GRB 160117A
GCN Circular 18910
Subject
GRB 160117A: Swift-XRT afterglow detection
Date
2016-01-21T07:19:22Z (10 years ago)
From
Kim Page at U.of Leicester <klp5@leicester.ac.uk>
A. Maselli (INAF-IASFPA), A. Melandri (INAF-OAB), P. D'Avanzo
(INAF-OAB), B. Sbarufatti (INAF-OAB/PSU), D.N. Burrows (PSU), T.G.R.
Roegiers (PSU), S.L. Gibson (U. Leicester), J.P. Osborne (U.
Leicester), K.L. Page (U. Leicester) and D. M. Palmer report on behalf
of the Swift-XRT team:
Swift-XRT has conducted further observations of the field of the
Swift/BAT-detected burst GRB 160117A (Palmer et al. GCN Circ. 18882).
The observations now extend from T0+68.7 ks to T0+304.5 ks. The source
previously reported by Maselli et al. (GCN Circ. 18888), "Source 1", is
fading with 3-sigma significance, and is therefore likely the GRB
afterglow. The position of this source is RA, Dec=20.3683, -0.6541
which is equivalent to:
RA (J2000): 01:21:28.39
Dec(J2000): -00:39:14.7
with an uncertainty of 3.8 arcsec (radius, 90% confidence). This
position is 65 arcsec from the Swift/BAT position.
The light curve can be modelled with a power-law decay with a decay
index of alpha=1.1 (+0.5, -0.4).
A spectrum formed from the PC mode data can be fitted with an absorbed
power-law with a photon spectral index of 3.7 (+0.9, -0.6). The
best-fitting absorption column is 1.2 (+0.6, -0.4) x 10^22 cm^-2, in
excess of the Galactic value of 4.4 x 10^20 cm^-2 (Willingale et al.
2013). The counts to observed (unabsorbed) 0.3-10 keV flux conversion
factor deduced from this spectrum is 2.6 x 10^-11 (3.7 x 10^-10) erg
cm^-2 count^-1.
A summary of the PC-mode spectrum is thus:
Total column: 1.2 (+0.6, -0.4) x 10^22 cm^-2
Galactic foreground: 4.4 x 10^20 cm^-2
Excess significance: 5.2 sigma
Photon index: 3.7 (+0.9, -0.6)
The results of the XRT-team automatic analysis of the likely afterglow
are at http://www.swift.ac.uk/ToO_GRBs/00670793/index_1.php.
The results of the full analysis of the XRT observations are available
at http://www.swift.ac.uk/ToO_GRBs/00670793.
This circular is an official product of the Swift-XRT team.
GCN Circular 18892
Subject
GRB 160117A: Swift/UVOT Upper Limits
Date
2016-01-19T02:00:12Z (10 years ago)
From
Lea Hagen at PSU <lea.zernow.hagen@gmail.com>
L. M. Z. Hagen (PSU) and C. B. Markwardt (NASA/GSFC)
report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 160117A
68.7 ks after the BAT trigger (Markwardt et al. GCN Circ. 18874). No
optical afterglow consistent with the XRT position of Source 1 (Maselli
et al. GCN Circ. 18888) is detected in the initial UVOT exposures.
Preliminary 3-sigma upper limits using the UVOT photometric system
(Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the first exposures
are:
Filter T_start(s) T_stop(s) Exp(s) Mag
v 75251 76158 885 >19.75
u 70499 70799 295 >19.80
w1 69593 80420 1226 >20.52
m2 68687 76854 1565 >20.90
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).
GCN Circular 18888
Subject
GRB 160117A: Swift-XRT observations
Date
2016-01-18T10:56:39Z (10 years ago)
From
Kim Page at U.of Leicester <klp5@leicester.ac.uk>
A. Maselli (INAF-IASFPA), A. Melandri (INAF-OAB), P. D'Avanzo
(INAF-OAB), B. Sbarufatti (INAF-OAB/PSU), D.N. Burrows (PSU), T.G.R.
Roegiers (PSU), S.L. Gibson (U. Leicester), J.P. Osborne (U.
Leicester), K.L. Page (U. Leicester) and D. M. Palmer report on behalf
of the Swift-XRT team:
We have analysed 4.6 ks of Photon Counting (PC) mode XRT data for the
Swift/BAT-detected burst GRB 160117A (Palmer et al. GCN Circ. 18882),
collected between T0+68.7 ks and T0+76.8 ks.
One uncatalogued X-ray source has been detected inside or close to the
Swift/BAT error region, it is below the RASS limit and shows no
definitive signs of fading. Therefore, at the present time we cannot
confirm this as the afterglow. Details of this source are given below:
Source 1:
RA (J2000.0): 20.3683 = 01:21:28.40
Dec (J2000.0): -0.6542 = -00:39:15.3
Error: 3.9 arcsec (radius, 90% conf.)
Count-rate: 0.0142 +/- 0.0020 ct s^-1
Flux: (4.04 +/- 0.58)e-13 erg cm^-2 s^-1 (observed, 0.3-10 keV)
The results of the XRT-team automatic analysis of the XRT observations,
including a position-specific upper limit calculator, are available at
http://www.swift.ac.uk/ToO_GRBs/00670793.
This circular is an official product of the Swift-XRT team.
GCN Circular 18882
Subject
GRB 160117A: Swift-BAT refined analysis
Date
2016-01-17T23:00:29Z (10 years ago)
From
Craig Markwardt at NASA/GSFC <craigm@milkyway.gsfc.nasa.gov>
D. M. Palmer, S. D. Barthelmy (GSFC), J. R. Cummings (GSFC/UMBC),
N. Gehrels (GSFC), H. A. Krimm (GSFC/USRA), A. Y. Lien (GSFC/UMBC),
C. B. Markwardt (GSFC), D. M. Palmer (LANL), T. Sakamoto (AGU),
M. Stamatikos (OSU), T. N. Ukwatta (LANL)
(i.e. the Swift-BAT team):
Using the data set from T-173 to T+1029 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 160117A (trigger #670793)
(Markwardt, et al., GCN Circ. 18874). The BAT ground-calculated position is
RA, Dec = 20.367, -0.677 deg which is
RA(J2000) = 01h 21m 28.0s
Dec(J2000) = -00d 40' 37.8"
with an uncertainty of 1.8 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 60%.
The mask-weighted light curve consists of a faint precursor from about
T-70 sec to T+30 sec, followed by brighter double-peaked structure from
about T+30 sec to T+115 sec. T90 (15-350 keV) is 118.58 +- 20.46 sec
(estimated error including systematics).
The time-averaged spectrum from T-46 to T+109 sec is best fit by a simple
power-law model. The power law index of the time-averaged spectrum is
2.14 +- 0.11. The fluence in the 15-150 keV band is 3.1 +- 0.2 x 10^-6 erg/cm2.
The 1-sec peak photon flux measured from T+76 sec in the 15-150 keV band
is 1.4 +- 0.2 ph/cm2/sec. All the quoted errors are at the 90% confidence
level.
Please note that GRB 160117B was incorrectly marked with the same trigger
number as GRB 160117A in Sonbas et al. 2016 (GCN Circ. 18875). The correct
trigger number for 160117A is above.
The results of the batgrbproduct analysis are available at
http://gcn.gsfc.nasa.gov/notices_s/670793/BA/
GCN Circular 18874
Subject
GRB 160117A: Swift detection of a burst
Date
2016-01-17T10:25:30Z (10 years ago)
From
David Palmer at LANL <palmer@lanl.gov>
C. B. Markwardt (NASA/GSFC), K. L. Page (U Leicester) and
D. M. Palmer (LANL) report on behalf of the Swift Team:
At 10:13:39 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 160117A (trigger=670793). Swift could not slew to the
burst location due to an observing constraint.
The BAT on-board calculated location is
RA, Dec 20.408, -0.627 which is
RA(J2000) = 01h 21m 38s
Dec(J2000) = -00d 37' 37"
with an uncertainty of 3 arcmin (radius, 90% containment, including
systematic uncertainty). The BAT light curve showed a complex
structure with a duration of about 30 sec. The peak count rate
was ~1300 counts/sec (15-350 keV), at ~6 sec after the trigger.
Due to a Moon observing constraint, Swift cannot slew to the BAT
position until 00:56 UT on 2016 January 18. There will thus be no XRT
or UVOT data for this trigger before this time.
Burst Advocate for this burst is C. B. Markwardt (Craig.Markwardt AT nasa.gov).
Please contact the BA by email if you require additional information
regarding Swift followup of this burst. In extremely urgent cases, after
trying the Burst Advocate, you can contact the Swift PI by phone (see
Swift TOO web site for information: http://www.swift.psu.edu/too.html.)