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GRB 260614B

GCN Circular 45063

Subject
GRB 260614B: ATCA Radio Upper Limits
Date
2026-07-01T14:14:22Z (4 months ago)
From
Sarah Chastain at Texas Tech University <sarahichastain@gmail.com>
Via
Web form

S. I. Chastain (TTU), G. E. Anderson (CSIRO), S. Ryder (Macquarie), A. Gulati (USyd), A. J. van der Horst (GWU), J. K. Leung (UofT/HUJI), and L. Rhodes (TSI/McGill) on behalf of the ATCA PanRadio GRB collaboration:

We observed the long GRB 260614B detected by SVOM (SVOM Team, GCN 44938) and Fermi-GBM (Fermi GBM Team, GCN 44937) with the Australia Telescope Compact Array (ATCA) 6.4 and 11.5 days post-burst.

No radio source was detected within the SVOM VT localization region (SVOM Team, 44939). At 8 GHz we find 3-sigma upper limits of 27 and 48 microJy/beam, at 6.4 and 11.5 days post-burst respectively.

We thank the CSIRO Space and Astronomy staff for supporting these observations.
We acknowledge the Gomeroi people as the traditional owners of the Observatory site. The Australia Telescope Compact Array is part of the Australia Telescope National Facility (https://ror.org/05qajvd42) which is funded by the Australian Government for operation as a National Facility managed by CSIRO.

GCN Circular 45019

Subject
GRB 260614B: EP-FXT follow-up observation
Date
2026-06-22T22:10:22Z (4 months ago)
From
SVOM_group <svomgroup@bao.ac.cn>
Via
Web form
M. Pillas (IAP), A. Saccardi (CEA/Irfu), Ziming Wang (PKU), report on behalf of the SVOM and EP collaborations:

EP-FXT performed a follow-up observation of GRB 260614B detected by SVOM/ECLAIRs (Godet et al., GCN 44938). The follow-up observation started on 2026-06-15 at 15:05:04 (UTC), about 25.3 hr after the SVOM trigger, with a total exposure time of 4 ks.

On-ground analysis of the FXT data found an uncatalogued source within the ECLAIRs and MXT error circles at R.A., Dec. = 353.9080, -54.1164 deg (J2000) with an uncertainty of about 10 arcsec (radius, 90% C.L. statistical and systematic). This position is consistent with the optical counterpart (Palmerio et al., GCN 44939; Li et al., GCN 44943). The derived average unabsorbed flux is (1.64 +/- 0.25) x 10^(-13) erg/s/cm^2 (0.5-10 keV; 1-sigma uncertainty).

Launched on January 9, 2024, EP is a space X-ray observatory to monitor the soft X-ray sky with X-ray follow-up capability (Yuan et al. 2022, Handbook of X-ray and Gamma-ray Astrophysics).

GCN Circular 44986

Subject
GRB 260614B: NuSTAR detection of prompt emission
Date
2026-06-19T03:32:52Z (4 months ago)
From
Gaurav Waratkar at Caltech <gauravwaratkar@iitb.ac.in>
Via
Web form
G. Waratkar (Caltech) and B. Grefenstette (Caltech) report on behalf of the NuSTAR Search for INteresting Gamma-ray Signals (SINGS) working group:

The NuSTAR SINGS working group reports the detection of prompt emission from the long-duration GRB 260614B in both the NuSTAR CsI anti-coincidence shields. Details of the search algorithm will be described in a future paper.

The NuSTAR SINGS algorithm, triggered at 2026-06-14T13:49:47.0 UTC, shows a detection of GRB 260614B, also detected by Fermi-GBM (Fermi GBM Team, GCN 44937), SVOM (Godet et al., GCN 44938), and GECAM-B (Luo et al., GCN 44945).

The NuSTAR CsI shield data are recorded at 1 Hz. We detect a burst lasting for about 20-s, consistent with the Fermi and GECAM-B lightcurve. The peak count rate is ~1500-cps with a baseline rate of ~1000-cps during this time period. We do not see any evidence in the signal above 100 keV in the CZT detectors.

The SVOM/VT counterpart (Palmerio et al., GCN 44939) at RA = 353.90883, Dec = -54.11628 implies an offset from the NuSTAR boresight of 99-deg (i.e. from the side) and an offset from the geocenter of 125-deg.

Lightcurves and analysis for this GRB can be found here:
https://nustarsoc.caltech.edu/NuSTAR_Public/grbs/reports/2026/260614B 

Information on NuSTAR SINGS can be found here: 
https://nustarsoc.caltech.edu/NuSTAR_Public/grbs/     

NuSTAR is a NASA Small Explorer mission led by Caltech and managed by JPL for NASA's Science Mission Directorate in Washington.

GCN Circular 44947

Subject
GRB 260614B: SVOM/ECLAIRs refined analysis
Date
2026-06-15T21:03:45Z (4 months ago)
From
SVOM_group <svomgroup@bao.ac.cn>
Via
Web form
M. Brunet, O. Godet, S. Guillot (IRAP), M. Pillas (IAP) 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 260614B (SVOM burst-id sb26061401 – GCN 44938, trigger time T0 = 2026-06-14T13:49:55 UTC), which was also detected by Fermi/GBM (GCN 44937, 44942) and GECAM-B (GCN 44945). 

The burst that triggered ECLAIRs onboard shows a multiple peak lightcurve. The burst duration is T90 = 88 +18/-9 s in the 4-120 keV energy band.

The time-averaged spectrum before the slew from T0-4 s to T0+37 s in the 5-120 keV energy range is best fitted by a powerlaw model with a photon index of -1.04 +/- 0.03. With this model, the 4-120 keV fluence is (5.4 +/- 0.1)e-6 erg/cm^2 and the 4-120 keV photon flux is 2.50 +0.04/-0.06 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 44945

Subject
GRB 260614B: GECAM-B observation
Date
2026-06-15T08:39:27Z (4 months ago)
From
Xinghao Luo at IHEP <2952704891@qq.com>
Via
Web form
Xing-Hao Luo, Chen-Wei Wang, Shao-Lin Xiong (IHEP) report on behalf of GECAM team:

GECAM-B was triggered in-flight by GRB 260614B, at 2026-06-14T13:49:54.950 UTC (denoted as T0), which is also detected by Fermi/GBM (Fermi GBM team, GCN #44937), and SVOM/ECLAIRs (O. Godet et.al., GCN#44938).

According to the GECAM-B light curves in about 70-6000 keV, this burst mainly consists of multiple pulses with a duration (T90) of 43 +/-7 s.

The GECAM-B light curve can be found here:
https://www.bursthub.cn//admin/static/gecambgrb260614B.png

In addition, the position of this burst is determined by SVOM/VT (RA=353.90883 , DEC=-54.11628, with an uncertainty of 0.50 arcsec, J.T. Palmerio et.al., GCN #44939). With this localization, the time-averaged spectrum from T0-19.5 to T0+22.5 s is best fitted by a power law function. The power law index is -1.58 +0.08/-0.09. The event fluence (10-1000keV) in this time interval is (2.43 +0.17/-0.16)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).

GCN Circular 44943

Subject
GRB 260614B: SVOM/VT optical afterglow confirmation
Date
2026-06-15T01:08:34Z (4 months ago)
Edited On
2026-06-15T18:41:43Z (4 months ago)
From
Huali Li at at NAOC, SVOM <lhl@nao.cas.cn>
Edited By
Vidushi Sharma at NASA GSFC/UMBC <vidushi.sharma@nasa.gov> on behalf of Huali Li at at NAOC, SVOM <lhl@nao.cas.cn>
Via
Web form
H. L. Li, L. P. Xin, Y. L. Qiu, C. Wu, J. R. Xu, Y. N. Ma, Z. H. Yao, X. H. Han, J. Wang, Y. Xu, P. P. Zhang, W. J. Xie, Y. J. Xiao, H. B. Cai, J. S. Deng, J. Y. Wei (NAOC), J. T. Palmerio (CEA/Irfu), O. Godet (IRAP) and M. Pillas (IAP) report on behalf of the SVOM/VT team.

SVOM/VT performed observations with an automatic slew of GRB 260614B triggered by SVOM/ECLAIRs (sb26061401, Godet et al., GCN 44938), which was also detected by SVOM/GRM (Godet et al., GCN 44938) and Fermi GBM (the Fermi GBM team, GCN 44937; Palafox, GCN 44942). The observation started at 2026-06-14T13:52:36 UTC, i.e., 186 seconds post trigger in the VT_B (400-650 nm) and VT_R (650-1000 nm) channels simultaneously.

The optical counterpart identified via VT VHF data (Palmerio et al., GCN 44939) within the error box of SVOM/ECLAIRs and SVOM/MXT (Godet et al., GCN 44938) is clearly detected in both channels. The following measurements are in the AB magnitude and are not corrected for Galactic extinction:

Mid time | Band | Exposure Time | Brightness
186 s      VT_B        50 s       18.28 +/-0.05 mag
186 s      VT_R        50 s       15.56 +/-0.04 mag
3.16 h     VT_B    20*100 s        23.0 +/-0.2  mag
3.10 h     VT_R    16*100 s        20.3 +/-0.1  mag

The source showed a fading slope of about -1.2 during the observations above.

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 Circular 44942

Subject
GRB 260614B: Fermi GBM Observation
Date
2026-06-14T21:57:48Z (4 months ago)
From
Eva M. Palafox at INAOE <eva.palafox@gmail.com>
Via
Web form
E. Palafox (INAOE-Mexico) reports on behalf of the Fermi Gamma-ray Burst Monitor Team:

"At 13:49:53.52 UT on 14 June 2026, the Fermi Gamma-ray Burst Monitor (GBM)
triggered and located GRB 260614B (trigger 803137798/260614576).
which was also detected by SVOM/ECLAIRs (Godet et al. 2026, GCN 44938).
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 single emission episode with a duration (T90)
of about 30 s (50-300 keV). The time-averaged spectrum
from T0-13 to T0+34 s is best fit by
a power law function with an exponential high-energy cutoff.
The power law index is -0.78 +/- 0.03 and the cutoff energy,
parameterized as Epeak, is 510 +/- 10 keV.

The event fluence (10-1000 keV) in this time interval is
(2.20 +/- 0.04)E-05 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+13 s in the 10-1000 keV band is 5.7 +/- 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 44939

Subject
GRB 260614B: SVOM/VT optical candidate from VHF data
Date
2026-06-14T15:06:45Z (4 months ago)
From
SVOM_group <svomgroup@bao.ac.cn>
Via
Web form

J. T. Palmerio, A. Saccardi (CEA/Irfu), Y. L. Qiu, C. Wu, L. P. Xin (NAOC), M. Pillas (IAP) on behalf of the SVOM/VT team.

After the trigger by SVOM/ECLAIRs at 2026-06-14T13:49:55 UTC (T0), SVOM performed an automatic slew on the burst location (Godet et al., GCN 44938

Loading...
 
 
). SVOM/VT began observing the field in the VT_B (400nm-650nm) and VT_R (650nm-1000nm) channels simultaneously.

From a preliminary analysis of the 1-bit subimage and source list downloaded via VHF network, at least one credible candidate is identified, the details of which are presented below.

VT_ID 52: The position of this candidate is R.A., Dec. 353.90883, -54.11628 degrees, corresponding to:

R.A. (J2000) = 23h35m38.1s

Dec. (J2000) = -54d06m58.6s

with an uncertainty of 0.50 arcsec.

This candidate was detected in both VT_R and VT_Band was flagged as an uncatalogued source. The candidate's magnitudes are:

date-obs (UTC)mid-timeexposureVT_B mag(AB)VT_R mag(AB)
2026-06-14T13:54:162026-06-14T13:56:466x50s19.25 ± 0.0116.35 ± 0.01
2026-06-14T13:59:162026-06-14T14:01:215x50s–16.71 ± 0.01

Magnitudes were not corrected for Galactic reddening.

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/VT was jointly developed by Xi'an Institute of Optics and Precision Mechanics (XIOPM), CAS and National astronomical observatories (NAOC), CAS.

The Burst Advocate (BA) on shift for this alert is Marion Pillas: marion.pillas@iap.fr. Please contact the BA by email if you require additional information.

GCN Circular 44938

Subject
GRB 260614B: SVOM detection of a burst
Date
2026-06-14T14:17:03Z (4 months ago)
Edited On
2026-06-14T21:04:00Z (4 months ago)
From
SVOM_group <svomgroup@bao.ac.cn>
Edited By
Judith Racusin at NASA/GSFC <judith.racusin@nasa.gov> on behalf of SVOM_group <svomgroup@bao.ac.cn>
Via
Web form
O. Godet (IRAP), M. Pillas (IAP), D. Götz (CEA), F. Robinet (IJCLAB)  report on behalf of the SVOM mission team:

At 2026-06-14T13:49:55 UTC (T0), SVOM/ECLAIRs triggered and located the gamma-ray burst GRB 260614B (SVOM burst-id sb26061401), also detected by Fermi/GBM (GCN #44937).

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 15 alerts. IMT provided the alert with the best signal-to-noise-ratio in the image (SNR) of 40.78 in the [8-120] keV energy band over a time window of 20.48 seconds starting at 2026-06-14T13:49:52.

The localization of the best alert is R.A., Dec. 353.940, -54.154 degrees:
R.A. (J2000) = 23h35m45.60s
Dec. (J2000) = -54d09m13.40s
 with a 90% confidence level (C.L.) radius of 2.75 arcmin (including systematic error of 2 arcmin added in quadrature).

The SVOM/ECLAIRs light curve showed a multiple broad peak structure with a T90 duration of about 19.62 -2.19 / +5.93 s (5-120 keV).

This burst also triggered SVOM/GRM at 2026-06-14T13:49:47 on a timescale of 4 seconds with an SNR of 5.10.

The SVOM/GRM light curve showed a single/multiple broad/narrow peak structure with a T90 duration of about 35.48 -2.25 / +3.70 (8-1100 keV).

SVOM slewed to the burst.

SVOM/MXT began observing the field at 2026-06-14T13:52:24.0 UTC. Using onboard processed data we found an uncatalogued X-ray source located at R.A., Dec. 353.907,  -54.1192 degrees with a 90% C.L. radius of 69 arcseconds.

This location is 2.39 arcminutes from the ECLAIRs onboard position. This position may be improved as more data is received.

VT began observing the field after the slew. The analysis of the data will be published in a future circular.

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 Marion Pillas: marion.pillas@iap.fr.
Please contact the BA by email if you require additional information.

GCN Circular 44937

Subject
GRB 260614B: Fermi GBM Final Real-time Localization
Date
2026-06-14T13:57:42Z (4 months 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 13:49:53 UT on 14 Jun 2026, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 260614B (trigger 803137798.515116 / 260614576).

The on-ground calculated location, using the Fermi GBM trigger data, is RA = 2.5, Dec = -50.9 (J2000 degrees, equivalent to J2000 00h 10m, -50d 53'), with a statistical uncertainty of 2.7 degrees.

The angle from the Fermi LAT boresight is 25.0 degrees.

The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260614576/quicklook/glg_skymap_all_bn260614576.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/bn260614576/quicklook/glg_healpix_all_bn260614576.fit

The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260614576/quicklook/glg_lc_medres34_bn260614576.gif
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