GRB 111008A
GCN Circular 12423
Subject
GRB 111008A: Swift detection of a burst
Date
2011-10-08T22:22:55Z (14 years ago)
From
Scott Barthelmy at NASA/GSFC <scott@milkyway.gsfc.nasa.gov>
C. J. Saxton (UCL-MSSL), S. D. Barthelmy (GSFC),
A. P. Beardmore (U Leicester), 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), C. Pagani (U Leicester),
K. L. Page (U Leicester), D. M. Palmer (LANL) and C. A. Swenson (PSU)
report on behalf of the Swift Team:
At 22:12:58 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 111008A (trigger=505054). Swift slewed immediately to the burst.
The BAT on-board calculated location is
RA, Dec 60.454, -32.689, which is
RA(J2000) = 04h 01m 49s
Dec(J2000) = -32d 41' 18"
with an uncertainty of 3 arcmin (radius, 90% containment, including
systematic uncertainty). The BAT light curve shows 3 sets of peaks
with a total duration of about 70 sec. The peak count rate
was ~4000 counts/sec (15-350 keV), at ~1 sec after the trigger.
The XRT began observing the field at 22:14:29.8 UT, 91.5 seconds after
the BAT trigger. XRT found a bright, uncatalogued X-ray source located
at RA, Dec 60.4491, -32.7098 which is equivalent to:
RA(J2000) = 04h 01m 47.78s
Dec(J2000) = -32d 42' 35.2"
with an uncertainty of 4.9 arcseconds (radius, 90% containment). This
location is 76 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 98 seconds after the BAT trigger. No credible afterglow candidate has
been found in the initial data products. The 2.7'x2.7' sub-image covers 100% of
the XRT error circle. The typical 3-sigma upper limit has been about 19.6 mag.
The 8'x8' region for the list of sources generated on-board covers 100% of the
XRT error circle. The list of sources is typically complete to about 18 mag. No
correction has been made for the expected extinction corresponding to E(B-V) of
0.01.
Burst Advocate for this burst is C. J. Saxton (cjs2 AT mssl.ucl.ac.uk).
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.)
GCN Circular 12424
Subject
GRB 111008A, Swift-BAT refined analysis,
Date
2011-10-09T01:01:29Z (14 years ago)
From
Hans Krimm at NASA-GSFC <hans.a.krimm@nasa.gov>
W. H. Baumgartner (GSFC/UMBC),S. D. Barthelmy (GSFC), J. R. Cummings (GSFC/UMBC),
E. E. Fenimore (LANL), N. Gehrels (GSFC), H. A. Krimm (GSFC/USRA),
C. B. Markwardt (GSFC), D. M. Palmer (LANL), T. Sakamoto (GSFC/UMBC),
C. J. Saxton (UCL-MSSL), M. Stamatikos (OSU), J. Tueller (GSFC),
T. N. Ukwatta (MSU) (i.e. the Swift-BAT team):
Using the data set from T-240 to T+302 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 111008A (trigger #505054)
(Saxton, et al., GCN Circ. 12423). The BAT ground-calculated position is
RA, Dec = 60.439, -32.708 deg which is
RA(J2000) = 04h 01m 45.3s
Dec(J2000) = -32d 42' 29.3"
with an uncertainty of 1.2 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 9%.
The mask-tagged light curve shows three clusters of peaks, each containing at least
two subpeaks, and with returns to the baseline between clusters. Each cluster
is softer and weaker than the one preceding it. The first cluster runs from
T-10 sec to T+10 sec, the second runs from T+28 sec to T+35 sec, and the third
from T+58 to T+65 sec. We note that there is a gap in the telemetry from T+180
to T+240 sec, but there is no indication of any emission between the last peak
and the gap or after the gap. T90 (15-350 keV) is 63.46 +- 2.19 sec (estimated
error including systematics).
The time-averaged spectrum from T-2.64 to T+68.80 sec is best fit by a simple
power-law model. The power law index of the time-averaged spectrum is
1.86 +- 0.09. The fluence in the 15-150 keV band is 5.3 +- 0.3 x 10^-6 erg/cm2.
The 1-sec peak photon flux measured from T+0.04 sec in the 15-150 keV band
is 6.4 +- 0.7 ph/cm2/sec. 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/505054/BA/
GCN Circular 12425
Subject
GRB 111008A: Enhanced Swift-XRT position
Date
2011-10-09T02:49:05Z (14 years ago)
From
Phil Evans at U of Leicester <pae9@star.le.ac.uk>
A.P. Beardmore, P.A. Evans, M.R. Goad and J.P. Osborne (U. Leicester)
report on behalf of the Swift-XRT team.
Using 1125 s of XRT Photon Counting mode data and 1 UVOT
images for GRB 111008A, 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 = 60.45094, -32.70947 which is equivalent
to:
RA (J2000): 04h 01m 48.22s
Dec (J2000): -32d 42' 34.1"
with an uncertainty of 1.7 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 12426
Subject
GRB 111008A: Gemini optical counterpart
Date
2011-10-09T05:21:05Z (14 years ago)
From
Andrew Levan at U.of Leicester <A.J.Levan@warwick.ac.uk>
A.J. Levan (Warwick), K. Wiersema, N.R. Tanvir (Leicester) report
on behalf of a larger collaboration:
"We observed the field of GRB 111008A (Saxton et al. GCN 12423)
with Gemini-South in the r-band. Observations began at 03:12 UT, 5
hours after the BAT trigger. Within the refined XRT error circle
(Beardmore GCN 12425) we locate a single object at
RA(J2000) 04:04:48.24
DEC(J2000) -32:42:33.4
with an error of 0.5" in each axis. Preliminary photometry against
USNO-B1 suggests R~22.8. We suggest this may be the afterglow of
GRB 111008A. Further spectroscopic observations are in progress.
We thank the Gemini staff for the rapid and efficient execution of
these observations."
GCN Circular 12427
Subject
GRB 111008A: NOT optical observation
Date
2011-10-09T06:29:50Z (14 years ago)
From
Dong Xu at Weizmann Inst <dong.dark@gmail.com>
D. Xu (WIS), D. Malesani (DARK/NBI), L.A. Buchhave (NBI), S. Schulze,
P. Jakobsson (U. Iceland) report on behalf of a larger collaboration:
We observed the field of GRB 111008A (Saxton et al., GCN 12423) with
the 2.5m Nordic Optical Telescope (NOT) equipped with ALFOSC. We
obtained 2x600 s R-band images, starting at 04:40:07 UT 9th Oct. 2011
(i.e., 6.45 hr after the burst). The optical afterglow reported in
Levan et al. (GCN 12426) was detected at R ~ 22.3 mag, calibrated
against the #0572-0051383 star (R2=16.77) in the USNO-B1.0 catalog.
GCN Circular 12428
Subject
GRB 111008A, GROND observations
Date
2011-10-09T06:31:49Z (14 years ago)
From
Sylvio Klose at TLS Tautenburg <klose@tls-tautenburg.de>
M. Nardini (Milano Bicocca), S. Klose (TLS Tautenburg), J. Greiner (MPE
Garching), and P. Afonso (MPE/American River College) report on behalf of
the GROND team:
We observed the field of GRB 111008A (Saxton et al., GCN #12423)
simultaneously in g'r'i'z'JHK with GROND (Greiner et al. 2008, PASP 120,
405) mounted at the 2.2 m MPG/ESO telescope at La Silla Observatory
(Chile).
Observations started at 4:30 UT on October 08, 6.3 hours after the GRB
trigger.
We detect a point source within the 1.7 arcsec enhanced Swift-XRT error
circle (Beardmore et al., GCN #12425) at coordinates RA, DEC (J2000) =
04:01:48.25, -32:42:33.2 (+/-0.5"), confirming the observations from
Gemini (Levan et al., GCN 12426).
Preliminary magnitudes at a meantime of 5:15 UT are (in the AB system):
g' > 24.0,
r' = 22.6 +/- 0.1,
i' = 20.9 +/- 0.1,
z' = 19.9 +/- 0.1,
indicating a cosmological g-band dropout.
Data are calibrated against GROND zeropoints. Observations are ongoing.
GCN Circular 12429
Subject
GRB 111008A: Gemini spectroscopic redshift
Date
2011-10-09T06:31:58Z (14 years ago)
From
Andrew Levan at U.of Leicester <A.J.Levan@warwick.ac.uk>
A.J. Levan (Warwick), K. Wiersema, N.R. Tanvir (Leicester) report
for a larger collaboration:
"We obtained optical spectroscopy of the candidate counterpart of
GRB 111008A (Saxton et al. GCN 12423, Levan et al. GCN 12426),
with GMOS on Gemini-South. Observations were centred at 6000A,
and cover the region from 3900-8100A. We see flux from the
candidate afterglow down to ~5500A, and a broad absorption feature
centred at ~7300A, with a brighter continuum red-ward of this. If
interpreted as a DLA then this suggests that the redshift of
GRB 111008A is z~5. We also find weak absorption lines of
Ly-beta, OI(1302), CII(1334) and SiII (1260.5), consistent with a
common redshift of z=5.0.
We note that there was a typographical error in the co-ordinates
of GCN 12426, which should have read
RA(J2000) 04:01:48.24
DEC(J2000) -32:42:33.4
We thank Javier Gorosabel for pointing this error out, and apologise
for any confusion."
GCN Circular 12430
Subject
GRB 111008A: Swift-XRT refined Analysis
Date
2011-10-09T08:52:45Z (14 years ago)
From
Claudio Pagani at U of Leicester <cp232@star.le.ac.uk>
C. Pagani (U Leicester) and C. J. Saxton (UCL-MSSL) report on behalf of
the Swift-XRT team:
We have analysed 5.1 ks of XRT data for GRB 111008A (Saxton et al. GCN
Circ. 12423), from 81 s to 24.0 ks after the BAT trigger. The data
comprise 223 s in Windowed Timing (WT) mode (the first 9 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 Beardmore
et al. (GCN. Circ 12425).
The light curve can be modelled with a series of power-law decays. The
initial decay index is alpha=7.1 (+0.9, -1.0). At T+103 s the decay
flattens to an alpha of 3.22 (+/-0.12). The light curve breaks again at
T+311 s to a decay with alpha=0.26 (+/-0.16), before a final break at
T+4539 s s after which the decay index is 0.99 (+0.12, -0.11).
A spectrum formed from the WT mode data can be fitted with an absorbed
power-law with a photon spectral index of 2.64 (+0.11, -0.10). The
best-fitting absorption column is 8.3 (+1.7, -1.6) x 10^20 cm^-2, in
excess of the Galactic value of 9.8 x 10^19 cm^-2 (Kalberla et al.
2005). The PC mode spectrum has a photon index of 2.02 (+/-0.11) and a
best-fitting absorption column of 4.3 (+2.1, -2.0) x 10^20 cm^-2. The
counts to observed (unabsorbed) 0.3-10 keV flux conversion factor
deduced from this spectrum is 3.5 x 10^-11 (4.0 x 10^-11) erg cm^-2
count^-1.
A summary of the PC-mode spectrum is thus:
Total column: 4.3 (+2.1, -2.0) x 10^20 cm^-2
Galactic foreground: 9.8 x 10^19 cm^-2
Excess significance: 3.6 sigma
Photon index: 2.02 (+/-0.11)
The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/00505054.
This circular is an official product of the Swift-XRT team.
GCN Circular 12431
Subject
GRB 111008A: VLT/X-shooter spectroscopy
Date
2011-10-09T11:03:04Z (14 years ago)
From
Daniele Malesani at Dark Cosmology Centre, Niels Bohr Inst <malesani@dark-cosmology.dk>
K. Wiersema (Univ. Leicester), H. Flores (GEPI/Obs. de Paris), V. D'Elia
(ASI/ASDC & INAF/OAR), P. Goldoni (APC/Univ. Paris 7 & SAp/CEA), D.
Malesani (DARK/NBI), S. D. Vergani (INAF/OABr), A. de Ugarte Postigo
(IAA-CSIC), A. J. Levan (Univ. Warwick), B. Milvang-Jensen, J. P. U.
Fynbo (DARK/NBI), report on behalf of a larger collaboration:
We observed the optical counterpart of GRB 111008A (Saxton et al., GCN
12423; Levan et al., GCN 12426; Xu et al., GCN 12427; Nardini et al.,
GCN 12428), using the X-shooter spectrograph mounted on the ESO-VLT.
Observations started on 2011 October 9.247 UT (7.71 hr after the GRB),
with a total exposure time of 2 hr, covering the wavelength range
3000-25000 AA.
Continuum is clearly detected redwards of ~7600 AA, with several,
strong superimposed absorption features, consistent with a commom
redshift z = 4.9898. Among them, we note several Si II and Fe II
transitions, the CIV doublet, the Mg II doublet (in the H band), and
several fine-structure lines commonly observed in GRB afterglow spectra
(such as Si II*, S II*, O I*). We also note the presence of an
intervening Mg II system at z = 4.61. Our results are thus consistent
with the redshift derived by Levan et al. (GCN 12429; see also Nardini
et al., GCN 12428).
We acknowledge excellent support from the observing staff in Paranal, in
particular Christophe Martayan, Claudio Melo, Leonel Rivas, and Sergio Vera.
GCN Circular 12432
Subject
GRB 111008A: IAC80 I-band observations
Date
2011-10-09T14:05:45Z (14 years ago)
From
Rubén Sánchez-Ramírez at IAA-CSIC <ruben@iaa.es>
R. Sanchez-Ramirez (IAA-CSIC), J. Gorosabel (IAA-CSIC), M. Cebrian (IAC), A.
de Ugarte Postigo (IAA-CSIC, DARK/NBI), P. Monta�es (IAC), A. Rodriguez
Anton (IAC), report on behalf of a larger collaboration:
"We observed the field of GRB 111008A (Saxton et al., GCN Circ 12423) with
the 82cm IAC80 telescope at the Observatorio del Teide, Tenerife, Spain. We
acquired 22 x 300s I-band images on Oct 9.12973 - Oct 9.21239 UT (average
epoch 5.90h after the trigger) . A preliminary analysis of the combined
frame shows the source reported by Levan et al. (GCN Circ 12426) with a
magnitude of I ~ 20.6 (calibrated against USNO-B1 stars)."
GCN Circular 12433
Subject
Konus-Wind observation of GRB 111008A
Date
2011-10-09T14:58:01Z (14 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 long GRB 111008A (Swift-BAT trigger #505054:
Saxton et al., GCN 12433; Baumgartner et al., GCN 12434)
triggered Konus-Wind at T0=79981.676s UT (22:13:01.676)
The burst light curve shows an initial pulse which
peaked at T0+0.256s and a softer weaker pulse at ~T0+30s.
A total burst duration is ~40 s.
The emission is seen up to ~2 MeV.
The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB111008_T79981/
As observed by Konus-Wind the burst
had a fluence of (9.0 � 0.9)x10-6 erg/cm2,
and a 256-ms peak flux, measured from T0+0.256 s,
of (1.4 � 0.3)x10-6 erg/cm2/s
(both in the 20 keV - 2 MeV energy range).
The time-integrated spectrum of the burst
(measured from T0 to T0+41.216 s) is best fitted
in the 20 keV - 2 MeV range by a simple
power-law model with index (2.02 � 0.09),
chi2 = 54.3/59 dof.
The spectrum of the initial pulse
(measured from T0 to T0+8.448 s) is best fitted
in the 20 keV - 2 MeV range by a power law
with exponential cutoff model, for which
alpha = -1.36 (-0.21, +0.24),
and Ep = 149(-28, +52) keV,
chi2 = 38.4/58 dof.
Assuming the redshift z=5.0 (Levan et al., GCN 12429;
Wiersema et al., GCN 12431) 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)x10^53 erg,
the isotropic peak luminosity L_iso_max is (3.8 � 0.7)x10^53 erg/s,
and Ep_rest is 894(-168,+312) keV (the initial pulse spectrum).
All the quoted results are preliminary.
All the quoted errors are at the 90% confidence level.
GCN Circular 12434
Subject
GRB 111008A: Swift/UVOT Upper Limits
Date
2011-10-09T18:37:31Z (14 years ago)
From
Paul Kuin at MSSL <npkuin@gmail.com>
N. P. M. Kuin (MSSL-UCL) and C. J. Saxton (UCL-MSSL)
report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 111008A
99 s after the BAT trigger (Saxton et al., GCN Circ. 12423).
No optical afterglow consistent with the refined XRT position
(Beardmore et al., GCN 12425; see also Levan et al. GCN 12426,
Nardini et al. GCN 12428, and Wiersema et al. GCN 12431) is
detected in the initial UVOT exposures, consistent with the
redshift reported by Levan et al. and Wiersema et al..
Preliminary 3-sigma upper limits using the UVOT photometric system
(Poole et al. 2008, MNRAS, 383, 627) for the first finding chart (FC)
exposure and subsequent exposures are:
Filter T_start(s) T_stop(s) Exp(s) Mag
white_FC 99 249 147 >21.3
u_FC 311 561 246 >20.5
white 99 1359 373 >21.8
v 641 1409 97 >19.0
b 566 1335 78 >19.7
u 311 1310 304 >20.6
w1 690 1457 77 >19.2
m2 666 1433 97 >21.0
w2 617 1385 97 >19.8
The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.01 in the direction of the burst
(Schlegel et al. 1998).
GCN Circular 12436
Subject
EVLA 22 GHz Detection of GRB 111008A
Date
2011-10-13T15:29:15Z (14 years ago)
From
Ashley Zauderer at CfA <bevinashley@gmail.com>
A. Zauderer, E. Berger (Harvard), and D. Frail (NRAO) report:
"We observed the position of GRB 111008A (GCN 12423 ) with the EVLA
beginning 2011 October 10.37 UT (1.4 days after the burst). At 22 GHz,
we detect a radio source consistent with the Swift-XRT error circle (GCN
12425) and the candidate optical counterpart (GCN 12429) at a position of
RA: 04:01:48.24 (+/- 0.04)
Dec: -32:42:32.7 (+/- 0.6)
Further observations are planned."
GCN Circular 12437
Subject
GRB 111008A : miniTAO/ANIR NIR observations
Date
2011-10-14T16:04:57Z (14 years ago)
From
Takeo Minezaki at U.of Tokyo/Astro <minezaki@mtk.ioa.s.u-tokyo.ac.jp>
M. Konishi, K. Tateuchi, K. Motohara, T. Tanabe, T. Kamizuka,
A. Nakashima, T. Minezaki, and Y. Yoshii (University of Tokyo),
S. Komugi (NAOJ/ALMA), S. Manabe (Kobe University),
report on behalf of the TAO project team
We report the near-infrared (NIR) imaging observation of GRB111008A
(Saxton et al., GCN 12423) using NIR Camera ANIR mounted on the
miniTAO 1.0m telescope at the University of Tokyo Atacama Observatory,
located on the summit of Co. Chajnantor (5,640m altitude) in the
northern Chile. Observations started at 04:36 UT on October 09,
approximately 6 hours after the burst.
We detect a point source at the coordinate reported by Levan et al.
(GCN 12426) in the JHKs-bands. The preliminary magnitudes are
J = 19.79 +/- 0.18,
H = 19.47 +/- 0.19,
Ks = 19.38 +/- 0.17,
in AB system.