Gamma-ray Burst 150127A
(All information courtesy of the instrument teams.)
Previous IAU Circulars
Results of Observations
- GCN Circular #17355
Matthew Stanbro (UAH) and A. von Kienlin (MPE)
report on behalf of the Fermi GBM Team:
"At 09:32:44.14 UT on 27 January 2015, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 150127A (trigger 444043967 / 150127398).
The on-ground calculated location, using the GBM trigger
data, is RA = 285.7, DEC = -8.4, with an uncertainty
of 2.8 degrees (radius, 1-sigma containment,
statistical only; there is additionally a systematic
error which is currently estimated to be 2 to 3 degrees).
The angle from the Fermi LAT boresight is 39 degrees.
The GBM light curve consists of several episodes
with a duration (T90) of about 53 s (50-300 keV).
The time-averaged spectrum from T0-0.00 s to T0+51.20 s is
best fit by a power law function with an exponential
high-energy cutoff. The power law index is -1.04 +/- 0.04 and
the cutoff energy, parameterized as Epeak, is 1478 +/- 225 keV.
A Band function fits the spectrum equally well
with Epeak= 1083 +/- 212 keV, alpha = -0.99 +/- 0.05 and beta = -2.21 +/- 0.23.
The event fluence (10-1000 keV) in this time interval is
(2.27 +/- 0.50)E-05 erg/cm^2. The 1-sec peak photon flux measured
starting from T0-0.32 s in the 10-1000 keV band
is 7.78 +/- 0.33 ph/s/cm^2.
The spectral analysis results presented above are preliminary;
final results will be published in the GBM GRB Catalog."
- GCN Circular #17356
J. L. Racusin (NASA/GSFC), G. Vianello (Stanford), and D. Kocevski
(NASA/GSFC) report on behalf of the Fermi-LAT team:
At 09:32:44 on January 27, 2015, Fermi-LAT detected emission from
GRB 150127A, which was also detected by Fermi-GBM (trigger
444043967/150127398, GCN 17355).
The GBM location was initially inside the LAT field of view at an angle
of ~39 degrees to the LAT boresight. No significant excess is seen
using standard analysis procedures >100 MeV.
Using the LAT Low Energy (LLE) data selection, over 60 counts
above background were detected within a 10 s interval coinciding
with the time of the GBM emission. This data selection has
insufficient spatial resolution to provide a reliable LAT localization.
Since an excess of events were not seen using the standard
analysis selection, this detection is likely due to low energy
gamma-rays (below 100 MeV).
The Fermi LAT point of contact for this burst is
Judith Racusin (email@example.com).
The Fermi-LAT is a pair conversion telescope designed to cover
the energy band from 20 MeV to greater than 300 GeV.
It is the product of an international collaboration between
NASA and DOE in the U.S. and many scientific institutions
across France, Italy, Japan and Sweden.
- GCN Circular #17359
K. Hurley and J. Goldsten, on behalf of the MESSENGER NS GRB team,
I. G. Mitrofanov, D. Golovin, M. L. Litvak, and A. B. Sanin,
on behalf of the HEND-Odyssey GRB team,
S. Golenetskii, R. Aptekar, V. Pal'shin, D. Frederiks,
D. Svinkin, and T. Cline on behalf of the Konus-Wind team,
V. Connaughton, M. S. Briggs, C. Meegan, V. Pelassa,
and A. Goldstein, on behalf of the Fermi GBM team, and
W. Boynton, C. Fellows, K. Harshman, H. Enos, and R. Starr,
on behalf of the GRS-Odyssey GRB team, report:
The long-duration GRB 150127A has been detected by Fermi (GBM: Stanbro
and von Kienlin, GCN Circ. 17355; LAT (but not localized): Racusin et
al., GCN Circ. 17356), Konus-Wind, MESSENGER (GRNS), and Mars-Odyssey
(HEND), so far, at about 34364 s UT (09:32:44).
We have triangulated it to a preliminary, 3 sigma error box whose
RA(2000), deg Dec(2000), deg
296.953 (19h 47m 49s) -9.416 ( -9d 24' 58")
297.190 (19h 48m 46s) -6.883 ( -6d 52' 58")
296.956 (19h 47m 50s) -7.457 ( -7d 27' 25")
296.868 (19h 47m 28s) -13.764 (-13d 45' 49")
297.021 (19h 48m 05s) -12.130 (-12d 07' 50")
The error box area is 1.1 sq. deg, and its maximum
dimension is 6.9 deg (the minimum one is 11 arcmin).
The Sun distance was 13 deg.
This box may be improved.
A triangulation map is posted at
The Konus-Wind time history and spectrum will be given in forthcoming
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Jochen Greiner, last update: 07-Feb-2015