GRB 170307A
GCN Circular 20880
Subject
GRB 170307A: 15 GHz upper limit from AMI
Date
2017-03-16T15:14:11Z (9 years ago)
From
Kunal Mooley at Oxford U <kunal.mooley@physics.ox.ac.uk>
K. P. Mooley, T. D. Staley, R. P. Fender (Oxford), G. E. Anderson
(Curtin), T. Cantwell (Manchester), D. Titterington, S. H. Carey, J.
Hickish, Y. C. Perrott, N. Razavi-Ghods, P. Scott (Cambridge), K.
Grainge, A. Scaife (Manchester)
We observed the GRB 170307A detected by Swift (Lien et al., GCN 20832,
Stamatikos et al. GCN 20838) and Fermi (Hui et al. GCN 20835) with the
AMI Large Array at 15 GHz on 2016 Mar 13.57 (UT). We place a 3sigma
upper limit of 90 uJy on the radio afterglow.
We thank the AMI staff for scheduling this observation. The AMI-GRB
database is a log of all GRB follow up observations with the AMI, and is
available at http://4pisky.org/ami-grb/.
GCN Circular 20838
Subject
GRB 170307A (trigger 741528): Swift-BAT refined analysis
Date
2017-03-08T13:59:24Z (9 years ago)
From
Amy Lien at GSFC <amy.y.lien@nasa.gov>
M. Stamatikos (OSU), S. D. Barthelmy (GSFC),
J. R. Cummings (CPI), N. Gehrels (GSFC),
H. A. Krimm (NSF/USRA), A. Y. Lien (GSFC/UMBC),
C. B. Markwardt (GSFC), D. M. Palmer (LANL),
T. Sakamoto (AGU), T. N. Ukwatta (LANL)
(i.e. the Swift-BAT team):
Using the data set from T-12 to T+963 sec from the recent telemetry downlink,
we determine that BAT trigger #741528 (Lien et al., GCN Circ. 20832) is indeed
a GRB, which also detected by Fermi GBM (Hui et al., GCN Circ. 20835). We report
further analysis of BAT GRB 170307A (trigger #741528).
The BAT ground-calculated position is
RA, Dec = 13.510, 9.538 deg which is
RA(J2000) = 00h 54m 02.5s
Dec(J2000) = +09d 32' 17.9"
with an uncertainty of 2.5 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 43%.
The mask-weighted light curve shows a weak structure with several overlapping
pulses that starts at ~T+55 s and ends at ~T+125 s. The burst emission might
start before it came into the BAT FOV at ~T-12 s. T90 (15-350 keV) is
56.92 +- 27.40 sec (estimated error including systematics).
The time-averaged spectrum from T+55.33 to T+124.69 sec is best fit by a simple
power-law model. The power law index of the time-averaged spectrum is
1.88 +- 0.23. The fluence in the 15-150 keV band is 1.3 +- 0.2 x 10^-6 erg/cm2.
The 1-sec peak photon flux measured from T+69.72 sec in the 15-150 keV band
is 1.4 +- 0.3 ph/cm2/sec. All the quoted errors are at the 90% confidence
level.
The results of the batgrbproduct analysis are available at
http://gcn.gsfc.nasa.gov/notices_s/741528/BA/
GCN Circular 20835
Subject
GRB 170307A: Fermi GBM observation
Date
2017-03-08T05:44:32Z (9 years ago)
From
C. Michelle Hui at MSFC/Fermi-GBM <c.m.hui@nasa.gov>
C.M. Hui (NASA/MSFC) and O.J. Roberts (USRA/NASA)
report on behalf of the Fermi GBM Team:
At 20:25:17.49 UT on 07 March 2017, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 170307A (trigger 510611122 /170307851),
which was also detected by Swift BAT (A. Y. Lien et al., GCN 20832).
The GBM on-ground location is consistent with the Swift position.
The angle from the Fermi LAT boresight at the GBM trigger time
using the Swift-BAT location is 98 degrees.
The GBM light curve consists of multiple peaks with a duration (T90)
of about 57.9s (50-300 keV). The time-averaged spectrum
from T0-27.6s to T0+28.7 s is adequately fit by a power law function
with an exponential high-energy cutoff. The power law index
is -1.18 +/- 0.26 and the cutoff energy, parameterized as Epeak,
is 83.80 +/- 19.90 keV.
The event fluence (10-1000 keV) in this time interval is
(1.85 +/- 0.25)E-06 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+8.3 s in the 10-1000 keV band is
1.72 +/- 0.25 ph/s/cm^2.
The spectral analysis results presented above are preliminary;
final results will be published in the GBM GRB Catalog.