GRB 161015A
GCN Circular 20054
Subject
GRB 161015A: Fermi-LAT detection
Date
2016-10-16T02:25:49Z (9 years ago)
From
Masanori Ohno at Hiroshima U <ohno@hep01.hepl.hiroshima-u.ac.jp>
Masanori Ohno (Hiroshima Univ.), E. Bissaldi (Politecnico & INFN Bari), J.
E. McEnery (NASA/GSFC), M. Arimoto (Tokyo Tech) and G. Vianello (Stanford)
report on behalf of the Fermi-LAT team:
At 17:03:07.04 on October, 15, 2016 Fermi-LAT detected high-energy emission
from GRB 161015A, which was also detected by Fermi-GBM (trigger 498243790 /
161015710).
The best LAT on-ground location is found to be
RA, Dec = 269.15, 30.19 (J2000)
with an error radius of 0.21 deg (90 % containment, statistical error
only).
This was 50 deg from the LAT boresight at the time of the trigger and
triggered an autonomous repoint of the spacecraft.
The data from the Fermi-LAT show a significant increase in the event rate
that is spatially and temporally correlated with the trigger with high
significance.
The highest-energy photon is a 1.5 GeV event which is observed 72 seconds
after the GBM trigger.
A Swift ToO has been requested for this burst.
The Fermi-LAT point of contact for this burst is Masanori Ohno (
ohno@hep01.hepl.hiroshima-u.ac.jp)
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 20055
Subject
GRB 161015A: Tiled Swift observations
Date
2016-10-16T03:46:29Z (9 years ago)
From
Phil Evans at U of Leicester <pae9@leicester.ac.uk>
P. A. Evans (U. Leicester) reports on behalf of the Swift team:
Swift has initiated a series of observations, tiled on the sky, of the
Fermi/LAT GRB 161015A. Automated analysis of the XRT data will
be presented online at http://www.swift.ac.uk/xrt_products/TILED_GRB00059
Any uncatalogued X-ray sources detected in this analysis will be
reported on this website and via GCN COUNTERPART notices. The probability of finding
serendipitous sources, unrelated to the Fermi/LAT event is high: any X-ray source
considered to be a probable afterglow candidate will be reported via a GCN Circular
after manual consideration.
Details of the XRT automated analysis methods are detailed in Evans et
al. (2007, A&A, 469, 379; 2009, MNRAS, 397, 1177 and 2014, ApJS, 210, 8).
This circular is an official product of the Swift-XRT team.
GCN Circular 20056
Subject
GRB 161015A: Fermi GBM detection
Date
2016-10-16T04:08:41Z (9 years ago)
From
Matthew Stanbro at UAH/Fermi <mcs0001@uah.edu>
M Stanbro (UAH) and C Meegan (UAH)
report on behalf of the Fermi GBM Team:
"At 17:03:07.03 UT on 15 October 2016, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 161015A (trigger 498243791 / 161015710),
which was also detected by the Fermi-LAT
(Masanori Ohno et al. 2016, GCN 20054)
The GBM on-ground location is consistent with the Fermi-LAT position.
The GBM light curve consists of 3 episodes
with a duration (T90) of about 15 s (50-300 keV).
The time-averaged spectrum from T0-0.003 s to T0+16.384 s is
best fit by a Band function with Epeak = 151 +/- 9 keV,
alpha = -0.82 +/- 0.05, and beta = -2.32 +/- 0.11.
The event fluence (10-1000 keV) in this time interval is
(1.17 +/- 0.03)E-05 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+2.24 s in the 10-1000 keV band
is 10.58 +/- 0.30 ph/s/cm^2.
A power law function with an exponential
high-energy cutoff fits the spectrum equally well
with Epeak= 183 +/- 7 keV, alpha = -0.93 +/- 0.03.
The spectral analysis results presented above are preliminary;
final results will be published in the GBM GRB Catalog."
--
Matthew C. Stanbro
Fermi GBM Graduate Research Assistant
University of Alabama in Huntsville
GCN Circular 20057
Subject
GRB 161015A: Swift-XRT observations
Date
2016-10-16T15:11:23Z (9 years ago)
From
Paolo D'Avanzo at INAF-OAB <paolo.davanzo@brera.inaf.it>
P. D'Avanzo, A. Melandri (INAF-OAB), P. A. Evans (U. Leicester),
report on behalf of the Swift-XRT team:
Swift-XRT has performed follow-up observations of the Fermi/LAT-detected
burst GRB 161015A (Masanori Ohno et al., GCN 20054; Stanbro & Meegan,
GCN Circ. 20056) in a series of observations tiled on the sky. The total
exposure time is 5 ks, distributed over 4 tiles. The data were collected
between T0+38.2 ks and T0+45.8 ks, and are entirely in Photon Counting
(PC) mode.
An uncatalogued X-ray source is detected within the Fermi/LAT error circle.
The position of this source is RA, Dec=269.2518, +30.37356 which is
equivalent to:
RA (J2000): 17:57:00.43
Dec(J2000): +30:22:24.8
with an uncertainty of 2.7 arcsec (radius, 90% confidence). This
position is 12.2 arcmin from the Fermi/LAT position. The source has a
0.3-10 keV count rate of about 0.03 ct/sec. We cannot determine fading
at this time.
[GCN OPS NOTE(17oct16): Per author's request, the GRB name in the first sentence
was corrected from 16A to 15A.]
GCN Circular 20060
Subject
GRB161015A: AstroSat CZTI detection
Date
2016-10-17T07:03:29Z (9 years ago)
From
Varun Bhalerao at IUCAA <varunb@iucaa.in>
V. Kumar, V. Sharma, D. Bhattacharya and V. Bhalerao (IUCAA), A. R. Rao (TIFR) and S. Vadawale (PRL) report on behalf of the AstroSat CZTI collaboration:
Analysis of AstroSat CZTI data showed clear detection of a bright GRB161015A (Fermi LAT detection: Masanori Ohno et al., GCN Circ. 20054) in the 40-200 keV energy range. The light curve shows a complex structure with peak at 17:03:08.04 UT after 1 second of the Fermi Trigger at 17:03:07.04 UT. The measured peak count rate is 660.0 counts/sec above the background in combined data of four quadrants, with a total of 2942.0 counts. The local mean background count rate was 320.0 counts/sec. Using cumulative rates, we measure a T90 of 22.0 secs.
CZTI GRB detections are reported regularly on the payload site at http://astrosat.iucaa.in/czti/?q=grb. CZTI is built by a TIFR-led consortium of institutes across India, including VSSC, ISAC, IUCAA, SAC and PRL. The Indian Space Research Organisation funded, managed and facilitated the project.
GCN Circular 20062
Subject
Konus-Wind observation of GRB 161015A
Date
2016-10-17T13:30:12Z (9 years ago)
From
Dmitry Svinkin at Ioffe Institute <svinkin@mail.ioffe.ru>
D. Svinkin, S. Golenetskii, R. Aptekar, D. Frederiks, P. Oleynik,
M. Ulanov, A. Tsvetkova, A. Lysenko, A. Kozlova, and T. Cline
on behalf of the Konus-Wind team, report:
The long-duration GRB 161015A
(Fermi-LAT detection: Masanori Ohno et al., GCN Circ. 20054;
Fermi-GBM detection: Stanbro and Meegan, GCN Circ. 20056;
AstroSat-CZTI detection: Kumar et al., GCN Circ. 20060)
triggered Konus-Wind at T0=61386.899 s UT (17:03:06.899).
The burst light curve shows multipeaked structure
starting at ~T0-0.5 s and having a total duration of ~16 s.
The emission is seen up to 3 MeV.
The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB161015_T61386/
As observed by Konus-Wind, the burst
had a fluence of 1.11(-0.08,+0.09)x10^-5 erg/cm2,
and a 64-ms peak flux, measured from T0+1.888 s,
of 4.01(-0.84,+0.85)x10^-6 erg/cm2/s
(both in the 20 keV - 10 MeV energy range).
The time-averaged spectrum of the burst
(measured from T0 to T0+16.640 s)
is best fit in the 20 keV - 4 MeV range
by a power law with exponential cutoff model:
dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep)
with alpha = -1.12(-0.12,+0.13)
and Ep = 215(-26,+34) keV (chi2 = 60/73 dof).
Fitting by a GRB (Band) model yields the same alpha and Ep,
and an upper limit on the high energy photon index: beta < -2.6
(chi2 = 60/72 dof)
The spectrum near the maximum count rate
(measured from T0+0.256 to T0+8.448 s)
is best fit in the 20 keV - 4 MeV range
by a power law with exponential cutoff model:
with alpha = -0.68(-0.14,+0.16)
and Ep = 256(-26,+32) keV (chi2 = 73/73 dof).
Fitting by a GRB (Band) model yields the same alpha and Ep,
and an upper limit on the high energy photon index: beta < -3.2
(chi2 = 73/72 dof)
All the quoted errors are at the 90% confidence level.
All the quoted values are preliminary.
GCN Circular 20065
Subject
GRB 161015A: Swift/UVOT observations
Date
2016-10-17T19:48:19Z (9 years ago)
From
Massimiliano de Pasquale at IASF-Palermo <m.depasquale@ucl.ac.uk>
M. De Pasquale (MSSL-UCL) and J. Cannizzo (NASA/UMBC) report on
behalf of the Swift/UVOT team:
The Swift/UVOT report started to observe the field of the putative X-ray
afterglow of GRB 161015A, the Fermi/LAT burst (Ohno et al. GCN
Circ. 20054, D'Avanzo et al. GCN Circ. 20057), 38 ks after the
LAT trigger.
No optical counterpart to this source is found. The 3 sigma upper limit
is given in the table below.
T_start (s) T_end (s) Exposure Time (s) filter 3s UL
37991 45608 1210 u >20.35
The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.04 in the direction of the burst
(Schlegel et al. 1998).
--
Dr. Massimiliano De Pasquale
Research associate - Swift UVOT scientist
Mullard Space Science Laboratory, University College London
GCN Circular 20085
Subject
GRB 161015A: further Swift-XRT follow-up observations
Date
2016-10-20T14:41:03Z (9 years ago)
From
Andrea Melandri at INAF-OAB <andrea.melandri@brera.inaf.it>
A. Melandri, P. D'Avanzo (INAF-OAB), B. Sbarufatti (INAF-OAB/PSU) and J. Cannizzo (NASA/UMBC) report on behalf of the Swift team:
Swift-XRT carried out further observations of the field of the Fermi GRB 161015A (Ohno et al., GCN Circ. 20054; Stanbro & Meegan, GCN 20056) between T0+371.3 ks and T0+395.9 ks. The total exposure time is 5.0 ks, entirely in Photon Counting (PC) mode.
The source reported in D'Avanzo et al. (GCN Circ. 20057) as an X-ray afterglow candidate is no longer detected. The 3sigma u.l. is about 3.4e-3 ct/sec (corresponding to a 0.3-10 keV observed flux of 1.7e-13 erg cm^-2 s^-1, assuming a typical GRB spectrum). We thus confirm it as the X-ray afterglow associated with GRB 161015A.
This is an official product of the Swift-XRT team.
GCN Circular 20116
Subject
GRB 161015A: 15 GHz upper limits from AMI
Date
2016-10-27T21:38:30Z (9 years ago)
From
Kunal Mooley at Oxford U <kunal.mooley@physics.ox.ac.uk>
K. P. Mooley (Hintze Fellow, Oxford), 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 Fermi/LAT GRB 161015A (Ohno et al., GCN 20054) with the
AMI Large Array at 15 GHz on 2016 Oct 17.75, Oct 18.73, Oct 20.70, and
Oct 24.65 (UT) as part of the 4pisky program. We do not detect any radio
source at the XRT location (D'Avanzo et al., GCN 20057), with 3sigma
upper limits of 105 uJy, 96 uJy, 147 uJy, and 78 uJy respectively.
We thank the AMI staff for scheduling these observations. 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/.