GRB 160225B
GCN Circular 19095
Subject
IPN Triangulation of GRB 160225B
Date
2016-02-26T21:45:56Z (9 years ago)
From
Dmitry Svinkin at Ioffe Institute <svinkin@mail.ioffe.ru>
D. Svinkin, S. Golenetskii, R. Aptekar, D. Frederiks, A. Kozlova,
and T. Cline on behalf of the Konus-Wind team,
K. Hurley, on behalf of the IPN,
V. Connaughton, M. S. Briggs, C. Meegan, V. Pelassa,
and A. Goldstein, on behalf of the Fermi GBM team,
A. von Kienlin, X. Zhang, A. Rau, V. Savchenko, E. Bozzo,
and C. Ferrigno, on behalf of the INTEGRAL SPI-ACS GRB team, and
S. Barthelmy, J. Cummings, N. Gehrels, H. Krimm, and D. Palmer,
on behalf of the Swift-BAT team, report:
The long-duration GRB 160225B has been detected by Fermi (GBM; trigger
478121069), Konus-Wind, INTEGRAL (SPI-ACS), Swift (BAT), so far, at
about 69865 s UT (19:24:25). The burst was outside the coded field of
view of the BAT.
We have triangulated it to a preliminary annulus centered
at RA(2000)=174.671 deg (11h 38m 41s) Dec(2000)=+0.848 deg (+0d 50'
52"), whose radius is 43.602 +/- 8.004 deg (3 sigma). The minimum
distance between the center line of this annulus and the MASTER-NET
optical transient (Buckley, et al., GCN Circ. 19092 and 19094) is 19.5
arcmin, so the association of the OT and the GRB cannot be ruled out
based on the triangulation only.
A triangulation map is posted at
http://www.ioffe.ru/LEA/GRBs/GRB160225_T69916/IPN/
The time history and spectrum will be given in forthcoming GCN Circulars.
GCN Circular 19096
Subject
GRB 160225B: Fermi GBM detection
Date
2016-02-26T23:54:49Z (9 years ago)
From
C. Michelle Hui at MSFC/Fermi-GBM <c.m.hui@nasa.gov>
C. M. Hui (NASA/MSFC), E. Burns (UAH), and C. Meegan (UAH)
reports on behalf of the Fermi GBM Team:
At 19:24:25.39 UT on 25 February 2016, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 160225B (trigger 478121069 / 160225809)
which was also triangulated by IPN (Svinkin et al., GCN 19095)
The on-ground calculated location, using the GBM trigger data,
is RA = 150.19 , DEC = -34.71 (J2000 degrees,
equivalent to 10h 00m, -34d 42.0'), with an uncertainty of 1.00 degrees
(radius, 1-sigma containment, statistical only; there is additionally
a systematic error which we have characterized as a core-plus-tail model,
with 90% of GRBs having a 3.7 deg error and a small tail suffering
a larger than 10 deg systematic error.
[Connaughton et al. 2015, ApJS, 216, 32]).
The angle from the Fermi LAT boresight is 100 degrees.
The GBM light curve shows two peaks
with a duration (T90) of about 64 s (50-300 keV).
The time-averaged spectrum from T0+43.009 s to T0+74.753 s is
best fit by a power law function with an exponential
high-energy cutoff. The power law index is -0.91 +/- 0.03 and
the cutoff energy, parameterized as Epeak, is 124.10 +/- 3.30 keV.
The event fluence (10-1000 keV) in this time interval is
(1.434 +/- 0.023)E-05 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+54.27 s in the 10-1000 keV band is 12.89 +/- 0.37 ph/s/cm^2.
The spectral analysis results presented above are preliminary;
final results will be published in the GBM GRB Catalog.