GCN Circular 45940
GRID detection of GRB 261010A
From: GRID Student Team at Tsinghua University
Issued: 2026-10-13 12:32 UTC
Type: GRB, Gamma-ray Transient
# GRID detection of GRB 261010A
Zihan Yu, Chenyu Wang, Xinyu Liu report on behalf of the GRID Collaboration:
GRID-11B reports the detection of the long-duration GRB 261010A, which was also detected by Fermi GBM (GCN Circular 45888, 45911), Swift BAT (GCN Circular 45889, 45918), and Konus-Wind (GCN Circular 45925).
X-ray and optical afterglow detections were reported by Swift XRT (GCN Circular 45889, 45894, 45935), NOT/ALFOSC (GCN Circular 45890, 45912), and the OSN 1.5m telescope (GCN Circular 45891).
We adopt 2026-10-10 at 19:17:03 UTC, the Fermi GBM trigger time, as T0. Using a source interval from T0-2 to T0+8 s, the measured burst duration (T90) using events selected in the 30-2000 keV range of the GRID-11B FITS energy column is approximately 5.4 +/- 1.2 seconds (statistical uncertainty).
The extended emission reported by other instruments is not clearly seen in the GRID-11B light curve. The reported T90 characterizes the main emission episode.
The GRID light curve of this event can be found at https://mirrors.tuna.tsinghua.edu.cn/GRID/data/GRID-GCN/GRB261010A/GRID_261010A_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: Client Challenge (doi.org) and Client Challenge (doi.org) .
Every one of the gamma-ray bursts GCN reports is posted here.
Relayed automatically from NASA's General Coordinates Network.
Transient Alerts » in reply to GRB 261010A
In plain words Notable
On 10 October 2026 several gamma-ray satellites (Fermi, Swift, Konus-Wind and others) recorded a burst of gamma rays in the constellation Hercules that lasted about a minute. Swift's X-ray telescope and ground telescopes quickly found a fading X-ray and optical afterglow, which confirms the position. The host galaxy is uncertain: it is either a nearby galaxy about 25 arcseconds away at redshift 0.070, or a fainter galaxy 2 arcseconds away at redshift 0.785, meaning the light left roughly 7 billion years ago. Several teams say the burst's flash pattern and energy look more like those of a merger of two compact stars (such as neutron stars) than the collapse of a massive star, even though the burst was long. No kilonova (the glow from freshly made heavy elements after a merger) has been seen, and radio searches found nothing; the deep, late near-infrared images are too shallow to rule one out.
How unusual is it? A long gamma-ray burst with an optical afterglow, a measured redshift, and several independent analyses pointing to a merger origin is out of the ordinary, but no kilonova has been seen and the host is unconfirmed. It would become exceptional if a kilonova were confirmed, and would drop back toward routine if the burst were shown to come from a collapsing massive star.
Written by an AI model (claude-sonnet-5-5) from the official reports in this thread, and rewritten as new reports arrived (version 9); last updated . It may contain mistakes: the reports themselves are the authority.
GRID detection of GRB 261010A
The whole thread (25 posts)
- GRB 261010A
- GRB261010A: Retraction of Keck/MOSFIRE near-IR source
- GRB 261010A: Pan-STARRS z-band imaging and upper limit
- GRB 261010A: VLA radio observations
- GRB261010A: Keck/MOSFIRE detection of a near-IR source
- GRB 261010A: ASKAP non-detection of a radio afterglow
- GRB 261010A: LBT tentative near-infrared detection
- GRB 261010A: Glowbug gamma-ray detection
- GRB 261010A: initial pulse rest-frame energetics from Konus-Wind detection
- GRB 261010A: a short minimum variability timescale and a distinct pulse evolution compatible with a merger origin
- GRID detection of GRB 261010A
- GRB 261010A: J-band upper limit by the SYSU 80cm infrared telescope
- GRB 261010A: Swift-XRT refined Analysis
- GRB 261010A: a Type I-L (merger-driven) GRB candidate
- Updated explainer: what the latest reports add (AI-written)
- GRB 261010A: 10.4m GTC spectroscopy of the galaxy 2" from the afterglow
- Konus-Wind detection of GRB 261010A
- GRB 261010A: Swift-BAT refined analysis
- GRB 261010A: NOT confirmation of the optical afterglow
- GRB 261010A: Fermi GBM Observation
- Explainer: what this is and why it matters (AI-written)
- GRB 261010A: Enhanced Swift-XRT position
- GRB 261010A: possible optical afterglow detected with the 1.5m OSN
- GRB 261010A: NOT possible optical counterpart
- GRB 261010A: Swift detection of a burst