GRB 060926
GCN Circular 5901
Subject
GRB 060926: MASTER: discovery of the optical flare
Date
2006-12-07T17:36:35Z (19 years ago)
From
Vladimir Lipunov at Moscow State U/Krylov Obs <gcncirc@observ.inetcomm.ru>
V. Lipunov, V.Kornilov, D.Kuvshinov, N.Tyurina, A.Belinski, E.Gorbovskoy,
A.Krylov, G.Borisov, A.Sankovich, V.Vladimirov, P.Gritsyk
Sternberg Astronomical Institute, Moscow Union 'Optic'
MASTER robotic system (http://observ.pereplet.ru)
responded to GRB060926 (Holland et al., GCN Circ 5612) under the good
conditions (V. Lipunov et al., GCN Circ 5632).
The first image was started at 2006-09-26 16:49:57 UT, 76 s after the GRB
time (355 mm telescope, 6 square degrees FOV, 2.1'' per pix, CCD Alta U16).
The unfiltered image is calibrated relative to USNO A2.0 (0.8 R + 0.2 B).
We find (Lipunov et al., GCN5632) faint OT on the first and on the
coadded images at position:
aplha = 17 35 43.66
dec = 13 02 18.3
err = +- 0.7''
wich coincided with the Holland et al.(GCN Circ 5612) OT position.
We have refind analysis of the images. We discovery optical
flare around 500-700 s after the GRB time (see picture):
Start Mean Exposure Magnitude Flux,
time time time erg/(sm2*sec*eV)
76 s 91 s 30 s 17.3+-0.3 (1,4+-0,3)E-13
150 s 165 s 30 s 18.5+-0.3 (4,6+-1,1)E-14
165 s 343 s 5x30 s 19.3+-0.3 (2,2+-0,5)E-14
255 s 432 s 5x30 s 18.9+-0.3 (3,2+-0,8)E-14
343 s 519 s 5x30 s 18.5+-0.3 (4,6+-1,1)E-14
432 s 608 s 5x30 s 18.3+-0.3 (5,8+-1,3)E-14
519 s 707 s 5x30 s 18.4+-0.3 (5,1+-1,2)E-14
608 s 804 s 5x30 s 18.7+-0.3 (3,9+-0,9)E-14
707 s 1001 s 5x30 s 20.0+-0.3 (1,2+-0,3)E-14
804 s 1200 s 5x30 s 20.1+-0.3 (1,1+-0,3)E-14
901 s 1298 s 5x30 s > 20.1+-0.3 <(1,1+-0,3)E-14
The light curve is available at
http://observ.pereplet.ru/images/GRB060926/light_curve_new.jpg .
Between 91s and 255s a power-law decline with a temporal index
of -1.40+/-0.24 is estimated. Between 707s and 1200s a power-law decline
with a temporal index of -3.30+/-0.70 is estimated. After 1000 s a
power-law decline with a temporal index 0.73 +-0.1 was observed
(A. Stefanescu et al., GCN 5623).
We remember that X-ray flare in GRB 060926 was descovered
by XRT team (M. Perri et al., GCN 5622).
The X-ray spectrum covering the time period from T+67s to T+878s is well
fit by an absorbed power-law with a photon index of 2.1(+/-0.3) and column
density of (2.2+/-0.9)e21 cm**-2 (M. Perri et al., GCN 5622). They note
the Galactic column density in the direction of the source is 7.3e20
cm**-2 .
This means that absorbtion is about 1 magnitude in our band.
The optical-xray data is well fit by power-low with a photon index of
1.7+-0.2 during all our time observation.
We thanks to Dr.K.A.Postnov for usefull discussion and comments.
This work is supported by RFFI 04-02-16411 grant.
This message can be cited.
Mailto: lipunov@sai.msu.ru
GCN Circular 5680
Subject
VLA observations of GRB 060926
Date
2006-10-02T06:28:27Z (19 years ago)
From
Poonam Chandra at U Virginia/NRAO <pc8s@virginia.edu>
P. Chandra (UVA/NRAO) and D. A. Frail (NRAO) report on behalf of
the Caltech-NRAO-Carnegie GRB Collaboration:
"We used the Very Large Array to observe the field of view toward
GRB060926 (GCN 5612) at a frequency of 8.46 GHz on 2006 October
1st starting at 2.07 UT and on 2006 October 2nd starting at 2.00 UT.
The peak radio brightness at the position of the afterglow (GCN 5622) is
-24 uJy � 58 uJy and -18uJy � 56 uJy respectively.
The National Radio Astronomy Observatory is a facility of the National
Science Foundation operated under cooperative agreement by Associated
Universities, Inc."
GCN Circular 5645
Subject
GRB 060926: Swift-UVOT UVW1 Detection Retraction
Date
2006-09-28T14:57:57Z (19 years ago)
From
Pete Roming at PSU <roming@astro.psu.edu>
P. Roming (PSU) and S. T. Holland (GSFC/USRA) report on behalf of the
Swift-UVOT team:
Due to an error in the flux calculation, the reported UVW1 (251 nm) filter
detection in GCN 5625 is not real. No optical afterglow is detected at the
3-sigma level in individual or coadded exposures in this filter. The
3-sigma limiting magnitude for the coadded images is listed below:
Filter T_range(s) Exp(s) Upper Limit (3-sigma)
UVW1 487-11748 1337 20.4
where T_range is the start and end times of the coadded exposures. No
correction has been made for Galactic reddening along the line of sight
(E(B-V) = 0.16). We also point out that the 4.8-sigma level V-filter
detection report in GCN 5625 is real. We apologize for any inconvenience
this error has created.
GCN Circular 5637
Subject
GRB060926: improved redshift
Date
2006-09-27T16:57:45Z (19 years ago)
From
Silvia Piranomonte at OAR <piranomonte@mporzio.astro.it>
V. D'Elia, S.Piranomonte (INAF/OAR), S. Covino (INAF/OABr), D. Malesani
(SISSA/ISAS), F. Fiore, A. Antonelli (INAF/OAR), G. Tagliaferri
(INAF/OABr), L. Stella (INAF/OAR), and G. Chincarini (Univ.
Milano-Bicocca), report on behalf of the MISTICI collaboration:
Using updated calibration files, we have refined the redshift obtained
at the VLT for GRB 060926 (Piranomonte et al., GCN 5626; Holland et al.,
GCN 5612).
We measure a redshift of z = 3.208 based on the detection of the
following lines in absorption: Lyman-alpha, OI_1302 SiII_1304, CII_1334,
CII_1347, SiIV_1393, SiIV_1402, SiII_1526, SiII*_1533, CIV_1540,
CIV_1550, FeII_1608, FeII_1611, AlII_1670, and SiII_1808.
This message can be cited.
GCN Circular 5632
Subject
GRB 060926: MASTER: first minutes decay
Date
2006-09-27T15:54:15Z (19 years ago)
From
Vladimir Lipunov at Moscow State U/Krylov Obs <gcncirc@observ.inetcomm.ru>
V. Lipunov, V.Kornilov, D.Kuvshinov, N.Tyurina, A.Belinski, E.Gorbovskoy,
A.Krylov, G.Borisov, A.Sankovich, V.Vladimirov, P.Gritsyk
Sternberg Astronomical Institute, Moscow Union 'Optic'
MASTER robotic system (http://observ.pereplet.ru)
responded to GRB060926 (Holland et al., GCN Circ 5612) under the good
conditions.
The first image was started at 2006-09-26 16:49:57 UT, 76 s after the GRB
time (355 mm telescope, 6 square degrees FOV, 2.1'' per pix, CCD Alta U16).
The unfiltered image is calibrated relative to USNO A2.0 (0.8 R + 0.2 B).
We find faint OT on the first and on the coadded images at
position:
aplha = 17 35 43.66
dec = 13 02 18.3
err = +- 0.7''
wich coincided with the Holland et al.(GCN Circ 5612) OT position.
Our results:
T-T_grb mean time exp_time m (close to R) S/N
76 s - 106 s 91 s 30 s 17.5+-0.3 4.5
76 s - 360 s 218 s 5x30 s 18.2+-0.3 4
76 s - 820 s 448 s 10x30 s 18.3+-0.3 4
76 s - 1411 s 743 s 15x30 s 18.7+-0.3 4
1024 s - 1810 s 1417 s 10x30 s >19.7
We fitted these values with a powerlaw with a decay index of 0.69 up to 743 s.
This is steeper then the powerlaw OPTIMA-Burst
observations (GCN 5623, A. Stefanescu et al.).
The light curve is available at
http://observ.pereplet.ru/images/GRB060926/lc.jpg .
JPG-Images are available.
Small part with OT:
First - http://observ.pereplet.ru/images/GRB060926/GRB060926_1.jpg
Sum of 5 - http://observ.pereplet.ru/images/GRB060926/GRB060926_5.jpg
Sum of 10 - http://observ.pereplet.ru/images/GRB060926/GRB060926_10.jpg
The 2005 MASTER Survey Image
http://observ.pereplet.ru/images/GRB060926/GRB060926_2005.jpg
Full images:
http://pereplet.sai.msu.ru/nauka/i12.jpg
http://pereplet.sai.msu.ru/nauka/i12a.jpg
http://pereplet.sai.msu.ru/nauka/i12b.jpg
This work is supported by RFFI 04-02-16411 grant.
This message can be cited.
Mailto: lipunov@sai.msu.ru
GCN Circular 5626
Subject
GRB060926: VLT redshift
Date
2006-09-27T03:54:15Z (19 years ago)
From
Silvia Piranomonte at OAR <piranomonte@mporzio.astro.it>
S. Piranomonte (INAF-OAR), S. Covino (INAF/OABr), D. Malesani (SISSA), F. Fiore
(INAF-OAR), G. Tagliaferri (INAF/OABr), G. Chincarini (Univ. Milano-Bicocca), L.
Stella (INAF-OAR), on behalf of the MISTICI collaboration, report:
We observed the optical afterglow of GRB060926 detected by Swift (S.T. Holland
et al., GCN 5612) with ESO's Very Large Telescope UT2 (Kueyen) at Paranal,
Chile. We obtained three FORS1 spectra with a total exposure of 4800 seconds
starting approximately 8 hours after the burst, with the 300V grism and a 1"
slit, providing a wavelength coverage of 3800-8900.
We clearly detect a damped Ly alpha line and various other absorption features
such as Si II,Si IV, CIV at a redshift of z=3.20.
It's a pleasure to thank the excellent support of the Paranal staff,
and in particular that of Hugues Sana.
This message can be cited.
-------------------------------------------------
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GCN Circular 5625
Subject
GRB 060926: Swift-UVOT Detections
Date
2006-09-27T02:20:21Z (19 years ago)
From
Pete Roming at PSU <roming@astro.psu.edu>
P. Roming (PSU) and S. T. Holland (GSFC/USRA) report on behalf of the Swift-UVOT
team:
The Swift UVOT began observing GRB 060926, 57 seconds after the BAT trigger (GCN
5612). We detect a source at the 4.8- and 4.3-sigma levels in the V- and UVW1-
(251 nm) filters, respectively. The magnitude of the source is 19.0+/-0.2
(V-filter) and 18.8+/-0.2 (UVW1-filter) as determined by the Swift analysis
tool, uvotsource.
No optical afterglow is detected at the 3-sigma level in individual or coadded
exposures in the UVOT UVW2-, UVM2-, U-, or B-filters. The 3-sigma limiting
magnitudes for the coadded images of the UVOT filters are listed below:
Filter T_range(s) Exp(s) Upper Limit (3-sigma)
UVW2 551-6405 432 20.1
UVM2 463-10840 1366 20.4
U 511-12283 968 20.8
B 535-6199 422 20.6
where T_range is the start and end times of the coadded exposures. No correction
has been made for Galactic reddening along the line of sight (E(B-V) = 0.16).
No images were taken in the White-filter by the UVOT since bright stars were in
the field-of-view.
GCN Circular 5623
Subject
GRB 060926: OPTIMA-Burst -- further observations
Date
2006-09-27T00:40:02Z (19 years ago)
From
Alexander Stefanescu at MPE <astefan@mpe.mpg.de>
A. Stefanescu, F. Schrey, S. Duscha, G. Kanbach, M. Muehlegger, N.
Primak, H. Steinle (MPE Garching) of the OPTIMA-Burst Team report the
following:
We have observed the OT of GRB 060926 under unfavorable weather
conditions until it became unobservable at ~18:40 UT. To make
comparision easier with GCN 5618 (U. Kiziloglu et al.), we have
callibrated our observations against the R2-magnitudes of 4 nearby
USNO-B1 stars (1030-0324059, 1030-0324042, 1030-0324039, 1030-0324046).
We estimate the magnitude of the OT as follows:
t-t_BAT exp-time
[min] (mid-exp) [s] R_mag
-----------------------------------------------
35.4 600 20.3 +-0.5
59.7 600 20.6 +-0.5
72.7 600 20.7 +-0.7
90.7 2x 1200 21.0 +-0.7
101.2 1200 21.1 +-0.7
We fitted these values with a powerlaw with a decay index of 0.73 +-0.1.
This is significantly shallower than the powerlaw between the MASTER
observations (GCN 5619, V. Lipunov et al.) and ours, with a decay index
of 0.90 +-0.06 - allthough this could be due to incompatibilities in
zero-point.
We thank J. Papamastorakis of the University of Crete and his team for
the possibility to use the 1.3m Telescope at Skinakas Observatory for a
prolonged period of time.
GCN Circular 5622
Subject
GRB 060926: Swift XRT refined analysis
Date
2006-09-27T00:24:50Z (19 years ago)
From
Matteo Perri at ISAC/ASDC <perri@asdc.asi.it>
M. Perri, M. Capalbi, M.L. Conciatore (ASDC), D.N. Burrows (PSU)
and S.T. Holland (GSFC/USRA) report on behalf of the Swift XRT team:
We have analysed the first three orbits of Swift XRT data on the BAT GRB
060926 (Holland, et al., GCN Circ. 5612). A 4.7 ks Photon Counting
mode image provides a refined XRT position:
RA(J2000) = 17h 35m 43.93s
Dec(J2000) = +13d 02' 18.4"
with an uncertainty of 5.9" (90% containment). This is 29.8" away from
the center of the BAT refined position (Cummings et al., GCN Circ. 5621).
This localization lies 11.3" from the XRT position and 4.0" from the
UVOT position quoted in GCN Circ. 5612 (Holland, et al.).
The 0.3-10 keV X-ray light curve during the first orbit shows a flare
at T+430s. Between second and third orbit a power-law decline with a
temporal index of -1.6+/-0.4 is observed.
The X-ray spectrum covering the time period from T+67s to T+878s is
well fit by an absorbed power-law with a photon index of 2.1(+/-0.3)
and column density of (2.2+/-0.9)e21 cm**-2. We note the Galactic
column density in the direction of the source is 7.3e20 cm**-2.
Assuming the X-ray emission continues to decline at the same rate, we
predict a 0.3-10 keV XRT count rate of ~1e-3 count/s at T+24hr, which
corresponds to an observed 0.3-10 keV flux of ~4e-14 erg/cm**2/s.
This circular is an official product of the Swift XRT Team.
GCN Circular 5621
Subject
GRB 060926, Swift-BAT refined analysis
Date
2006-09-26T23:19:19Z (19 years ago)
From
Scott Barthelmy at NASA/GSFC <scott@lheamail.gsfc.nasa.gov>
J. Cummings (GSFC/UMBC), L. Barbier (GSFC), S. D. Barthelmy (GSFC),
E. Fenimore (LANL), N. Gehrels (GSFC), S. T. Holland (GSFC/USRA),
D. Hullinger (BYU-Idaho), H. Krimm (GSFC/USRA), C. Markwardt (GSFC/UMD),
D. Palmer (LANL), A. Parsons (GSFC), T. Sakamoto (GSFC/ORAU),
G. Sato (GSFC/ISAS), M. Stamatikos (GSFC/ORAU), J. Tueller (GSFC)
on behalf of the Swift-BAT team:
Using the data set from T-119 to T+183 sec from recent telemetry downlinks,
we report further analysis of BAT GRB 060926 (trigger #231231)
(Holland, et al., GCN Circ. 5612). The BAT ground-calculated position
is RA,Dec = 263.925, 13.039 deg {17h 35m 41.9s, 13d 2' 21.5"} (J2000)
+- 1.4 arcmin, (radius, sys+stat, 90% containment). The partial coding was 94%.
The mask-weighted lightcuve shows a single FRED peak starting at T-1 sec,
peaking at T+1 sec, and ending approximately at T+10 sec.
T90 (15-350 keV) is 8.0 +- 0.1 sec (estimated error including systematics).
The time-averaged spectrum from T-0.1 to T+8.6 is best fit by a simple
power-law model. The power law index of the time-averaged spectrum is
2.54 +- 0.23. The fluence in the 15-150 keV band is 2.2 +- 0.3 x 10^-7 erg/cm2.
The 1-sec peak photon flux measured from T+0.38 sec in the 15-150 keV band
is 1.1 +- 0.1 ph/cm2/sec. All the quoted errors are at the 90% confidence level.
GCN Circular 5619
Subject
GRB 060926: MASTER OT alert observation
Date
2006-09-26T21:14:12Z (19 years ago)
From
Vladimir Lipunov at Moscow State U/Krylov Obs <gcncirc@observ.inetcomm.ru>
V. Lipunov, V.Kornilov, D.Kuvshinov, N.Tyurina, A.Belinski, E.Gorbovskoy,
A.Krylov, G.Borisov, A.Sankovich, V.Vladimirov, P.Gritsyk
Sternberg Astronomical Institute, Moscow Union 'Optic'
MASTER robotic system (http://observ.pereplet.ru)
responded to GRB060926 (Holland et al., GCN Circ 5612).
The first image was started at 2006-09-26 16:49:57 UT, 76 s after the GRB
time. The unfiltered image is calibrated relative to USNO A2.0 (0.8 R + 0.2 B).
We see OT (Holland et al., GCN Circ 5612).
Our results:
T-T_grb exp_time m (close to R) S/N
76 s - 106 s 30 s >17 5
76 s - 360 s 5x30 s 18+-0.3
76 s - 820 s 10x30 s 18.5+-0.3
Reduction is continued.
Images are available:
http://pereplet.sai.msu.ru/nauka/i12.jpg
http://pereplet.sai.msu.ru/nauka/i12a.jpg
http://pereplet.sai.msu.ru/nauka/i12b.jpg
Small part with OT
http://observ.pereplet.ru/images/GRB060926/GRB060926_5.jpg
http://observ.pereplet.ru/images/GRB060926/GRB060926_10.jpg
This work is supported by RFFI 04-02-16411 grant.
This message can be cited.
Mailto: lipunov@sai.msu.ru
GCN Circular 5618
Subject
GRB 060926: RTT150, UVOT afterglow candidate confirmation
Date
2006-09-26T20:18:53Z (19 years ago)
From
Irek Khamitov at TUG <irekk@tug.tug.tubitak.gov.tr>
U. Kiziloglu (METU), I. Khamitov (TUG), Z. Aslan (TUG),
E. Gogus (Sabanci Uni.),
R. Burenin, M. Pavlinsky, R. Sunyaev (IKI)
I. Bikmaev, N. Sakhibullin (KSU/AST),
report:
We observed the field around the XRT error circle (Holland et al.,
GCN5612) of GRB060926 (Swift trigger 231231) with the Russian-Turkish
1.5-m telescope (RTT150, Bakirlitepe, TUBITAK National Observatory,
Turkey), at the 17:45 UT of Sep 26, about 56 minutes after the burst.
A series of frames (3*300sec) were taken in R band with TFOSC.
At the position of UVOT afterglow candidate (GCN5612) we detect a faint
source which faded more than 1 mag according to early detection
(Stefanescu et al., GCN5614).
Using USNO-B1 star (RA=17:35:42.06, DEC=+13:02:11.7, R2MAG=18.96) we
estimate the following R magnitude for the source:
t-t0 m_R err
(min)
66.5 20.8 0.1
This message may be cited.
GCN Circular 5616
Subject
GRB 060926: BOOTES-IR observations
Date
2006-09-26T20:03:33Z (19 years ago)
From
Antonio Deugarte at IAA-CSIC <deugarte@iaa.es>
A. de Ugarte Postigo (IAA-CSIC Granada) &
P. Kubanek (ASU AV CR ndrejov & ISDC Versoix)
on behalf of a larger collaboration report:
"The 0.6m BOOTES-IR telescope, located at IAA-CSIC Observatorio de
Sierra Nevada in Granada (Spain), observed the SWIFT error box for
GRB 060926 (Holland et al. GCN 5612) starting at 18:48 UT (2.0 h
after the burst) in R-band. We do not detect the optical counterpart
during the first hour of observations down to a limiting 3-sigma
magnitude of R ~ 20.3. Further analysis is ongoing.
This message is quotable."
GCN Circular 5615
Subject
GRB 060926: Watcher observations
Date
2006-09-26T18:07:38Z (19 years ago)
From
John French at UCD,Ireland <jfrench@bermuda.ucd.ie>
J.French (UCD Dublin) and P.Kubanek (AsU AV CR Ondrejov & ISDC Versoix)
report on behalf of the Watcher collaboration:
The Watcher 0.4 m telescope, located at the Boyden Observatory, South
Africa, began observing the location of GRB060926 at 16:49:44 UT (61s
after the burst). Initial observations were carried out under twilight
conditions, restricting Watcher's limiting magnitude for these early 10s
unfiltered exposures to ~ 13mag. We do not detect any new source down to
this limit.
Further observations and analysis are ongoing, as observing conditions
improve.
GCN Circular 5614
Subject
GRB060926 OPTIMA-Burst optical observation
Date
2006-09-26T17:47:29Z (19 years ago)
From
Alexander Stefanescu at MPE <astefan@mpe.mpg.de>
A. Stefanescu, F.Schrey, S. Duscha, G. Kanbach, M. Muehlegger, N.
Primak, H. Steinle (MPE Garching) of the OPTIMA-Burst Team report the
following:
"OPTIMA-Burst at the 1.3m Skinakas Observatory, of the University of
Crete, Greece observed the Swift XRT-errorcircle of GRB 060926 (GCN Circ
5612, S.T. Holland et al.) at 17:19UT (36 min after the Burst,
mid-exposure).
We detected a faint source at the UVOT-Position (GCN Circular #5612). We
estimate the brightness of this source in a 10 min R-Band image as
19.5+-.1mag. There is no source at this position in the USNO-A2 Catalog,
and no minor planet according to MPChecker."
GCN Circular 5613
Subject
GRB 060926: MASTER optical observation
Date
2006-09-26T17:39:22Z (19 years ago)
From
Vladimir Lipunov at Moscow State U/Krylov Obs <gcncirc@observ.inetcomm.ru>
V. Lipunov, V.Kornilov, D.Kuvshinov, N.Tyurina, A.Belinski, E.Gorbovskoy,
A.Krylov,G.Borisov, A.Sankovich, V.Vladimirov, P.Gritsyk
Sternberg Astronomical Institute, Moscow Union 'Optic'
MASTER robotic system (http://observ.pereplet.ru)
responded to GRB060926 (Holland et al., GCN Circ 5612).
The first image was started at 2006-09-26 16:49:57 UT, 76 s after the GRB
time.
The unfiltered image is calibrated relative to USNO A2.0 (0.8 R + 0.2 B).
The robot did not find OT-candidate in error box brighter then 17.0
(s/n=10).
The reduction is continuing.
This work is supported by RFFI 04-02-16411 grant.
This message can be cited.
Mailto: lipunov@sai.msu.ru
GCN Circular 5612
Subject
GRB 060926: Swift detection of a burst
Date
2006-09-26T17:09:22Z (19 years ago)
From
Scott Barthelmy at NASA/GSFC <scott@lheamail.gsfc.nasa.gov>
S. T. Holland (GSFC/USRA), S. D. Barthelmy (GSFC),
D. N. Burrows (PSU), M. Capalbi (ASDC), M.L. Conciatore (ASDC),
J. R. Cummings (NASA/UMBC), N. Gehrels (NASA/GSFC),
C. Guidorzi (Univ Bicocca&INAF-OAB), J. A. Kennea (PSU),
H. A. Krimm (GSFC/USRA), V. Mangano (INAF-IASFPA),
C. B. Markwardt (GSFC/UMD), F. E. Marshall (NASA/GSFC),
J. P. Osborne (U Leicester), K. L. Page (U Leicester),
D. M. Palmer (LANL), P. Romano (INAF-OAB), G. Sato (GSFC/ISAS),
M. Stamatikos (NASA/ORAU), D. E. Vanden Berk (PSU) and
H. Ziaeepour (UCL-MSSL) report on behalf of the Swift Team:
At 16:48:41 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 060926 (trigger=231231). Swift slewed immediately to the burst.
The BAT on-board calculated location is
RA,Dec 263.955, +13.041 {17h 35m 49s, +13d 02' 29"} (J2000)
with an uncertainty of 3 arcmin (radius, 90% containment, including
systematic uncertainty). The BAT light curve shows two overlapping peaks
with a total duration of about 10 sec. The peak count rate
was ~1500 counts/sec (15-350 keV), at ~1 sec after the trigger.
The XRT began taking data at 16:49:41 UT, 60 seconds after the BAT
trigger. The XRT on-board centroid algorithm did not find a source in
the image, however analysis of a 2.5 s exposure in the initial data
products reveals a point source at the following location:
RA(J2000)= 17h 35m 43.2s
Dec(J2000) = +13d 02m 22.1s
with an uncertainty of 12 arcseconds radius (90% confidence). This source is
87 arcseconds from the BAT position.
UVOT took a finding chart exposure of 400 seconds with the V filter starting 57
seconds after the BAT trigger. There is a low significance candidate afterglow
in the rapidly available 2.7'x2.7' sub-image at
RA(J2000) = 17:35:43.66 = 263.9319
DEC(J2000) = +13:02:18.6 = 13.0385
with a 1-sigma error radius of about 0.5 arc sec. This position is 7.6 arc sec.
from the center of the XRT error circle. The estimated magnitude is 19.7 with a
1-sigma error of about 0.5 mag. No correction has been made for the expected
extinction of about 0.5 magnitudes.