GRB 161224A
GCN Circular 20337
Subject
GRB 161224A: Swift-BAT refined analysis
Date
2016-12-25T18:23:24Z (8 years ago)
From
Amy Lien at GSFC <amy.y.lien@nasa.gov>
T. N. Ukwatta (LANL), S. D. Barthelmy (GSFC),
A. Cholden-Brown (PSU), 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),
M. Stamatikos (OSU), T. N. Ukwatta (LANL)
(i.e. the Swift-BAT team):
Using the data set from T-239 to T+963 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 161224A (trigger #728268)
(Cholden-Brown et al., GCN Circ. 20335). The BAT ground-calculated position is
RA, Dec = 204.820, -18.028 deg which is
RA(J2000) = 13h 39m 16.9s
Dec(J2000) = -18d 01' 41.7"
with an uncertainty of 1.9 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 48%.
The mask-weighted light curve shows a single pulse structure that starts at
~ T+12 s, peaks at ~T+33 s, and ends at ~T+65 s. T90 (15-350 keV) is
47.04 +- 12.12 sec (estimated error including systematics).
The time-averaged spectrum from T+12.46 to T+65.18 sec is best fit by a power law
with an exponential cutoff. This fit gives a photon index -0.21 +- 1.56,
and Epeak of 34.5 +- 5.6 keV (chi squared 44.84 for 56 d.o.f.). For this
model the total fluence in the 15-150 keV band is (8.2 +- 1.3) x 10^-7 erg/cm2
and the 1-sec peak flux measured from T+32.88 sec in the 15-150 keV band is
0.8 +- 0.3 ph/cm2/sec. A fit to a simple power law gives a photon index
of 2.21 +- 0.21 (chi squared 57.66 for 57 d.o.f.). 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/728268/BA/
GCN Circular 20338
Subject
GRB 161224A: Swift-XRT refined Analysis
Date
2016-12-26T06:15:37Z (8 years ago)
From
Aaron Cholden-Brown at PSU/Swift <aaronb@swift.psu.edu>
A. Cholden-Brown (PSU) and P.A. Evans (U. Leicester) report on behalf
of the Swift-XRT team:
We have analysed 4.9 ks of XRT data for GRB 161224A, from 28.3 ks to
52.2 ks after the BAT trigger. The data are entirely in Photon
Counting (PC) mode. A fading X-ray source is found in the BAT error
region. Using 617 s of PC mode data and 1 UVOT image, we find an
enhanced XRT position (using the XRT-UVOT alignment and matching UVOT
field sources to the USNO-B1 catalogue): RA, Dec = 204.81579, -18.02909
which is equivalent to:
RA (J2000): 13h 39m 15.79s
Dec(J2000): -18d 01' 44.7"
with an uncertainty of 4.1 arcsec (radius, 90% confidence).
The light curve can be modelled with a power-law decay with a decay
index of alpha=2.8 (+0.8, -2.1).
If the light curve continues to decay with a power-law decay index of
2.8, the count rate at T+24 hours will be 8.4 x 10^-4 count s^-1
The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/00728268.
This circular is an official product of the Swift-XRT team.
GCN Circular 20339
Subject
GRB 161224A: Swift/UVOT Upper limits
Date
2016-12-26T12:12:17Z (8 years ago)
From
Paul Kuin at MSSL <npkuin@gmail.com>
N. P. M. Kuin (UCL-MSSL) and A. Cholden-Brown (PSU)
report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 161224A
28.3ks after the BAT trigger after a Sun constraint (Cholden-Brown
et al., GCN Circ. 20335). At the position of the XRT source (Cholden-Brown
and
Evans, GCN Circ. 20338) no uv-optical source was found to the upper limits
below.
Preliminary 3-sigma upper limits using the UVOT photometric system
(Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the early exposures
are:
Filter T_start(s) T_stop(s) Exp(s) Mag
u 44266.0 44786.3 508 >19.99
v 28322.2 50899.7 1770 >19.90
uvw1 35223.6 41032.4 786 >19.91
uvw2 46285.0 46772.6 480 >19.88
uvm2 29234.3 35216.6 1198 >20.48
The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.096 in the direction of the burst
(Schlegel et al. 1998).
GCN Circular 20340
Subject
GRB 161224A: TSHAO optical observations
Date
2016-12-26T13:04:31Z (8 years ago)
From
Alexei Pozanenko at IKI, Moscow <apozanen@iki.rssi.ru>
E. Mazaeva (IKI), I. Reva (Fesenkov Astrophysical Institute), A.
Kusakin (Fesenkov Astrophysical Institute), A. Volnova (IKI), A.
Pozanenko (IKI) report on behalf of larger GRB follow-up collaboration:
We observed the field of GRB 161224A (Swift trigger=728268,
Cholden-Brownet al., GCN 20333) with Zeiss-1000 (East) 1-m telescope of
Tien Shan Astronomical Observatory. We obtained several images in R
filter starting on Dec. 25 (UT) 00:13:31 and Dec. 25 (UT) 23:45:12. We
do not detect any evident variable source in the BAT ground-calculated
position (Ukwatta al., GCN 20337). Within enhanced XRT position
(Cholden-Brownet al., GCN 20338) we not detected any source. Preliminary
photometry of the field is following
Date UT start t-T0 Filter Exp. OT Err. UL
(mid, days) (s)
2016-12-25 00:13:31 0.10201 R 16*180 n/d n/d 21.1
2016-12-25 23:45:12 1.07646 R 11*180 n/d n/d 20.7
Photometry is based on nearby USNO-B1.0 stars
0719-0341418 17.14
0720-0349085 17.50
0720-0348989 16.94
0719-0341338 15.94
A finding chart can be found in
http://grb.rssi.ru/GRB161224A/GRB161224A_20161225_TSHAO_fc.png