GRB 110715A
GCN Circular 12185
Subject
GRB110715A: spectral lag analysis
Date
2011-07-20T13:34:29Z (15 years ago)
From
Dong Xu at Weizmann Inst <dong.xu@weizmann.ac.il>
D. Xu (WIS) reports:
GRB 110715A was detected by Swift/BAT (Sonbas et al., GCN 12158;
Ukwatta et al., GCN 12160), Konus-Wind (Golenetskii et al., GCN
12166), and Suzaku/WAM (Ohmori et al., GCN 12184). The prompt emission
of this burst has a high photon count rate. And the lightcurve shows a
multi-peaked structure lasting ~5s (i.e., T0+5s, where T0 is the
trigger time), followed by a much weaker emission up to ~T0+20s.
Therefore, the overall T90 duration is ~10s or even a bit longer. On
the other hand, such a lightcurve feature is reminiscent of previous
short bursts with extended tail emissions.
With the redshift z = 0.82 (Piranomonte et al., GCN 12164) and the
cosmological parameters H_0 = 71 km/s/Mpc, Omega_M = 0.27,
Omega_Lambda = 0.73, the isotropic energy release E_iso is (4.1 �
0.4)x10^52 erg, the isotropic peak luminosity L_iso,p is (3.9 �
0.2)x10^52 erg/s, and the rest-frame \nu_F\nu peak energy Ep_rest is
220 � 20 keV (Golenetskii et al., GCN 12166). Thus, the values of Eiso
and Ep_rest are well consistent with the Eiso-Ep_rest relation (i.e.,
Amati relation) for long GRBs (or collapsar bursts).
The Swift/BAT data were reduced in a standard way and a CCF method was
used to derive spectral lags upon the lightcurves with 0.064s binning
(Xu et al., ApJ, 696, 971). We found lags of 0.04+/-0.01s (1sigma) for
15-25 V.S. 25-50 keV and 0.04+/-0.01 (1sigma) for 50-75 V.S. 75-350
keV. Thus, this event also fits the Liso-spectral lag relation for
long GRBs.
At z=0.82, searching for an accompanying SN is doable but requires
very deep photometric follow-ups (ref. Tanvir et al., ApJ, 725, 625).
GCN Circular 12184
Subject
GRB 110715A : Suzaku WAM observation of the prompt emission
Date
2011-07-20T02:05:47Z (15 years ago)
From
Norisuke Ohmori at Miyazaki U <ohmori@astro.miyazaki-u.ac.jp>
N. Ohmori, M. Akiyama, M. Yamauchi (Univ. of Miyazaki),
K. Yamaoka (Aoyama Gakuin U.), M. Ohno, Y. Hanabata, T. Uehara,
T. Takahashi, M. Mizuno, Y. Fukazawa (Hiroshima U.), S. Sugita (Nagoya U.),
T. Yasuda, Y. Terada, W. Iwakiri, K. Takahara, M. Asahina, S. Kobayashi,
M. Tashiro (Saitama U.), M. Kokubun, T. Takahashi (ISAS/JAXA),
Y. E. Nakagawa (Waseda U.), Y. Urata, P. Tsai, C-J. Chuang (NCU),
K. Nakazawa, K. Makishima (Univ. of Tokyo), on behalf of the Suzaku WAM team, report:
The long GRB 110715A (Swift/BAT trigger #457330 ; Sonbas et al., GCN 12158)
triggered the Suzaku Wide-band All-sky Monitor (WAM)
which covers an energy range of 50 keV - 5 MeV at 13:13:49.914 UT (=T0).
The observed light curve shows a multi-peaked structure starting at T0,
ending at T0+4s, followed by a weaker emission seen up to T0+20s
with a duration (T90) of 8 seconds.
The fluence in 100 - 1000 keV was 1.28 (-0.06, +0.07) x10^-5 erg/cm^2.
The 1-s peak flux measured from T0+3s was 20.3 (-1.1, +1.0) photons/cm^2/s
in the same energy range.
Preliminary result shows that the time-averaged spectrum from T0-3s to
T0+20s is well fitted by a single power-law with a photon index
of 2.67 (-0.18, +0.19) (chi^2/d.o.f = 24.0/15).
All the quoted errors are at statistical 90% confidence level.
The light curves for this burst will be available at:
http://www.astro.isas.jaxa.jp/suzaku/HXD-WAM/WAM-GRB/grb/trig/grb_table.html
GCN Circular 12174
Subject
GRB 110715A optical observations
Date
2011-07-19T12:16:46Z (15 years ago)
From
AAVSO GRB Network at AAVSO <matthewt@aavso.org>
Peter Nelson (Ellinbank, Victoria, Australia) reported to the AAVSO
International High Energy Network the following optical observations of
GRB 110715A (Sonbas et al., GCN #12158):
P. Nelson (Ellinbank Observatory, Ellinbank, VIC, Australia) reports a
detection of GRB 110715A from fifteen frames of 30-seconds exposure each
taken with a clear filter through a 0.32-cm PlaneWave f/8 CDK and SBIG
ST8XE camera. The magnitude derived from all frames is m(CR) = 18.0 +/-
0.2 at the mid-point exposure time of 2011 July 15 14:05:01 UT.
Magnitudes were measured relative to the USNO-B1.0 comparison star at RA:
15:50:41.62, Decl: -46:14:25.91 with magnitude R=15.21 (see Piranomonte et
al., GCN #12164).
Nelson reports that time-series was obtained by averaging the 15 frames
into three consecutive groups of five frames, yielding the following
magnitudes:
Time (UT) Mag (Clear, R zeropoint)
13:54:23 18.01 +/- 0.18
14:05:28 17.93 +/- 0.15
14:15:12 18.47 +/- 0.25
The position derived from these images is RA: 15:50:44.07, Decl:
-46:14:06.5, which is fully consistent with the optical position given by
Kuin et al. (GCN #12162).
The AAVSO International High Energy Network was made possible through
grants from the Charles Curry Foundation and from NASA.
GCN Circular 12171
Subject
GRB 110715A: ATCA detection of the radio counterpart
Date
2011-07-19T00:27:05Z (15 years ago)
From
Tara Murphy at U.Sydney <tara@physics.usyd.edu.au>
Paul J. Hancock, Tara Murphy (U of Sydney) and Brian P. Schmidt (ANU)
We observed GRB 110715A (GCN 12158) with the Australian Telescope
Compact Array (ATCA) on July 18 at 12.2 UT (~3 days after the GRB trigger).
We find a single unresolved radio source consistent with the UVOT
position (GCN 12162). The source has a measured flux density of
2.4 +/- 0.1 mJy/beam at 44.00 GHz.
Further observations are planned. We thank the observatory staff for
scheduling and supporting these observations.
GCN Circular 12169
Subject
GRB110715A: GROND Detection of the Optical/NIR Afterglow
Date
2011-07-18T17:16:47Z (15 years ago)
From
Patricia Schady at MPE/Swift <pschady@mpe.mpg.de>
A. C. Updike (NASA/GSFC), P. Schady, J. Greiner (both MPE Garching),
T. Kruehler (DARK/NBI), D. A. Kann, S. Klose and A. Rossi (all TLS
Tautenburg) report on behalf of the GROND team:
We observed the field of GRB 110715A (Swift trigger 457330; Sonbas et
al., GCN #12158) simultaneously in g'r'i'z'JHK with GROND (Greiner et
al. 2008, PASP 120, 405) mounted at the 2.2 m MPI/ESO telescope at La
Silla Observatory (Chile).
Observations started at 00:35 UT on 18th July, lasting just under 2hrs
and with a midtime ~3dys after the GRB trigger. They were performed at
an average seeing of 1.1" and at an average airmass of 1.
We found a single point source within the 2.2" Swift-XRT error circle
reported by Evans et al. (GCN #12161), consistent with the UVOT
position (Kuin et al., GCN #12162).
Based on 4136s of total exposures in g'r'i'z' and 4320s in JHK, we
estimate preliminary magnitudes (all AB system) of
g' = 22.59 +/- 0.09
r' = 21.22 +/- 0.02
i' = 20.53 +/- 0.02
z' = 19.93 +/- 0.02
J = 19.56 +/- 0.24
H = 18.79 +/- 0.17
K = 18.86 +/- 0.31
Given optical and NIR magnitudes are calibrated against GROND
zeropoints and 2MASS field stars, respectively, and are not corrected
for the expected Galactic foreground extinction corresponding to a
reddening of E(B-V)=0.60 mag in the direction of the burst (Schlegel
et al. 1998).
GCN Circular 12168
Subject
GRB 110715A: APEX detection of the submm counterpart
Date
2011-07-17T02:08:00Z (15 years ago)
From
Antonio Deugarte at IAA-CSIC <deugarte@iaa.es>
A. de Ugarte Postigo (DARK/NBI), A. Lundgren, F. Mac-Auliffe,
F.M. Montenegro, D.A. Garc�a-Appadoo, I. de Gregorio-Monsalvo,
S. Martin, C. De Breuk (ESO), P. Bergman, M. Hajigholi (OSO),
C.C. Thoene, J. Gorosabel, A.J. Castro-Tirado (IAA-CSIC),
J.P.U. Fynbo (DARK/NBI) and S. Covino (INAF-OAB) report on
behalf of a larger collaboration:
We have observed the field of GRB 110715A (Sonbas et al. GCN 12158)
using LABOCA/APEX at Chajnantor (Chile) in the 870 micrometer band.
The weather conditions were good, with a precipitable water vapor
of 0.62mm. Observations began on July 16 at 23:21 UT (1.42 days after
the burst) and were performed using the photometric mode, centred at
the position of the optical counterpart (Kuin et al. GCN 12162,
Piranomonte et al. GCN 12164).
On a preliminary analysis of 88 minutes on source we detect a flux at
the position of the afterglow of 11.0+/-2.3 mJy.
Further observations are foreseen. We encourage follow-up in other
wavelengths.
GCN Circular 12166
Subject
Konus-Wind observation of GRB 110715A
Date
2011-07-16T10:11:53Z (15 years ago)
From
Dmitry Frederiks at Ioffe Institute <fred@mail.ioffe.ru>
S. Golenetskii, R.Aptekar, D. Frederiks, E. Mazets, V. Pal'shin,
P. Oleynik, M. Ulanov, D. Svinkin, and T. Cline on behalf
of the Konus-Wind team, report:
The bright GRB 110715A (Swift-BAT trigger #457330:
Sonbas et al., GCN 12158; Ukwatta et al., GCN 12160)
triggered Konus-Wind at T0=47635.304s UT (13:13:55.304)
The burst light curve shows a bright pulse, which peaked at T0+2s,
and a much weaker pulse at ~T0+11s.
A total burst duration is ~20 s.
The emission is seen up to ~10 MeV.
The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB110715_T47635/
As observed by Konus-Wind the burst
had a fluence of (2.3 � 0.2)x10-5 erg/cm2,
and a 64-ms peak flux, measured from T0+1.984 s,
of (1.1 � 0.1)x10-5 erg/cm2/s
(both in the 20 keV - 10 MeV energy range).
The time-integrated spectrum of the burst
(measured from T0 to T0+18.432 s) is best fitted
in the 20 keV - 10 MeV range by the GRB (Band)
model, for which:
the low-energy photon index alpha = -1.23 (-0.08, +0.09),
the high energy photon index beta = -2.7 (-0.5, +0.2),
the peak energy Ep = 120(-11, +12) keV,
chi2 = 85.8/84 dof.
The spectrum at the maximum count rate
(measured from T0+0.256 to T0+2.048 s) is best fitted
in the 20 keV - 10 MeV range by the GRB (Band)
model, for which:
the low-energy photon index alpha = -1.05 (-0.11, +0.11),
the high energy photon index beta = -3.6 (<-3.0),
the peak energy Ep = 148(-10, +11) keV,
chi2 = 51.5/55 dof.
Assuming the VLT redshift z = 0.82 (Piranomonte et al., GCN 12164)
and a standard cosmology model
with H_0 = 71 km/s/Mpc, Omega_M = 0.27, Omega_Lambda = 0.73,
the isotropic energy release E_iso is (4.1 � 0.4)x10^52 erg,
the peak luminosity L_iso_max is (3.9 � 0.2)x10^52 erg/s,
and Ep_rest is 220 � 20 keV.
All the quoted results are preliminary.
All the quoted errors are at the 90% confidence level
GCN Circular 12165
Subject
GRB 110715A: Swift-XRT refined Analysis
Date
2011-07-16T06:54:38Z (15 years ago)
From
Phil Evans at U of Leicester <pae9@star.le.ac.uk>
P.A. Evans (U. Leicester) and E. Sonbas (GSFC/USRA/Adiyaman Univ.)
report on behalf of the Swift-XRT team:
We have analysed 4.2 ks of XRT data for GRB 110715A (Sonbas et al. GCN
Circ. 12158), from 79 s to 29.4 ks after the BAT trigger. The data
comprise 400 s in Windowed Timing (WT) mode (the first 10 s were taken
while Swift was slewing) with the remainder in Photon Counting (PC)
mode. The enhanced XRT position for this burst was given by Evans et
al. (GCN. Circ 12161).
The light curve can be modelled with an initial power-law decay with an
index of alpha=0.57 (+/-0.05), followed by a break at T+2415 s to an
alpha of 1.78 (+/-0.13).
A spectrum formed from the WT mode data can be fitted with an absorbed
power-law with a photon spectral index of 1.91 (+/-0.07). The
best-fitting absorption column is 4.7 (+0.4, -0.3) x 10^21 cm^-2, in
excess of the Galactic value of 2.9 x 10^21 cm^-2 (Kalberla et al.
2005). The PC mode spectrum has a photon index of 1.85 (+/-0.13) and a
best-fitting absorption column of 6.0 (+/-0.8) x 10^21 cm^-2. The
counts to observed (unabsorbed) 0.3-10 keV flux conversion factor
deduced from this spectrum is 5.3 x 10^-11 (8.7 x 10^-11) erg cm^-2
count^-1.
A summary of the PC-mode spectrum is thus:
Total column: 6.0 (+/-0.8) x 10^21 cm^-2
Galactic foreground: 2.9 x 10^21 cm^-2
Excess significance: 12.6 sigma
Photon index: 1.85 (+/-0.13)
The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/00457330.
This circular is an official product of the Swift-XRT team.
GCN Circular 12164
Subject
GRB110715A: VLT redshift
Date
2011-07-16T05:19:25Z (15 years ago)
From
Valerio D'Elia at ASDC <delia@asdc.asi.it>
S. Piranomonte (OAR/INAF), S. D. Vergani (OAB/INAF), D. Malesani, J. P. U.
Fynbo (DARK/NBI), K. Wiersema (Leicester), L. Kaper (Amsterdam) report on
behalf of the X-shooter GRB GTO collaboration:
We observed the optical afterglow of GRB 110715A (Sonbas et al., GCN Circ.
12158) with the ESO VLT equipped with the X-shooter spectrograph.
The optical afterglow is well detected in the R-band acquisition image
(taken on Jul 16.06 UT, i.e. 12.3 hr after the GRB), and has a magnitude
of R = 18.45 assuming R=15.21 for the USNO-B1 star at RA = 15:50:41.62,
Dec = -46:14:25.91.
Spectroscopic observations lasted for about 10 minutes, with a mean time
2011 Jul 16.08 UT (12.7 hr after the GRB). The seeing was about 0.9". We
then had to interrupt our observations due to strong wind.
We detect Ca II and Ca I absorption lines at a common redshift of z=0.82.
The wavelength calibration is based on archival calibration files.
We acknowledge excellent support from the night astronomer at the VLT,
Christophe Martayan, the telescope operator, Claudia Cid, and the shift
leader, Jonathan Smoker.
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GCN Circular 12162
Subject
GRB 110715A: Swift/UVOT Detection
Date
2011-07-15T22:32:12Z (15 years ago)
From
Paul Kuin at MSSL <npkuin@gmail.com>
N.P.M. Kuin (MSSL-UCL) and E. Sonbas (GSFC/USRA/Adiyaman Univ.)
report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 110715A
100 s after the BAT trigger (Sonbas et al., GCN Circ. 12158).
The preliminary UVOT position is:
RA (J2000) = 15:50:44.09 = 237.68369 (deg.)
Dec (J2000) = -46:14:06.53 = -46.23515 (deg.)
with an estimated uncertainty of 0.56 arc sec. (radius, 90% confidence).
Preliminary detections and 3-sigma upper limits using the UVOT
photometric system
(Poole et al. 2008, MNRAS, 383, 627) for the early exposures are:
Filter T_start(s) T_stop(s) Exp(s) Mag
white 100 249 147 17.37 +/- 0.06
u 312 501 187 17.86 +/- 0.09
b 3734 3857 121 19.5 +/- 0.3
white 3960 4160 197 19.92 +/- 0.16
uvw2 4166 4366 197 >20.1
v 4371 4571 197 19.3 +/- 0.3
uvm2 4576 6211 393 >20.3
uvw1 4781 6280 259 >20.1
u 4986 5186 197 20.1 +/- 0.4
b 5192 5391 197 19.9 +/- 0.2
The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.59 in the direction of the burst
(Schlegel et al. 1998).
GCN Circular 12161
Subject
GRB 110715A: Enhanced Swift-XRT position
Date
2011-07-15T18:40:34Z (15 years ago)
From
Phil Evans at U of Leicester <pae9@star.le.ac.uk>
P.A. Evans, M.R. Goad, J.P. Osborne and A.P. Beardmore (U. Leicester)
report on behalf of the Swift-XRT team.
Using 120 s of XRT Photon Counting mode data and 1 UVOT
images for GRB 110715A, we find an astrometrically corrected X-ray
position (using the XRT-UVOT alignment and matching UVOT field sources
to the USNO-B1 catalogue): RA, Dec = 237.68361, -46.23583 which is equivalent
to:
RA (J2000): 15h 50m 44.07s
Dec (J2000): -46d 14' 09.0"
with an uncertainty of 2.2 arcsec (radius, 90% confidence).
This position may be improved as more data are received. The latest
position can be viewed at http://www.swift.ac.uk/xrt_positions. Position
enhancement is described by Goad et al. (2007, A&A, 476, 1401) and Evans
et al. (2009, MNRAS, 397, 1177).
This circular was automatically generated, and is an official product of the
Swift-XRT team.
GCN Circular 12160
Subject
GRB 110715A: Swift-BAT refined analysis
Date
2011-07-15T18:25:58Z (15 years ago)
From
Scott Barthelmy at NASA/GSFC <scott@lheamail.gsfc.nasa.gov>
T. N. Ukwatta (MSU) S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC),
J. R. Cummings (GSFC/UMBC), N. Gehrels (GSFC), H. A. Krimm (GSFC/USRA),
C. B. Markwardt (GSFC), D. M. Palmer (LANL), T. Sakamoto (GSFC/UMBC),
E. Sonbas (GSFC/USRA/Adiyaman Univ.), M. Stamatikos (OSU), J. Tueller (GSFC),
(i.e. the Swift-BAT team):
Using the data set from T-60 to T+243 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 110715A (trigger #457330)
(Sonbas, et al., GCN Circ. 12158). The BAT ground-calculated position is
RA, Dec = 237.665, -46.237 deg, which is
RA(J2000) = 15h 50m 39.7s
Dec(J2000) = -46d 14' 13.9"
with an uncertainty of 1.0 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 69%.
The mask-weighted light curve shows a bright first peak, which is composed
of at least 2 overlapping peaks (at the lower energies), starting at ~T-10 sec
and peaking at ~T+2.5 sec. the first peak never returns to basline before
the second and much weaker peak goes from ~T+12 to T+17 sec.
T90 (15-350 keV) is 13.0 +- 4.0 sec (estimated error including systematics).
The time-averaged spectrum from T-3.1 to T+20.9 sec is best fit by a power law
with an exponential cutoff. This fit gives a photon index 1.25 +- 0.12,
and Epeak of 120 +- 21 keV (chi squared 49.6 for 56 d.o.f.). For this
model the total fluence in the 15-150 keV band is 1.18 +- 0.02 x 10^-5 erg/cm2
and the 1-sec peak flux measured from T+1.86 sec in the 15-150 keV band is
53.9 +- 1.1 ph/cm2/sec. To within the calibration limits, the Band model
fits equally well. A fit to a simple power law gives a photon index
of 1.63 +- 0.03 (chi squared 81.5 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/457330/BA/
GCN Circular 12158
Subject
GRB 110715A: Swift detection of a bright burst with an optical counterpart
Date
2011-07-15T13:26:17Z (15 years ago)
From
Scott Barthelmy at NASA/GSFC <scott@milkyway.gsfc.nasa.gov>
E. Sonbas (GSFC/USRA/Adiyaman Univ.), S. D. Barthelmy (GSFC),
W. H. Baumgartner (GSFC/UMBC), A. P. Beardmore (U Leicester),
D. N. Burrows (PSU), V. D'Elia (ASDC), M. De Pasquale (UCL-MSSL),
P. A. Evans (U Leicester), N. Gehrels (NASA/GSFC),
C. Guidorzi (U Ferrara), S. T. Holland (CRESST/USRA/GSFC),
J. A. Kennea (PSU), H. A. Krimm (CRESST/GSFC/USRA),
N. P. M. Kuin (UCL-MSSL), O. M. Littlejohns (U Leicester),
F. E. Marshall (NASA/GSFC), P. T. O'Brien (U Leicester),
S. R. Oates (UCL-MSSL), C. Pagani (U Leicester),
K. L. Page (U Leicester), P. Romano (INAF-IASFPA),
A. Rowlinson (U Leicester), T. Sakamoto (NASA/UMBC),
M. H. Siegel (PSU), G. Stratta (ASDC), C. A. Swenson (PSU) and
E. Troja (NASA/GSFC/ORAU) report on behalf of the Swift Team:
At 13:13:50 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 110715A (trigger=457330). Swift slewed immediately to the burst.
The BAT on-board calculated location is
RA, Dec 237.660, -46.233 which is
RA(J2000) = 15h 50m 38s
Dec(J2000) = -46d 13' 59"
with an uncertainty of 3 arcmin (radius, 90% containment, including
systematic uncertainty). The BAT light curve showed a double-peaked
structure with a duration of about 15 sec. The peak count rate
was ~70,000 counts/sec (15-350 keV), at ~2 sec after the trigger.
The XRT began observing the field at 13:15:21.9 UT, 90.9 seconds after
the BAT trigger. XRT found a bright, uncatalogued X-ray source located
at RA, Dec 237.6832, -46.2326 which is equivalent to:
RA(J2000) = 15h 50m 43.96s
Dec(J2000) = -46d 13' 57.3"
with an uncertainty of 5.8 arcseconds (radius, 90% containment). This
location is 57 arcseconds from the BAT onboard position, within the BAT
error circle. No event data are yet available to determine the column
density using X-ray spectroscopy.
UVOT took a finding chart exposure of 150 seconds with the White filter
starting 99 seconds after the BAT trigger. There is a candidate afterglow in
the rapidly available 2.7'x2.7' sub-image at
RA(J2000) = 15:50:44.09 = 237.68370
DEC(J2000) = -46:14:06.5 = -46.23513
with a 90%-confidence error radius of about 0.62 arc sec. This position is 9.2
arc sec. from the center of the XRT error circle. The estimated magnitude is
17.34 with a 1-sigma error of about 0.14. No correction has been made for the
expected extinction corresponding to E(B-V) of 0.59.
Burst Advocate for this burst is E. Sonbas (eda.sonbas 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.)