GRB 110801A
GCN Circular 12276
Subject
GRB 110801A: Konus-Wind and Swift/BAT joint spectral analysis
Date
2011-08-15T15:05:55Z (15 years ago)
From
Takanori Sakamoto at NASA/GSFC <takanori@milkyway.gsfc.nasa.gov>
T. Sakamoto (GSFC/UMBC), S. D. Barthelmy (GSFC), W. Baumgartner (GSFC/UMBC),
J. Cummings (GSFC/UMBC), E. Fenimore (LANL), N. Gehrels (GSFC),
H. Krimm (GSFC/USRA), C. Markwardt (GSFC/UMD), D. Palmer (LANL),
M. Stamatikos (OSU), J. Tueller (GSFC), and T. Ukwatta (MSU)
V. Pal'shin, S. Golenetskii, R.Aptekar, E. Mazets, D. Frederiks, and
T. Cline on behalf of the Konus-Wind team,
We performed the Konus-Wind and the Swift/BAT joint spectral analysis
of GRB 110801A (Swift/BAT trigger #458521: De Pasquale et al., GCN Circ. 12228,
Barthelmy et al. GCN Circ. 12237). Since the Konus-Wind observed this GRB
in the waiting mode, we only have 3 channel spectral data for the Konus-Wind
which cover the energy range from 20 keV to 1.2 MeV. The joint spectral
analysis of the Konus-Wind and the Swift/BAT data allows us to derive
the broad-band spectral parameters of this burst.
The time interval of the spectral data is chosen from T0(BAT)-26.43 to
T0(BAT)+64.83 sec and from T0(BAT)+332.74 to T0(BAT)+388.67 sec where T0(BAT)
is the trigger time of BAT at 19:49.43 UTC to include two time-separated episodes.
The energy ranges which we used in the joint spectral analysis are 20-1200 keV
and 14-150 keV for the Konus-Wind and the Swift/BAT respectively. The spectral
data of two instruments are fitted with the spectral model multiplied by the
constant factor to take into account the systematic effective area uncertainties
in the response matrices of each instrument.
The spectrum is well fitted with a power-law with exponential cutoff model:
dN/dE ~ E^{alpha}*exp(-(2+alpha)*E/Epeak). The constant factors of each
instrument agree within 10%. No systematic residual from the best fit model is
seen in the spectral data of each instrument (see Sakamoto et al. 2011, PASJ, 63,
215 for the spectral cross-calibration). The best fit spectral parameters are:
alpha = -1.70 (-0.15/+0.12) and Epeak = 140 (-60/+900) keV (chi2/dof = 74/58).
The best fit spectral parameters for the GRB (Band) model fixing beta = -2.5 are:
alpha = -1.70 (-0.15/+0.22), and Epeak = 140 (-50/+1270) keV (chi2/dof = 74/58).
The energy fluence in the 15-1200 keV band calculated by a power-law with
exponential cutoff model for this 147.2 sec interval is 7.3 (-0.9/+ 1.7)x10^-6 erg/cm2.
Assuming z=1.858 (Cabrera Lavers et al. GCN Circ. 12234) and a standard cosmology
model with H_0 = 71 km/s/Mpc, Omega_M = 0.27, Omega_Lambda = 0.73, the isotropic
energy release is E_iso = 1.0 (-0.2/+0.3) x10^53 erg in 1 keV to 10 MeV at the
GRB rest frame extrapolating the best Band function fit fixing beta = -2.5.
All the quoted errors are at the 90% confidence level.
The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB110801A/
GCN Circular 12275
Subject
GRB 110801A: optical observations at Mt. Terskol observatory
Date
2011-08-13T13:40:30Z (15 years ago)
From
Alexei Pozanenko at IKI, Moscow <apozanen@iki.rssi.ru>
M. Andreev, N. Parakhin, A. Sergeev (Terskol Branch of Institute of
Astronomy), A. Pozanenko (IKI) on behalf of larger GRB follow up
collaboration report:
We observed field of the Swift GRB 110801A (Pasquale et al. GCN 12228)
with Zeiss-600 telescope of Mt.Terskol observatory in R filter starting on
Aug. 02 (UT) 00:25. In a stacked image we clearly detect optical afterglow
(Pasquale et al. GCN 12228, Zheng et al. GCN 12229). A photometry is based
on the USNO B1.0 star 1709-0023450 (05 57 24.91 +80 57 39.8) assuming
R=15.73.
T0+ Filter, Exposure, mag.
(mid, d) (s)
0.1951 R 4x180 18.35 +/- 0.10
GCN Circular 12246
Subject
GRB 110801A: optical observations in CrAO
Date
2011-08-04T15:56:39Z (15 years ago)
From
Alexei Pozanenko at IKI, Moscow <apozanen@iki.rssi.ru>
V. Rumyantsev (CrAO), A. Pozanenko (IKI) on behalf of larger GRB follow up
collaboration report:
We observed the field of GRB 110801A (Pasquale et al. GCN 12228) with Shajn
telescope of CrAO observatory on between Aug. 2 (UT) 22:03 and Aug. 3
(UT) 00:27 under variable weather conditions and a mean seeing of 2.1
arsces. We took several frames with exposure of 60 s in R-band. On a stacked
image we detected the optical counterpart (Pasquale et al. GCN 12228, Zheng
et al. GCN 12229). A photometry is based on the USNO B1.0 star 1709-0023450
(05 57 24.91 +80 57 39.8) assuming R=15.73.
T0+ Filter, Exposure, mag. uplim (3 sigma)
(mid, d) (s)
1.1428 R 74x60 21.60 +/- 0.09 23.2
GCN Circular 12241
Subject
GRB 110801A: SAO RAS optical observations
Date
2011-08-03T08:08:25Z (15 years ago)
From
Vladimir Sokolov at SAO RAS <sokolov@sao.ru>
V. V. Sokolov, A. S. Moskvitin, T. A. Fatkhullun, (SAO RAS) report on
behalf of a larger collaboration:
We observed the field of GRB 110801A (De Pasquale et al., GCN 12228)
with the 6-m BTA of SAO RAS (Russia) equipped with the Scorpio.
The observations were carried out in the B and Rc bands
at 00:07:36 -- 00:13:36 UT, August, 02 (since 4.35 hours after the trigger).
The weather conditions were tolerable, seeing around 2".5.
Magnitudes of optical transient are as follows:
B = 19.02 +/- 0.02
R = 18.10 +/- 0.01
Calibration were done against the magnitudes B2 = 16.74 and R2 = 15.73
of the USNO-B.1 star 1709-0023450 (R.A. = 05:57:24.91 Dec.= +80:57:39.8,
Epoch = 2000). The magnitudes of OT were not corrected for the Galactic
extinction E(B-V) = 0.08 in the direction of the burst (Schlegel et al.
1998).
Also we obtained 2 x 600 sec. spectrum (range = 4000 -- 8400A, resolution
FWHM = 10A) at 00:19:54 -- 00:41:24 UT. At the noisy relatively blue
continuum we marginally detected only the C IV absorption line
corresponding to the red shift reported by Cabrera Lavers et al.
(GCN 12234).
The message may be cited.
GCN Circular 12240
Subject
GRB110801A: MITSuME Ishigakijima Optical Observation at 1 day after the burst
Date
2011-08-03T04:58:24Z (15 years ago)
From
Daisuke Kuroda at OAO/NAOJ <dikuroda@oao.nao.ac.jp>
D. Kuroda (OAO, NAOJ), H. Hanayama, T. Miyaji, J. Watanabe (IAO, NAOJ),
K. Yanagisawa (OAO, NAOJ), S.Nagayama (NAOJ), M. Yoshida (Hiroshima),
K. Ohta (Kyoto) and N. Kawai(Tokyo Tech)
report on behalf of the MITSuME collaboration:
We observed the field of GRB 110801A (De Pasquale et al., GCNC 12228)
with the optical three color (g', Rc and Ic) CCD camera attached
to the Murikabushi 1m telescope of Ishigakijima Astronomical
Observatory.
The observation started on 2011-08-02 17:38:02 UT (~21.8 h after the burst).
We detected the previously reported afterglow (Pasquale et al.,
GCNC 12228; Zheng and Guver, GCNC 12229; Guelbenzu et al., GCNC 12230;
Kuroda et al., GCNC 12233) in all the three bands.
Photometric results of the OT are listed below. We used GSC2.3 catalog
for flux calibration.
#T0+[day] MID-UT T-EXP[sec] g' g'_err Rc Rc_err Ic Ic_err
----------------------------------------------------------------------
0.95038 18:38:15 5760.0 21.5 0.3 20.3 0.2 19.1 0.2
----------------------------------------------------------------------
T0+ : Elapsed time after the burst [day]
T-EXP: Total Exposure time [sec]
GCN Circular 12239
Subject
GRB 110801A: Evidence for a jet break
Date
2011-08-02T21:38:15Z (15 years ago)
From
Ana Nicuesa at TLS Tautenburg <ana@tls-tautenburg.de>
A. Nicuesa Guelbenzu, S. Klose, S. Schmidl, A. Rossi, U. Laux, B. Stecklum
(all at TLS Tautenburg) report:
We re-observed the afterglow of GRB 110801A (M. De Pasquale et al., GCN
12228)
with the 2m/1.34m Schmidt telescope of the Thueringer Landessternwarte
Tautenburg starting about 24 hours after the GRB trigger.
A stacking of the first 15 minutes of the second epoch data does not show
the afterglow in the R band down to 21 mag (Vega system). We conclude that
a jet break has occurred within the last 24 hours.
GCN Circular 12238
Subject
GRB 110801A: MASTER OT observations
Date
2011-08-02T17:32:35Z (15 years ago)
From
Vladimir Lipunov at Moscow State U/Krylov Obs <gcncirc@observ.inetcomm.ru>
A.V. Parhomenko, A. Tlatov, D. Dormidontov
Kislovodsk Solar Station of the Pulkovo Observatory
K.Ivanov, V.A.Poleshchuk, S.Yazev, N.M.Budnev, O.Gres,
O.Chuvalaev,E.Konstantinov,
Irkutsk State University
E. Gorbovskoy, V. Lipunov, V.Kornilov, D.Kuvshinov, A.Belinski, N.Tyurina,
N.Shatskiy, P.Balanutsa, V.V.Chazov, P.V.Kortunov, A.Kuznetsov, D.Zimnukhov, M.
Kornilov,A.Sankovich
Sternberg Astronomical Institute, Moscow State University
V.Krushinski, I.Zalozhnich, T.Kopytova, A. Popov
Ural State University, Kourovka
V.Yurkov, Yu.Sergienko, D.Varda, I.Kudelina
Blagoveschensk Educational State University, Blagoveschensk
MASTER II robotic telescope (MASTER-Net: http://observ.pereplet.ru)
located in Tunka(Siberia) was pointed to the GRB110801A 101 sec after GRB
time at 2011-08-01 19:51:23 UT. Unfortunatelly the objects was not in
focus because recently photometer modification. On our first (20s
exposure) set we haven`t found optical transient within SWIFT error-box
(De Pasquale et al., GCN 12228).
The 3-sigma upper limit has been about 14.0 mag (white+polarizator).
MASTER II robotic telescope (MASTER-Net: http://observ.pereplet.ru) located
near Kislovodsk (Caucasus Mountains) closed roof 20 min before
trigger due to cloudy condidtions. The telescope was repointed to the
GRB110901A only 47 min 40 sec after trigger time at 2011-08-01 20:37:22 UT.
We found OT at UVOT postion (De Pasquale et al., GCN 12228).
The results of our photometry are:
Time_Start T_mean-T_trig exp time m error Band
UT s s
20:37:22 2950 180 16.13 0.06 R
20:44:29 3377 180 16.12 0.06 R
20:48:01 3589 180 16.29 0.08 R
20:48:01 3589 180 16.03 0.06 White
20:51:24 3792 180 16.43 0.06 R
20:51:24 3792 180 16.19 0.06 White
23:20:14 12722 180 17.75 0.10 R
The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.08 in the direction of the burst
(Schlegel et al. 1998).
The power low index (F~t^-aplha) apha ~1.0+-0.1 during this
observations in R-band.
The message may be cited.
GCN Circular 12237
Subject
GRB 110801A: Swift-BAT refined analysis
Date
2011-08-02T14:06:06Z (15 years ago)
From
Scott Barthelmy at NASA/GSFC <scott@lheamail.gsfc.nasa.gov>
S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC), J. R. Cummings (GSFC/UMBC),
M. De Pasquale (UCL-MSSL), E. E. Fenimore (LANL), N. Gehrels (GSFC),
H. A. Krimm (GSFC/USRA), C. B. Markwardt (GSFC), D. M. Palmer (LANL),
T. Sakamoto (GSFC/UMBC), G. Sato (ISAS), M. Stamatikos (OSU),
J. Tueller (GSFC), T. N. Ukwatta (MSU)
(i.e. the Swift-BAT team):
Using the data set from T-239 to T+963 sec from recent telemetry downlinks,
we report further analysis of BAT GRB 110801A (trigger #458521)
(De Pasquale, et al., GCN Circ. 12228). The BAT ground-calculated position is
RA, Dec = 89.415, 80.958 deg, which is
RA(J2000) = 05h 57m 39.6s
Dec(J2000) = +80d 57' 28.5"
with an uncertainty of 1.1 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 78%.
The mask-weighted light curve shows two main clusters of peaks. The first
starts at ~T-30 sec, with a maximum at ~T+2 sec, and a long exponental decay
almost down to background before the second cluster. The second cluster
starts ~T+310 sec, peaks at ~T+340 sec, and ending at ~T+550 sec.
T90 (15-350 keV) is 385 +- 10 sec (estimated error including systematics).
The time-averaged spectrum from T-24.2 to T+385.0 sec is best fit by a simple
power-law model. The power law index of the time-averaged spectrum is
1.84 +- 0.10. The fluence in the 15-150 keV band is 4.7 +- 0.3 x 10^-6 erg/cm2.
The 1-sec peak photon flux measured from T+341.78 sec in the 15-150 keV band
is 1.1 +- 0.2 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/458521/BA/
GCN Circular 12236
Subject
Swift/UVOT observations of GRB110801A
Date
2011-08-02T12:52:23Z (15 years ago)
From
Massimiliano de Pasquale at MSSL-UCL <mdp@mssl.ucl.ac.uk>
M. De Pasquale (MSSL-UCL) reports on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 110801A
109 s after the BAT trigger (De Pasquale et al., GCN Circ. 12228).
A source consistent with the XRT position (Evans et al., GCN Circ. 12232)
is detected in the initial and summed UVOT exposures, except in um2
filter and a detection in uw2, at 2 sigma confidence level. Since
the redshift of this event is 1.86 (Cabrera Lavers, GCN Circ. 12234),
we think the weak detection in uw2 is due to flux in the reddest part
of this filter.
The refined UVOT position is:
RA (J2000) = 05:57:44.87 = 89.43695 (deg.)
Dec (J2000) = +80:57:21.1 = 80.95592 (deg.)
with an estimated uncertainty of 0.51 arc sec. (radius, 90% confidence).
The afterglow shows a quick rise from the first exposure up to ~300s.
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 (fc) 109 259 147 18.06 � 0.07
white 109 6337 727 17.23 � 0.05
v 598 6747 451 17.07 � 0.06
b 523 6132 432 17.47 � 0.05
u (fc) 267 517 246 15.89 � 0.05
u 267 5927 488 15.68 � 0.04
w1 647 5722 255 17.92 � 0.11
m2 622 6904 404 >20.2
w2 573 6543 452 20.48 � 0.41
The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.08 in the direction of the burst
(Schlegel et al. 1998).
GCN Circular 12235
Subject
GRB 110801A: Swift-XRT refined Analysis
Date
2011-08-02T09:00:16Z (15 years ago)
From
Andy Beardmore at U Leicester <apb@star.le.ac.uk>
A.P. Beardmore (U. Leicester) and M. De Pasquale (UCL-MSSL) report on
behalf of the Swift-XRT team:
We have analysed 9.9 ks of XRT data for GRB 110801A (De Pasquale et
al. GCN Circ. 12228), from 89 s to 24.0 ks after the BAT trigger. The
data comprise 566 s in Windowed Timing (WT) mode (the first 7 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 12232).
The light curve initially shows a number of flares, the largest peaking
at 500-600 count/s between T+355 s and T+390 s after the trigger. Once
this flare has decayed, the light curve after T+800 s can be modelled
by a power-law with a slope of 1.12 +/- 0.06.
A spectrum formed from the WT mode data can be fitted with an absorbed
power-law with a photon spectral index of 1.754 (+0.025, -0.026). The
best-fitting absorption column is 6.4 (+/-0.6) x 10^21 cm^-2, at a
redshift of 1.858, in addition to the Galactic value of 6.2 x 10^20
cm^-2 (Kalberla et al. 2005). We note this spectrum includes strong
spectral evolution through the flare. The PC mode spectrum has a photon
index of 2.04 (+/-0.09) and a best-fitting absorption column of 1.6
(+1.6, -1.4) x 10^21 cm^-2. The counts to observed (unabsorbed) 0.3-10
keV flux conversion factor deduced from this spectrum is 3.6 x 10^-11
(4.5 x 10^-11) erg cm^-2 count^-1.
A summary of the PC-mode spectrum is thus:
Galactic foreground: 6.2 x 10^20 cm^-2
Intrinsic column: 1.6 (+1.6, -1.4) x 10^21 cm^-2 at z=1.858
Photon index: 2.04 (+/-0.09)
The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/00458521.
This circular is an official product of the Swift-XRT team.
GCN Circular 12234
Subject
GRB 110801A: Afterglow redshift from 10.4m GTC
Date
2011-08-02T06:33:02Z (15 years ago)
From
Antonio Deugarte at IAA-CSIC <deugarte@iaa.es>
A. Cabrera Lavers (GTC), A. de Ugarte Postigo (DARK/NBI), A.J.
Castro-Tirado, J. Gorosabel, C.C. Thoene (IAA-CSIC), R. Dom�nguez (GTC)
report on behalf of a larger collaboration:
We have observed the afterglow of GRB 110801A (De Pasquale et al. GCNC
12228) using OSIRIS at the 10.4m GTC telescope (La Palma, Spain).
Observations consisted on 2x900s + 1x600s exposures using the R1000B
grating (resolution ~1000) with coverage between 3600 and 7500 Angstrom.
Observations started at 3:30 UT (7.7h after the burst). In a preliminary
analysis, using archival calibrations, we detect a high signal to noise
ratio continuum with absorption features that include CII, SiIV, SiII,
CIV, FeII, AlII, AlIII, NiII, ZnII, and MnII, as well as fine structure
FeII* and NiII* at a common redshift of z=1.858, which we identify as the
redshift of the afterglow. We also identify two intervening systems at
z=1.246 and z=0.745 through the presence of the MgII doublet.
GCN Circular 12233
Subject
GRB110801A: MITSuME Ishigakijima Optical Observation
Date
2011-08-02T05:13:46Z (15 years ago)
From
Daisuke Kuroda at OAO/NAOJ <dikuroda@oao.nao.ac.jp>
D. Kuroda (OAO, NAOJ), H. Hanayama, T. Miyaji, J. Watanabe (IAO, NAOJ),
K. Yanagisawa (OAO, NAOJ), S.Nagayama (NAOJ), M. Yoshida (Hiroshima),
K. Ohta (Kyoto) and N. Kawai(Tokyo Tech)
report on behalf of the MITSuME collaboration:
We observed the field of GRB 110801A (Pasquale et al., GCNC 12228)
with the optical three color (g', Rc and Ic) CCD camera attached
to the Murikabushi 1m telescope of Ishigakijima Astronomical
Observatory.
The observation started on 2011-08-01 19:53:51 UT (~4 min after the burst).
We detected the previously reported afterglow (Pasquale et al.,
GCNC 12228; Zheng and Guver, GCNC 12229; Guelbenzu et al., GCNC 12230)
in all the three bands.
Photometric results of the OT are listed below. We used GSC2.3 catalog
for flux calibration.
#T0+[day] MID-UT T-EXP[sec] g' g'_err Rc Rc_err Ic Ic_err
----------------------------------------------------------------------
0.00323 19:54:21 60.0 16.16 0.07 15.14 0.04 14.44 0.04
0.00404 19:55:31 60.0 15.35 0.06 14.29 0.04 13.57 0.04
0.00485 19:56:41 60.0 15.38 0.06 14.28 0.04 13.56 0.04
0.00731 20:00:14 60.0 15.54 0.06 14.51 0.04 13.79 0.04
0.00976 20:03:45 60.0 15.71 0.07 14.67 0.04 13.98 0.04
0.01222 20:07:18 60.0 15.77 0.07 14.79 0.04 14.12 0.04
0.01466 20:10:48 60.0 15.89 0.07 14.91 0.04 14.24 0.04
----------------------------------------------------------------------
T0+ : Elapsed time after the burst [day]
T-EXP: Total Exposure time [sec]
GCN Circular 12232
Subject
GRB 110801A: Enhanced Swift-XRT position
Date
2011-08-02T02:01:09Z (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 1989 s of XRT Photon Counting mode data and 5 UVOT
images for GRB 110801A, 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 = 89.43603, +80.95615 which is equivalent
to:
RA (J2000): 05h 57m 44.65s
Dec (J2000): +80d 57' 22.2"
with an uncertainty of 1.8 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 12230
Subject
GRB 110801A: TLS Optical afterglow confirmation
Date
2011-08-01T21:22:52Z (15 years ago)
From
Ana Nicuesa at TLS Tautenburg <ana@tls-tautenburg.de>
GRB 110801A: TLS Optical afterglow Confirmation
A. Nicuesa Guelbenzu, X. Luo, S. Klose, U. Laux, B. Stecklum (all
at TLS Tautenburg) report:
We observed the afterglow of GRB 110801A (M. De Pasquale et al., GCN 12228)
with the 2m/1.34m Schmidt telescope of the Thueringer
Landessternwarte Tautenburg starting about 20 min after the GRB trigger.
The afterglow is clearly detected in the R band images at the position
of the UVOT detection.
We confirm the re-brightening of the afterglow as reported by
ROTSE III (Zheng et al. 2011, GCN 12229).
GCN Circular 12229
Subject
GRB 110801A: ROTSE-III Detection of re-brightening from OT
Date
2011-08-01T21:15:02Z (15 years ago)
From
Weikang Zheng at U.of Michigan <zwk@umich.edu>
GRB 110801A: ROTSE-III Detection of re-brightening from OT
W. Zheng (U Mich), T. Guver (U Arizona), report on behalf of the ROTSE
collaboration:
ROTSE-IIId, located at the Turkish National Observatory at Bakirlitepe,
Turkey, responded to GRB 110801A (Swift trigger 458521; Pasquale et al.
GCN 12228). The first image was at 19:52:57.7 UT, 194.7 s after the
burst. The unfiltered images are calibrated relative to USNO A2.0.
We detect the OT at UVOT location (GCN 12228), the OT appeared
to be re-brightening to ~15.0 mag at ~1400s after the burst.
Continuing observations are in progress.
[GCN OPS NOTE(01aug11): Per author's request (at GCN's request),
the language was changed to remove the implication that the delay
in observing was tied to the Notice arrival time. The delay was due
to weather and dome operations. The "(8.7 s after the GCN notice time)"
was removed from the text.]
GCN Circular 12228
Subject
GRB 110801A: Swift detection of a burst with an optical counterpart
Date
2011-08-01T20:01:04Z (15 years ago)
From
Scott Barthelmy at NASA/GSFC <scott@milkyway.gsfc.nasa.gov>
M. De Pasquale (UCL-MSSL), S. D. Barthelmy (GSFC),
W. H. Baumgartner (GSFC/UMBC), A. P. Beardmore (U Leicester),
D. N. Burrows (PSU), J. R. Cummings (NASA/UMBC),
P. A. Evans (U Leicester), N. Gehrels (NASA/GSFC),
S. T. Holland (CRESST/USRA/GSFC), E. A. Hoversten (PSU),
J. A. Kennea (PSU), A. Melandri (INAF-OAB),
C. J. Mountford (U Leicester), K. L. Page (U Leicester),
D. M. Palmer (LANL), T. Sakamoto (NASA/UMBC),
B. Sbarufatti (INAF-OAB/IASFPA), M. H. Siegel (PSU),
E. Sonbas (GSFC/USRA/Adiyaman Univ.), C. A. Swenson (PSU),
E. Troja (NASA/GSFC/ORAU) and T. N. Ukwatta (MSU) report on behalf of
the Swift Team:
At 19:49:42 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 110801A (trigger=458521). Swift slewed immediately to the burst.
The BAT on-board calculated location is
RA, Dec 89.285, +80.988 which is
RA(J2000) = 05h 57m 08s
Dec(J2000) = +80d 59' 18"
with an uncertainty of 3 arcmin (radius, 90% containment, including
systematic uncertainty). The BAT light curve shows a few weak peaks
with a duration of about 70 sec. The peak count rate
was ~700 counts/sec (15-350 keV), at ~1 sec after the trigger.
The XRT began observing the field at 19:51:21.9 UT, 98.9 seconds after
the BAT trigger. XRT found a bright, uncatalogued X-ray source located
at RA, Dec 89.4307, +80.9548 which is equivalent to:
RA(J2000) = 05h 57m 43.36s
Dec(J2000) = +80d 57' 17.2"
with an uncertainty of 4.9 arcseconds (radius, 90% containment). This
location is 146 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 108 seconds after the BAT trigger. There is a candidate afterglow in
the rapidly available 2.7'x2.7' sub-image at
RA(J2000) = 05:57:44.73 = 89.43637
DEC(J2000) = +80:57:21.6 = 80.95600
with a 90%-confidence error radius of about 0.62 arc sec. This position is 5.4
arc sec. from the center of the XRT error circle. The estimated magnitude is
18.03 with a 1-sigma error of about 0.14. No correction has been made for the
expected extinction corresponding to E(B-V) of 0.08.
Burst Advocate for this burst is M. De Pasquale (mdp 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.)