GRB 261030A

A. Jameson (UAH) reports on behalf of the Fermi Gamma-ray Burst Monitor Team:

"At 16:27:22.28 UT on 30 October 2026, the Fermi Gamma-ray Burst Monitor (GBM)
triggered and located GRB 261030A (trigger 815070447/261030686).

The on-ground calculated location, using the Fermi GBM trigger data,
is RA = 340.59, Dec = 7.07 (J2000 degrees, equivalent to
J2000 22h 42m, +7d 4'), with a statistical uncertainty of 1.00 degrees.
(radius, 1-sigma containment, statistical only; there is additionally a
systematic error which we have characterized as a mixture of two Gaussians,
one with a radius of 1.8 degrees (52% contribution) and one with a radius
of 4.1 degrees (47% contribution) [A. Goldstein et al. 2020, ApJ, 895, 1]).

The angle from the Fermi LAT boresight is 74 degrees.

The GBM light curve consists of a single emission episode with a duration (T90)
of about 37 s (50-300 keV). The time-averaged spectrum
from T0-2.2 to T0+48.7 s is best fit by
a Band function with Epeak = 117.9 +/- 0.8 keV,
alpha = -1.080 +/- 0.002, and beta = -2 +/- 0.01.

The event fluence (10-1000 keV) in this time interval is
(2.29 +/- 0.02)E-05 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+18 s in the 10-1000 keV band is 11.7 +/- 0.3 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/"

T. Preis (University of Innsbruck) & J. Greiner (MPE Garching) report:

The public trigdat data of the Fermi Gamma-ray Burst Monitor (GBM) trigger
815070447 at 16:27:22 on 30 Oct. 2026 were automatically fitted for spectrum
and sky location with BALROG (Burgess et al. 2018, MNRAS 476, 1427;
Berlato et al. 2019, ApJ 873, 60).

The best-fit position is:
RA(2000.0) = 341.2 deg
Decl.(2000.0) = 7.5 deg
The 1 sigma statistical error radius is 1.7 deg.
We estimate an additional systematic error of 2 deg.

Further details are available at:
https://grb.mpe.mpg.de/grb/GRB261030686/

The Healpix map can be downloaded from:
https://grb.mpe.mpg.de/grb/GRB261030686/healpix

The location parameters are available as JSON at:
https://grb.mpe.mpg.de/grb/GRB261030686/json

                        

The Fermi GBM team reports the detection of a likely LONG GRB

At 16:27:22 UT on 30 Oct 2026, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 261030A (trigger 815070447.276984 / 261030686).

The on-ground calculated location, using the Fermi GBM trigger data, is RA = 340.6, Dec = 7.1 (J2000 degrees, equivalent to J2000 22h 42m, 7d 05'), with a statistical uncertainty of 1.0 degrees.

The angle from the Fermi LAT boresight is 74.0 degrees.

The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn261030686/quicklook/glg_skymap_all_bn261030686.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/bn261030686/quicklook/glg_healpix_all_bn261030686.fit

The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn261030686/quicklook/glg_lc_medres34_bn261030686.gif