GRB 260709A

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

SVOM/ECLAIRs team: Sebastien Guillot (IRAP)

Report on behalf of the SVOM team:

SVOM/GRM detected GRB 260709A during the routine ground search at 2026-07-09T01:07:50.900 (T0), which is also detected by Fermi/GBM (Fermi GBM Team, GCN #45121
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 ).

With the event-by-event data downloaded through the X-band ground station, the GRM light curve shows that this burst mainly consists of multiple pulses with a T90 of 63 +9/-9 s in the 15-5000 keV band.

The SVOM/GRM light curve can be found here:
https://www.bursthub.cn/gcn/2026/svgrb260709A.png

In addition, the position of this burst, according to Fermi/GBM localization (RA = 84.1, Dec = 74.0, Fermi GBM Team, GCN #45121
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 ), is located at about 119 degrees from the SVOM optical axis, which is outside the ECLAIRs field of view.

With this localization, the time-averaged spectrum from T0-25 to T0+25 s is fitted by a power law function. The power law index is -2.87 +0.16/-0.09. The event fluence (10-1000 keV) in this time interval is (3.0 +1.0/-1.2)E-05 erg/cm^2.

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: Jin-Peng Zhang (IHEP) (zhangjinpeng@ihep.ac.cn)

Jin-Peng Zhang, Chen-Wei Wang, Shao-Lin Xiong (IHEP) report on behalf of GECAM team:

GECAM-B was triggered in-flight by GRB 260709A, at 2026-07-09T01:07:32.000 UTC (denoted as T0), which is also detected by Fermi/GBM (Fermi GBM team, GCN #45121
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 ).

According to the GECAM-B light curves in about 70-6000 keV, this burst mainly consists of several pulses, with a duration (T90) of 56 +5/-4 s.

The GECAM-B light curve can be found here:
https://www.bursthub.cn/gcn/2026/gecambgrb260709A.png

The time-averaged spectrum from T0 - 5 to T0 + 50 s (photon energy > 70 keV) is fitted by a power law function. The power law index is -2.38 +0.25/-0.25. The event fluence (10-1000 keV) in this time interval is (1.5 +0.5/-0.3)E-05 erg/cm^2.

Gravitational wave high-energy Electromagnetic Counterpart All-sky Monitor (GECAM) mission originally consists of two micro-satellites (GECAM-A and GECAM-B) launched in Dec. 2020. As the third member of GECAM constellation, GECAM-C was launched onboard SATech-01 experimental satellite in July 2022. GECAM mission is funded by the Chinese Academy of Sciences (CAS).

The Fermi GBM team reports the detection of a likely LONG GRB

At 01:07:32 UT on 9 Jul 2026, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 260709A (trigger 805252057.543312 / 260709047).

The on-ground calculated location, using the Fermi GBM trigger data, is RA = 84.1, Dec = 74.0 (J2000 degrees, equivalent to J2000 05h 36m, 74d 00'), with a statistical uncertainty of 4.0 degrees.

The angle from the Fermi LAT boresight is 106.0 degrees.

The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260709047/quicklook/glg_skymap_all_bn260709047.png

The HEALPix FITS file, including the estimated localization systematic, can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260709047/quicklook/glg_healpix_all_bn260709047.fit

The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260709047/quicklook/glg_lc_medres34_bn260709047.gif