- GCN Circular #21142
S. D. Barthelmy (GSFC), A. Y. Lien (GSFC/UMBC), D. M. Palmer (LANL),
and T. Sakamoto (AGU), report on behalf of the Swift Team:
At 10:40:40 UT on 2017-05-24, the Swift Burst Alert Telescope (BAT) triggered on
GRB 170524B (trigger=754265). However, on-board analysis was truncated by
a pre-planned slew to a scheduled target. Subsequent ground analysis
using data from T+2 to T+101 s finds the source at a location of
RA, Dec 90.864, -17.086, which is
RA(J2000) = 06h 03m 27s
Dec(J2000) = -17d 05' 11"
with an uncertainty of 3 arcmin (radius, 90% containment, including
systematic uncertainty).
The BAT light curve shows a complex structure about 50 seconds long.
The raw peak count rate was ~18000 counts/sec (15-350 keV), at ~7 sec after
the trigger. T90 (15-350 keV) estimated using the raw light curve is 46.4 +- 1.6 sec
(estimated error including systematics).
The time-averaged spectrum from T+1.8 to T+49.6 sec is best fit by a simple
power-law model. The power law index of the time-averaged spectrum is
1.15 +- 0.06. The fluence in the 15-150 keV band is (6.6 +/- 0.2) x 10^-6 erg/cm2.
The 1-sec peak photon flux measured from T+6.70 sec in the 15-150 keV band
is 0.3 ph/cm2/sec. All the quoted errors are at the 90% confidence
level.
This event was also detected by CALET, KONUS-Wind, and INTEGRAL SPI ACS.
A Swift Target of Opportunity observation has been requested.
The results of the batgrbproduct analysis are available at
http://gcn.gsfc.nasa.gov/notices_s/00753445006/BA/
- GCN Circular #21144
P. A. Evans (U. Leicester) reports on behalf of the Swift team:
Swift has initiated a ToO observation of the Swift/BAT GRB 170524B.
Automated analysis of the XRT data will be presented online at
http://www.swift.ac.uk/ToO_GRBs/00020775
Any uncatalogued X-ray sources detected in this analysis will be
reported on this website and via GCN COUNTERPART notices. These are
not necessarily related to the Swift/BAT event. 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 #21147
R.Podesta, C.Lopez, F. Podesta Observatorio Astronomico Felix Aguilar (OAFA),
National University of San Juan, Argentina
H. Levato, C. Saffe
Instituto de Ciencias Astronomicas,de la Tierra y del Espacio (ICATE),
San Juan, Argentina
V. Lipunov, E. Gorbovskoy, V.Kornilov, N.Tyurina, D.Kuvshinov, A.V.Krylov,
I.Gorbunov, P.Balanutsa, A.Kuznetsov, V.V.Chazov, D. Vlasenko
Lomonosov Moscow State University, Sternberg Astronomical Institut of MSU
K.Ivanov, S.Yazev, N.M.Budnev, O.Gres, O.Chuvalaev, V.A.Poleshchuk, O. Ershova
Irkutsk State University
V.Yurkov, Yu.Sergienko
Blagoveschensk Educational State University, Blagoveschensk
A. Tlatov, V.Senik, A.V. Parhomenko, D. Dormidontov
Kislovodsk Solar Station of the Pulkovo Observatory
D.Buckley, S. Potter, A.Kniazev, M.Kotze
South African Astronomical Observatory
R. Rebolo, M. Serra, N. Lodieu, G. Israelian, L. Suarez-Andres
The Instituto de Astrofisica de Canarias
MASTER robotic telescope (6 square degrees)
located in OAFA was pointed to the GRB170525B (Barthelmy et al., GCN
#21142) 15191 sec after notice
time and 43294 sec after trigger time at 2017-05-25 22:42:14 UT. On our
first (180s exposure) set we haven`t found optical transient within
Master error-box (ra=90.8625 dec=-17.0861 r=0.1).
The 5-sigma upper limit has been about 18.3 mag
There is no OT at added images brighter 19.9 at Swift XRT position
(Barthelmy et al., GCN #21142; Evans, GCN #21144 ).
The observations made on zenit distance = 59 degrees, galaxy latitude b =
-18 degree.
The moon ( 0 % bright part) below the horizon (The altitude of the Moon is
-8 degree ).
Observations started at twilight. The sun altitude is -12.7 degree.
The object can be observed till 2017-05-26 01:12:20
The message may be cited.
- GCN Circular #21148
D. Frederiks, S. Golenetskii, R.Aptekar, P. Oleynik, M. Ulanov,
D. Svinkin, A. Tsvetkova, A.Lysenko, A. Kozlova, and T. Cline,
on behalf of the Konus-Wind team, report:
The long GRB 170524B (Swift/BAT detection: Barthelmy et al., GCN 21142)
triggered Konus-Wind at T0=3D38438.475 s UT (10:40:38.475).
The KW light curve shows a multi-peaked emission with a total duration
of ~24 s.
The emission is seen up to ~10 MeV.
As observed by Konus-Wind, the burst had a fluence of
(5.7 =B1 0.4)x10^-5 erg/cm2 and a 64-ms peak energy flux,
measured from T0+1.644, of (1.44 =B1 0.10)x10^-5 erg/cm2
(both in the 20 keV - 10 MeV energy range).
The time-integrated spectrum (measured from T0 to T0+21.760 s)
is best fit in the 20 keV - 15 MeV range by a cutoff power-law
(CPL) function with the following model parameters:
the photon index alpha =3D -0.85(-0.06,+0.06),
and the peak energy Ep =3D 766(-74,+87) keV,
chi2 =3D 93/98 dof.
Fitting this spectrum with the GRB (Band) function yields
the same alpha and Ep, and an upper limit on beta of -2.5,
chi2 =3D 93/97 dof.
The spectrum near the peak count rate (measured from T0 to T0+5.376 s)
is best fit in the 20 keV - 15 MeV range by the CPL function
with the following model parameters:
the photon index alpha =3D -0.72(-0.06,+0.06),
and the peak energy Ep =3D 860(-73,+83) keV,
chi2 =3D 111/98 dof.
Fitting this spectrum with the GRB (Band) function yields
the same alpha and Ep, and an upper limit on beta of -2.7,
chi2 =3D 110/97 dof.
The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB170524_T38438/
All the quoted errors are estimated at the 90% confidence level.
All the presented results are preliminary.
- GCN Circular #21150
A. Cholden-Brown (PSU), V. D'Elia (ASDC), A. D'Ai (INAF-IASFPA), A.
Melandri (INAF-OAB), D.N. Burrows (PSU), S. J. LaPorte (PSU), S.L.
Gibson (U. Leicester), J.P. Osborne (U. Leicester) and P.A. Evans (U.
Leicester) report on behalf of the Swift-XRT team:
Swift-XRT has performed follow-up observations of the
Swift/BAT-detected burst GRB 170524B (Barthelmy et al. GCN Circ.
21142), collecting 2.1 ks of Photon Counting (PC) mode data between
T0+119.5 ks and T0+126.8 ks.
One uncatalogued X-ray source has been detected consistent with being
within 296 arcsec of the Swift/BAT position, 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): 90.86806 = 06:03:28.33
Dec (J2000.0): -17.08282 = -17:04:58.2
Error: 2.3 arcsec (radius, 90% conf. [Enhanced position])
Count-rate: 0.0240 +/- 0.0038 ct s^-1
Distance: 18 arcsec from Swift/BAT position.
Flux: (7.1 +/- 1.1)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/00020775.
This circular is an official product of the Swift-XRT team.
- GCN Circular #21168
J.D. Gropp (PSU), M.H. Siegel (PSU), J.A. Kennea (PSU), A.
Cholden-Brown (PSU) reporting on behalf of the Swift team.
The Swift-UVOT and XRT began settled observations of the field of GRB
170524B 120 ks after the
BAT trigger (Barthelmy et al., GCN Circ. 21142). A fading source
consistent with the XRT position
is detected in the UVOT exposures.
Swift-XRT performed follow-up observations of the
Swift/BAT-detected burst GRB 170524B (Barthelmy et al. GCN Circ.21142),
collecting an additional 3ks (5.1 total) of Photon Counting (PC) mode data.
One uncatalogued X-ray source has been detected consistent with being
within 296 arcsec of the Swift/BAT position. There is also evidence of fading,
which is confirmed with UVOT analysis.
XRT light curve can be modeled with a power-law decay with a decay
index alpha = 1.3
The preliminary UVOT position is:
RA (J2000) = 06:03:28.49 = 90.86872 (deg.)
Dec (J2000) = -17:04:58.7 = -17.08297 (deg.)
with an estimated uncertainty of 0.4 arc sec. (radius, 90% confidence).
Preliminary detections 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
white 120431 126833 1297 19.89+-0.08
white 274703 286595 2027 21.11+-0.23
The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.19 in the direction of the burst.
The decay inferred from the UVOT white data suggests a slope of
approximately -1.3.
This circular is an official product of the Swift team.
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