2s) | C | 10 | 18.3 |
89 | 2025-07-25 01:52:54 | MASTER-OAFA | (02h 25m 23.31s , -83d 05m 34.7s) | C | 20 | 18.7 |
94 | 2025-07-25 01:52:58 | MASTER-SAAO | (02h 09m 37.12s , -82d 51m 49.2s) | P/ | 20 | 16.8 |
94 | 2025-07-25 01:52:58 | MASTER-SAAO | (02h 24m 15.31s , -83d 06m 34.5s) | P\\ | 20 | 17.0 |
116 | 2025-07-25 01:53:20 | MASTER-OAFA | (02h 25m 22.79s , -83d 05m 34.2s) | C | 20 | 18.7 |
133 | 2025-07-25 01:53:37 | MASTER-SAAO | (02h 24m 14.91s , -83d 06m 36.1s) | P\\ | 20 | 17.0 |
147 | 2025-07-25 01:53:46 | MASTER-OAFA | (02h 25m 21.97s , -83d 05m 32.7s) | C | 30 | 19.0 |
183 | 2025-07-25 01:54:22 | MASTER-OAFA | (02h 25m 21.21s , -83d 05m 31.3s) | C | 30 | 19.0 |
Filter C is a clear (unfiltred) band.
The observation and reduction will continue.
The message may be cited.