GRB 260317A
GCN Circular 45358
Subject
GRB 260317A: SVOM/ECLAIRs detection through offline targeted search and its possible association to magnetar 1E 1841-04.5
Date
2026-08-11T18:19:29Z (2 days ago)
Edited On
2026-08-12T13:07:23Z (a day ago)
From
SVOM_group <svomgroup@bao.ac.cn>
Edited By
Vidushi Sharma at NASA GSFC/UMBC <vidushi.sharma@nasa.gov> on behalf of SVOM_group <svomgroup@bao.ac.cn>
Via
Web form
H. Yang, O. Godet, S. Guillot, L. Bouchet, J.-L. Atteia (IRAP), T. Maiolino (LUMP), D. Turpin, S. Schanne (CEA)
report on behalf of the SVOM team:
The SVOM/ECLAIRs telescope detected GRB 260317A, also detected by Fermi/GBM (GCN 44041), starting at 2026-03-17T20:01:51.940 UTC (T0), through an offline targeted search with the event-by-event data downloaded via the X-band ground station.
The burst was detected within several timescales and energy ranges. The best detection is obtained by the image trigger with a signal-to-noise ratio of 5.4 within 8-50 keV over a time window of 0.04 s starting at T0. This event was not detected onboard because it was too faint and too short.
The ECLAIRs lightcurve shows a multi-peaked structure lasting around 0.04 s.
The localization of the source is RA, Dec =280.383, -5.301 degrees:
RA (J2000) = 18h41m32s
Dec (J2000) = -05d18m04s
with a 90% C.L. radius of 14.3 arcmin (including systematic error of 2 arcmin added in quadrature). This localization is broadly consistent with that reported by Fermi/GBM (GCN 44041). The angular separation between the two positions is 27.5 degrees, which is compatible with the 13.33 degrees 1-sigma statistical uncertainty of the GBM localization.
The time-averaged spectrum from T0 to T0+0.04 s in the 5-120 keV is well fitted by a power law with a photon index of 1.1+/-0.2 and a corresponding 4-120 keV fluence of (6+/-1)e-8 erg/cm^2.
Given the proximity (22 arcmin) of GRB 260317A to the magnetar 1E 1841-04.5 (also named PSR J1841−0456), and the possibly underestimated ECLAIRs positional uncertainties due to the very short duration of the burst, it is possible that GRB 260317A is actually a magnetar short burst.
All quoted errors are at the 68% confidence level.
The Space Variable Objects Monitor (SVOM) is a China-France joint mission led by the Chinese National Space Administration (CNSA), French Space Agency (CNES), and the Chinese Academy of Sciences (CAS), which is dedicated to observing gamma-ray bursts and other transient phenomena in the energetic universe. ECLAIRs was developed jointly by APC, CEA, CNES, and IRAP.
The SVOM/ECLAIRs point of contact for this event is : Hui Yang (hui.yang@cnrs.fr)
GCN Circular 44041
Subject
GRB 260317A: Fermi GBM Final Localization
Date
2026-03-17T21:55:00Z (5 months ago)
From
rhamburg@usra.edu
Via
Web form
The Fermi GBM team reports the detection of a likely SHORT GRB.
"At 20:01:51.98 UT on 17 March 2026, the Fermi Gamma-ray Burst Monitor (GBM)
triggered and located GRB 260317A (trigger 795470516/260317835).
The on-ground calculated location, using the Fermi GBM trigger data,
is RA = 255.62, Dec = -18.51 (J2000 degrees, equivalent to J2000 17h 2m, -18d 30'),
with a statistical uncertainty of 13.33 degrees.
The angle from the Fermi LAT boresight is 93 degrees.
The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260317835/quicklook/glg_skymap_all_bn260317835.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/bn260317835/quicklook/glg_healpix_all_bn260317835.fit
The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260317835/quicklook/glg_lc_medres34_bn260317835.gif"