GRB 260608A
GCN Circular 44886
Subject
GRB 260608A: Fermi GRB Observation
Date
2026-06-09T16:34:28Z (11 days ago)
From
Padraig McDermott at University College Dublin <padraig.mcdermott@ucdconnect.ie>
Via
Web form
Padraig Mc Dermott (UCD) and C. Meegan (UAH) report on behalf of
the Fermi Gamma-ray Burst Monitor Team:
"At 11:35:31.06 UT on 08 June 2026, the Fermi Gamma-ray Burst Monitor (GBM)
triggered and located GRB 260608A (trigger 802611336/260608483).
which was also detected by SVOM ECLAIRs (M.Brunet et al. 2026, GCN 44870, GCN 44882).
The Fermi GBM on-ground location is consistent with the SVOM ECLAIRs position.
The angle from the Fermi LAT boresight is 31 degrees.
The GBM light curve consists of a main emission followed by a smaller peak with a duration (T90)
of about 50 s (50-300 keV). The time-averaged spectrum
from T0-6.7 to T0+43.6 s is best fit by
a power law function with an exponential high-energy cutoff.
The power law index is -1.35 +/- 0.02 and the cutoff energy,
parameterized as Epeak, is 93 +/- 3 keV.
The event fluence (10-1000 keV) in this time interval is
(2.83 +/- 0.11)E-06 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+0.83 s in the 10-1000 keV band is 2.1 +/- 0.2 ph/s/cm^2.
The spectral analysis results presented above are preliminary;
final results will be published in the GBM GRB Catalog:
https://heasarc.gsfc.nasa.gov/W3Browse/fermi/fermigbrst.html
For Fermi GBM data and info, please visit the official Fermi GBM Support Page:
https://fermi.gsfc.nasa.gov/ssc/data/access/gbm/"
GCN Circular 44882
Subject
GRB 260608A: SVOM/ECLAIRs refined analysis
Date
2026-06-09T11:54:47Z (11 days ago)
From
SVOM_group <svomgroup@bao.ac.cn>
Via
Web form
M. Brunet, L. Bouchet (IRAP), C.-W. Wang (IHEP) D.-F. Kong (GXU) report on behalf of the SVOM/ECLAIRs team:
Using the event-by-event data downloaded through the X-band ground station, we report further analysis of SVOM/ECLAIRs observations of GRB 260608A (SVOM burst-id sb260608A – GCN 44870, trigger time T0 = 2026-06-08T11:35:32 UTC), which was also detected by Fermi/GBM (GCN 44868).
The burst that triggered ECLAIRs onboard shows a multiple peak lightcurve. The burst duration is T90 = 57.4 +3.8/-2.6 s in the 4-120 keV energy band.
The time-averaged spectrum from T0-5.2 s s to T0+52.0 s in the 5-120 keV energy range is best fitted by a powerlaw model with alpha = -1.51 +/- 0.04. With this model, the 4-120 keV fluence is (3.1 +/- 0.1)e-6 erg/cm^2 and the 4-120 keV photon flux is 1.55 +/- 0.04 ph/cm^2/s.
All the quoted errors are at the 68% confidence level.
The Space-based multi-band astronomical 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 CNES, CEA-IRFU, CNRS-IRAP, CNRS-APC.
The SVOM/ECLAIRs point of contact for this burst is: Marius Brunet (IRAP) (marius.brunet at utoulouse.fr)
GCN Circular 44870
Subject
GRB 260608A: SVOM detection of a burst
Date
2026-06-08T12:08:17Z (12 days ago)
From
SVOM_group <svomgroup@bao.ac.cn>
Via
Web form
M. Brunet, L. Bouchet (IRAP), C.-W. Wang (IHEP) D.-F. Kong (GXU) report on behalf of the SVOM mission team:
At 2026-06-08T11:35:32 UTC (T0), SVOM/ECLAIRs triggered and located the gamma-ray burst GRB 260608A (SVOM burst-id sb26060803), which is also detected by Fermi/GBM (GCN 44868).
The following trigger information was received on the ground with low latency by the SVOM VHF Alert Network.
The burst was detected both by the Count-Rate Trigger (CRT) and the Image Trigger (IMT), which produced a sequence of 34 alerts. IMT provided the alert with the best signal-to-noise-ratio in the image (SNR) of 24.71 in the [8-120] keV energy band over a time window of 81.92 seconds starting at 2026-06-08T11:35:14.
The localization of the best alert is R.A., Dec. 81.3711, -48.3879 degrees:
R.A. (J2000) = 5h25m29.07s
Dec. (J2000) = -48d23m16.62s
with a 90% confidence level (C.L.) radius of 3.70 arcmin (including systematic error of 2 arcmin added in quadrature).
TThe SVOM/ECLAIRs light curve showed a multiple peak structure with a T90 duration of about 46.839 (-2.959 +3.411) s.
This burst was also detected by SVOM/GRM with a significance of 18.20.
The SVOM/GRM light curve showed a multiple peak structure with a T90 duration of about 53.73 (-2.457 +2.459) s.
The SVOM/GRM light curve can be found here:
https://www.bursthub.cn//admin/static/svgrb260608A.png
Due to Sun constraint, no X-ray observation could be performed by SVOM/MXT and no optical observation could be performed by SVOM/VT for the time being.
The Space-based multi-band astronomical 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. SVOM/ECLAIRs was developed jointly by CNES, CEA-IRFU, CNRS-IRAP, CNRS-APC. SVOM/GRM was developed by the Institute of High Energy Physics (IHEP) of CAS. SVOM/MXT was developed jointly by CNES, CEA-IRFU, CNRS-IJCLab, University of Leicester, MPE.
The Burst Advocate (BA) on shift for this alert is Chenwei Wang: cwwang@ihep.ac.cn
Please contact the BA by email if you require additional information.
GCN Circular 44869
Subject
GRB 260608A: Fermi GBM Final Real-time Localization (duplicate submission)
Date
2026-06-08T11:47:57Z (12 days ago)
Edited On
2026-06-10T15:54:52Z (10 days ago)
From
Fermi GBM Team at MSFC/Fermi-GBM <do_not_reply@GIOC.nsstc.nasa.gov>
Edited By
Judith Racusin at NASA/GSFC <judith.racusin@nasa.gov>
Via
email
GCN Circular 44868
Subject
GRB 260608A: Fermi GBM Final Real-time Localization
Date
2026-06-08T11:46:30Z (12 days ago)
From
Fermi GBM Team at MSFC/Fermi-GBM <do_not_reply@GIOC.nsstc.nasa.gov>
Via
email
The Fermi GBM team reports the detection of a likely LONG GRB
At 11:35:31 UT on 8 Jun 2026, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 260608A (trigger 802611336.05914 / 260608483).
The on-ground calculated location, using the Fermi GBM trigger data, is RA = 78.4, Dec = -45.2 (J2000 degrees, equivalent to J2000 05h 13m, -45d 12'), with a statistical uncertainty of 3.2 degrees.
The angle from the Fermi LAT boresight is 29.0 degrees.
The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260608483/quicklook/glg_skymap_all_bn260608483.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/bn260608483/quicklook/glg_healpix_all_bn260608483.fit
The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260608483/quicklook/glg_lc_medres34_bn260608483.gif