2026-05-16T01:47:43.156Z | rev 2
Longhao Li, Tingkai Sun, Chenyv Wang report on behalf of the GRID Collaboration:
GRID-09 reports the detection of the long-duration GRB 260507A, which was also detected by Fermi GBM (GCN Circular 44493), MASS-Cube (GRID 2.0,GCN Circular 44583).
The event was triggered with GRID on 2026-05-07 at 20:28:00 UTC. The measured burst duration (T90) in the 30-2000 keV range is approximately 12.1 +/- 2.8 seconds.
The GRID light curve of this event can be found at https://mirrors.tuna.tsinghua.edu.cn/GRID/data/GRID-GCN/GRB260507A/GRID_260507A_ltcv.pdf.
GRID is a student-led project to monitor the transient gamma-ray sky with multiple detectors onboard different nanosatellites in the era of multi-messenger astronomy. For more information about GRID, please refer to the following references: https://doi.org/10.1007/s10686-019-09636-w and https://doi.org/10.1007/s10686-021-09819-4.
2026-05-16T01:47:43.156Z | rev 2
Longhao Li, Tingkai Sun, Chenyv Wang report on behalf of the GRID Collaboration:
GRID-09 reports the detection of the long-duration GRB 260507A, which was also detected by Fermi GBM (GCN Circular 44493), MASS-Cube (GRID 2.0,GCN Circular 44583).
The event was triggered with GRID on 2026-05-07 at 20:28:00 UTC. The measured burst duration (T90) in the 30-2000 keV range is approximately 12.1 +/- 2.8 seconds.
The GRID light curve of this event can be found at https://mirrors.tuna.tsinghua.edu.cn/GRID/data/GRID-GCN/GRB260507A/GRID_260507A_ltcv.pdf.
GRID is a student-led project to monitor the transient gamma-ray sky with multiple detectors onboard different nanosatellites in the era of multi-messenger astronomy. For more information about GRID, please refer to the following references: https://doi.org/10.1007/s10686-019-09636-w and https://doi.org/10.1007/s10686-021-09819-4.
GCN 44583: MASS-Cube (GRID 2.0) detection of GRB 260507A
2026-05-12T16:33:06.819Z | rev 0
Jiahuan Zhu, Chenyu Wang, Xutao Zheng, Hao Chang, Zirui Yang report on behalf of the MASS-Cube Collaboration:
MASS-Cube reports the detection of the long-duration GRB 260507A, which was also detected by Fermi/GBM (GCN Circular 44493) and GRID-09.
The event was triggered by MASS-Cube on 2026-05-07 at 20:27:59.7 UTC. The measured burst duration (T90) in the 50-10000 keV range is approximately 19.3 +/- 3.2 seconds.
The MASS-Cube light curve of this event can be found at https://mirrors.tuna.tsinghua.edu.cn/GRID/data/GRID-GCN/GRB260507A/MASS_Cube_260507A_ltcv.pdf.
MASS-Cube is a pathfinder for a 3D position-sensitive Compton telescope in space, currently considered the next generation of the GRID constellation in the era of multi-messenger astronomy. For more information about MASS-Cube, please refer to the following reference: https://doi.org/10.1007/s10686-024-09920-4.
GCN 44497: EP260507a: SVOM/VT optical observations
2026-05-08T03:08:14.057Z | rev 0
H. L. Li, L. P. Xin, C. Wu, Y. L. Qiu, Y. N. Ma, Z. H. Yao, J. R. Xu, X. H. Han, J. Wang, Y. Xu, P. P. Zhang, W. J. Xie, Y. J. Xiao, H. B. Cai, L. Lan, J. S. Deng, J. Y. Wei (NAOC), J. Palmerio (CEA/Irfu) report on behalf of the SVOM/VT team.
SVOM/VT performed observations with automatic follow-up observations to the Xray transient EP260507a triggered by Einstein Probe (Fu et al., GCN 44488). The observation started at 2026-05-07T14:45:27 UTC, i.e. 57.5 minutes post trigger and lasted for 2 orbits (about 1.9 hours) in the VT_B (400-650 nm) and VT_R (650-1000 nm) channels simultaneously.
The optical counterpart (Corcoran et al., GCN 44489; Sankar et al., GCN 44490; Jiang et al., GCN 44491; Kumar et al., GCN 44492; Eyles-Ferris et al., GCN 44495; Jiang et al., GCN 44496) was clearly detected in both channels. The measurements in AB magnitude are as follows:
Mid time | Band | Exposure Time | Brightness
1.35 h VT_B 56*50 s 21.92 +/- 0.12 mag
1.35 h VT_R 55*50 s 20.91 +/- 0.08 mag
2.96 h VT_B 56*50 s 22.29 +/- 0.14 mag
2.96 h VT_R 55*50 s 21.25 +/- 0.10 mag
Our photometry was not corrected for Galactic extinction.
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. VT was jointly developed by Xi'an Institute of Optics and Precision Mechanics (XIOPM), CAS and National astronomical observatories (NAOC), CAS.
GCN 44493: GRB 260507A: Fermi GBM Final Real-time Localization
2026-05-07T20:38:34.367Z | rev 0
The Fermi GBM team reports the detection of a likely LONG GRB
At 20:28:00 UT on 7 May 2026, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 260507A (trigger 799878485.453562 / 260507853).
The on-ground calculated location, using the Fermi GBM trigger data, is RA = 287.5, Dec = -21.3 (J2000 degrees, equivalent to J2000 19h 10m, -21d 18'), with a statistical uncertainty of 2.4 degrees.
The angle from the Fermi LAT boresight is 79.0 degrees.
The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260507853/quicklook/glg_skymap_all_bn260507853.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/bn260507853/quicklook/glg_healpix_all_bn260507853.fit
The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260507853/quicklook/glg_lc_medres34_bn260507853.gif