GRB 120521C
GCN Circular 13348
Subject
GRB 120521C redshift estimate
Date
2012-05-29T22:22:31Z (14 years ago)
From
Nial Tanvir at U.Leicester <nrt3@star.le.ac.uk>
N. R. Tanvir, K. Wiersema (U. Leicester), A. J. Levan (U. Warwick),
A. Cucchiara (UCSC/UCO Lick), D. Perley (Caltech), P. Hirst (Gemini),
T. Carroll, T. Kerr, W. Varricatt (JACH), C. Farina, M. Hrudkova (ING),
L. Ker (Edinburgh) report on behalf of a larger collaboration:
We have combined observations of GRB 120521C (Baumgartner et al. GCN
13318) made using the WHT (Levan et al., GCN 13322), Keck (Perley et al. GCN
13332), UKIRT and Gemini-N telescopes across the optical-IR region in r,i,z,J,H,K.
Analysis of further WHT z-band imaging, obtained at 01:54 UT, 2 hours
after our initial epoch (Levan et al. GCN 13322) shows a faint source
within the XRT error circle. This source is also seen at high confidence
in z-band imaging obtained with Gemini-N at 07:03 UT, and photometry
shows that it brightened by 0.5 magnitudes over this period, suggesting
it is the afterglow of GRB 120521C. This source is only very weakly visible in
contemporaneous I-band imaging obtained with Keck (Perley et al. GCN
13332), and this indicates a red colour i-z >2.3 . However, the source is not
detected in our initial reductions of the UKIRT WFCAM imaging in JHK,
suggesting that z-K < 1.3 (AB, corresponding to f(nu) ~ nu^-beta with
beta<1.3). This is indicative of a high-redshift, rather than a highly
reddened afterglow. We note that the position of the afterglow candidate
in our data matches the radio position reported by Zauderer et al (GCN 13344)
within our calibration uncertainty of ~0.3 arcseconds.
Gemini-North GMOS spectroscopy was obtained in poor conditions, using the
R400 grating centered at 8000 A, giving a wavelength range of
approximately 5850-10100 A. Observations (2 x 1800 s) started at 12:03 UT
on 23 May 2012. We used the GMOS Nod&Shuffle observing mode to improve
skyline subtraction.
In the resulting spectrum, a weak trace is seen at the expected location,
which is only detected redward of ~8700 A. The absence of any emission
bluewards of this wavelength is suggestive of a high redshift of this
source, z~6.0. The low signal of the trace precludes detection of
absorption lines.
Further analysis of the data is ongoing.
GCN Circular 13344
Subject
GRB 120521C: EVLA Localization of Afterglow
Date
2012-05-25T21:39:06Z (14 years ago)
From
Ashley Zauderer at CfA <bevinashley@gmail.com>
A. Zauderer, E. Berger and T. Laskar (Harvard) report on behalf of a
larger collaboration:
"Further to GCN 13343, we note that the EVLA 21.8 GHz brightening source
within the XRT enhanced error circle of GRB 120521C (GCNs 13318, 13324)
is located at (J2000):
RA: 14:17:08.802 (+/- 0.002)
Dec: +42:08:41.22 (+/- 0.02).
This position appears to be offset from the two galaxies at the edge of
the Swift-XRT error circle based on the image provided by Perley et al.
in GCN 13332."
GCN Circular 13343
Subject
GRB 120521C: EVLA 22 GHz Detection
Date
2012-05-25T15:16:06Z (14 years ago)
From
Ashley Zauderer at CfA <bevinashley@gmail.com>
A. Zauderer and E. Berger (Harvard) report on behalf of a larger
collaboration:
"We re-observed the position of GRB 120521C (GCN 13318) on 2012 May
23.12 UT (1.15 d after the burst) with the EVLA at 21.8 GHz. Within
the enhanced Swift-XRT error circle (GCN 13324) we detect a brightening
radio source with a flux density that is about a factor of two above our
early 3-sigma limit of 50 uJy (GCN 13336). We conclude that this is the
radio afterglow of GRB 120521C. Follow-up observations at multiple
frequencies are in progress."
GCN Circular 13337
Subject
GRB 120521C: Early Tautenburg limits
Date
2012-05-22T22:17:24Z (14 years ago)
From
Alexander Kann at TLS Tautenburg <kann@tls-tautenburg.de>
D. A. Kann, B. Stecklum and U. Laux (TLS Tautenburg) report:
We observed to position of Swift GRB 120521C (Trigger 522656, Baumgartner
et al., GCN 13318) with the TLS 1.34m Schmidt telescope. Conditions were
mediocre, with good seeing but bad transparency. Observations were
triggered manually and began 28 minutes after the trigger (17 minutes
after the alert). We obtained 5 x 60 s images in Rc, 4 x 180 s images also
in Rc, and 1 x 600 s each in Z and Ic. The Ic image is affected in depth
by passing clouds.
At the position of the enhanced X-ray afterglow (Beardmore et al., GCN
13324), we do not detect any source, in agreement with earlier results
(Klotz et al., GCN 13319; Bersier et al., GCN 13320; De Cia et al., GCN
13321; Levan et al., GCN 13322; Jelinek et al., GCN 13323; Morgan et al.,
GCN 13325; Gorbovskoy et al., GCN 13329; Oates et al., GCN 13331). The
possible host galaxy (Perley et al., GCN 13332) is not detected.
We us the SDSS star at RA, Dec. (J2000) = 14:17:02.836, +42:6:07.62
(214.26181759, 42.10211787, catalog ID 1237661874023500000) as a
comparison star. Using the transformations of Lupton (2005), we find Rc =
18.33, Ic = 17.93 and Z = 17.78 for this star.
We find the following 2 sigma limiting magnitudes:
Time (days) Exposure (s) Filter UL
0.019827 1 x 60 Rc 21.0
0.022275 5 x 60 Rc 21.8
0.027171 1 x 180 Rc 21.5
0.030760 4 x 180 Rc 22.5
0.040247 1 x 600 Z 20.2
0.048757 1 x 600 Ic 19.3
We note that while the non-detections we as well as other telescopes have
found point to this being a dark GRB, the X-ray absorption seen by Swift
is small. The Keck detection of a possible host galaxy in g' band likely
rules out a high-z interpretation, though.
No further observations are planned.
This message may be cited.
GCN Circular 13336
Subject
GRB 120521C: EVLA 22 GHz Upper Limit
Date
2012-05-22T21:57:19Z (14 years ago)
From
Ashley Zauderer at CfA <bevinashley@gmail.com>
A. Zauderer and E. Berger (Harvard) report on behalf of a larger
collaboration:
"We observed the position of GRB 120521C (GCN 13318) beginning 2012 May
22.12 (3.6 hours after the burst) with the EVLA. At a mean frequency of
21.8 GHz, we find no significant radio emission within the refined
Swift-XRT error circle (GCN 13324) to a 3-sigma limit of ~50 uJy."
GCN Circular 13334
Subject
GRB 120521C: Swift-XRT refined Analysis
Date
2012-05-22T13:46:05Z (14 years ago)
From
Phil Evans at U of Leicester <pae9@star.le.ac.uk>
M.C. Stroh (PSU), D.N. Burrows (PSU), P.A. Evans (U. Leicester), O.M.
Littlejohns (U. Leicester), J.P. Osborne (U. Leicester), A. Maselli
(INAF-IASFPA), V. Mangano (INAF-IASFPA), A. Melandri (INAF-OAB), J.A.
Kennea (PSU) and W.H. Baumgartner report on behalf of the Swift-XRT
team:
We have analysed 7.2 ks of XRT data for GRB 120521C (Baumgartner et
al. GCN Circ. 13318), from 59 s to 29.2 ks after the BAT trigger. The
data comprise 101 s in Windowed Timing (WT) mode (the first 8 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 13324).
The light curve can be modelled with an initial power-law decay with an
index of alpha=2.78 (+0.19, -0.17), followed by a break at T+489 s to
an alpha of 0.51 (+0.11, -0.10).
A spectrum formed from the PC mode data can be fitted with an absorbed
power-law with a photon spectral index of 1.78 (+0.25, -0.16). The
best-fitting absorption column is consistent with the Galactic value
of 1.0 x 10^20 cm^-2 (Kalberla et al. 2005). The counts to observed
(unabsorbed) 0.3-10 keV flux conversion factor deduced from this
spectrum is 3.9 x 10^-11 (4.0 x 10^-11) erg cm^-2 count^-1.
A summary of the PC-mode spectrum is thus:
Total column: 0 (+4.2, -0) x 10^20 cm^-2
Galactic foreground: 1.0 x 10^20 cm^-2
Excess significance: <1.6 sigma
Photon index: 1.78 (+0.25, -0.16)
The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/00522656.
This circular is an official product of the Swift-XRT team.
GCN Circular 13333
Subject
GRB 120521C: Swift-BAT refined analysis
Date
2012-05-22T13:27:34Z (14 years ago)
From
Scott Barthelmy at NASA/GSFC <scott@lheamail.gsfc.nasa.gov>
C. B. Markwardt (GSFC), S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC),
J. R. Cummings (GSFC/UMBC), E. E. Fenimore (LANL), N. Gehrels (GSFC),
H. A. Krimm (GSFC/USRA), 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-240 to T+962 sec from recent telemetry downlinks,
we report further analysis of BAT GRB 120521C (trigger #522656)
(Baumgartner, et al., GCN Circ. 13318). The BAT ground-calculated position is
RA, Dec = 214.288, 42.144 deg, which is
RA(J2000) = 14h 17m 09.1s
Dec(J2000) = +42d 08' 39.8"
with an uncertainty of 1.0 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 67%.
The mask-weighted light curves shows a FRED peak starting at ~T-2 sec,
peaking at ~T+1 sec, abd ending at ~T+40 sec. T90 (15-350 keV) is
26.7 +- 4.4 sec (estimated error including systematics).
The time-averaged spectrum from T-1.03 to T+31.84 sec is best fit by a simple
power-law model. The power law index of the time-averaged spectrum is
1.73 +- 0.11. The fluence in the 15-150 keV band is 1.1 +- 0.1 x 10^-6 erg/cm2.
The 1-sec peak photon flux measured from T-0.02 sec in the 15-150 keV band
is 1.9 +- 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/522656/BA/
GCN Circular 13332
Subject
GRB 120521C: Keck Observations
Date
2012-05-22T12:59:03Z (14 years ago)
From
Daniel Perley at Caltech <dperley@astro.caltech.edu>
D. A. Perley (Caltech), O. Yaron (Weizmann), Y. Cao, and S. R. Kulkarni
(Caltech) report:
We observed the position of GRB 120521C (Baumgartner et al., GCN 13318)
with the Keck I 10m telescope (+LRIS) starting at 10:39 UT on 2012-05-22.
We acquired a total of 1200s of imaging in I-band and 1360s in g-band.
Seeing conditions were relatively poor (1.5").
At the position of the enhanced XRT error circle (Beardmore et al., GCN
13324) we clearly identify a extended source in both the g-band and I-band
images. It appears to consist of at least two components; a red source at
the southern edge of the XRT error circle and a bluer source at the
western edge of the error circle. The relation of these sources to each
other and to GRB 120521C is not yet clear, but they could represent a
host-galaxy merger system, an afterglow superposed on a host, or two
unrelated galaxies at different redshifts.
The early nondetections of an afterglow (e.g. Klotz et al., GCN 13319;
Bersier et al., GCN 13320; De Cia et al., GCN 13321;
Levan et al., GCN 13322; Jelinek et al., GCN 13323; Morgan et al.,
GCN 13325; Gorbovskoy et al., GCN 13329; Oates et al., GCN 13331) are
characteristic of a dark burst. Further observations of this event (in
particular in the NIR) are encouraged.
An image of the field is posted to:
http://www.astro.caltech.edu/~dperley/gcn/120521c/120521c.png
GCN Circular 13331
Subject
GRB 120521C: Swift/UVOT Upper Limits
Date
2012-05-22T11:01:12Z (14 years ago)
From
Samantha Oates at MSSL <sro@mssl.ucl.ac.uk>
S. R. Oates (MSSL-UCL) and W. H. Baumgartner (GSFC/UMBC)
report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 120521C
77 s after the BAT trigger (Baumgartner et al., GCN Circ. 13318).
No optical afterglow consistent with the XRT position
(Beardmore et al., GCN Circ. 13324)
is detected in the initial UVOT exposures.
Preliminary 3-sigma upper limits using the UVOT photometric system
(Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the first
finding chart (FC) exposure and subsequent exposures are:
Filter T_start(s) T_stop(s) Exp(s) Mag
white_FC 77 227 147 >20.9
u_FC 289 539 246 >20.4
white 77 2226 470 >21.7
v 621 2276 194 >19.8
b 546 2201 156 >20.4
u 289 2177 343 >20.7
w1 670 2325 194 >20.4
m2 645 2128 136 >19.9
w2 596 2251 156 >20.4
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 13329
Subject
GRB 120521C: MASTER optical limit
Date
2012-05-22T09:26:17Z (14 years ago)
From
Vladimir Lipunov at Moscow State U/Krylov Obs <gcncirc@observ.inetcomm.ru>
E. Gorbovskoy, V. Lipunov, V.Kornilov, D.Kuvshinov, D.Denisenko,
A.Belinski,
N.Tyurina, N.Shatskiy, P.Balanutsa, D.Zimnukhov, A.Kuznetsov, V.V.Chazov,
A.Kuznetsov
Moscow Lomonosov State University, Sternberg Astronomical Institute,
A. Tlatov, A.V. Parhomenko, D. Dormidontov, V.Sennik
Kislovodsk Solar Station of the Pulkovo Observatory
K.Ivanov, S.Yazev, N.M.Budnev, O.Gres, O.Chuvalaev, V.A.Poleshchuk
Irkutsk State University
V.Yurkov, Yu.Sergienko, D.Varda, E.Sinyakov
Blagoveschensk Educational State University, Blagoveschensk
V.Krushinski, I.Zalozhnich, A. Popov, A. Bourdanov, A. Punanova
Ural Federal University
Hugo Levato and Carlos Saffe
Instituto de Ciencias Astronomicas, de la Tierra y del Espacio (ICATE)
Claudio Mallamaci, Carlos Lopez and Federico Podest
Observatorio Astronomico Felix Aguilar (OAFA)
MASTER II robotic telescope (MASTER-Net: http://observ.pereplet.ru)
located in Kislovodsk was pointed to the GRB120521C 60 sec after notice
time and 715 sec after GRB time at 2012-05-21 23:34:03 UT in two
polarizations. We haven`t found optical
transient within Swift BAT error-box (Baumgartner et al., GCN 13318) .
The 5-sigma upper limit has been about 20.0 mag for mean time after
trigger 1492s (total exposition 1370s).
The direct copy from MASTER DataBase is:
Pro.type Date time Exp.time Limit Filt. Tube.
Alert 2012-05-21 23:34:03 130 17.7 P| EAST
Alert 2012-05-21 23:34:03 130 18.2 P- WEST
Alert 2012-05-21 23:34:03 130 18.2 P- WEST
Alert 2012-05-21 23:36:45 160 18.6 P- WEST
Alert 2012-05-21 23:36:45 160 18.1 P| EAST
Alert 2012-05-21 23:39:48 180 18.9 P- WEST
Alert 2012-05-21 23:39:48 180 18.4 P| EAST
Alert 2012-05-21 23:43:13 180 18.4 P| EAST
Alert 2012-05-21 23:43:13 180 19.0 P- WEST
Alert 2012-05-21 23:46:37 180 18.3 P| EAST
Alert 2012-05-21 23:46:38 180 18.4 P- WEST
Alert 2012-05-21 23:50:02 180 18.4 P| EAST
Alert 2012-05-21 23:50:02 180 19.1 P- WEST
Alert 2012-05-21 23:53:27 180 18.4 P| EAST
Alert 2012-05-21 23:53:27 180 19.1 P- WEST
Alert 2012-05-21 23:56:57 180 18.4 P| EAST
Alert 2012-05-21 23:56:57 180 19.0 P- WEST
AddWest 2012-05-21 23:34:03 1370 20.0 P- WEST
The message may be cited.
GCN Circular 13325
Subject
GRB 120521C: PAIRITEL NIR Upper Limits
Date
2012-05-22T05:44:37Z (14 years ago)
From
Adam Morgan at U.C. Berkeley <qmorgan@gmail.com>
A. N. Morgan (UC Berkeley) reports:
We observed the field of GRB 120521C (Baumgartner et al., GCN 13318)
with the 1.3m PAIRITEL located at Mt. Hopkins, Arizona. Observations
began at 2012-May-22 03h52m27s UT, ~4.5 hours after the Swift trigger.
In mosaics (effective exposure time of 1568 s) taken simultaneously
in the J, H, and Ks filters, we do not detect any source within the
enhanced XRT error circle (Beardmore et al. GCN 13324).
post burst
t_mid (hr) exp.(hr) filt U. Limit (3 sig)
4.99 0.44 J > 18.5
4.99 0.44 H > 17.6
4.99 0.44 Ks > 16.0
All magnitudes are given in the Vega system, calibrated to 2MASS. No
correction for Galactic extinction has been made to the above reported
values.
GCN Circular 13324
Subject
GRB 120521C: Enhanced Swift-XRT position
Date
2012-05-22T05:33:54Z (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 2020 s of XRT Photon Counting mode data and 2 UVOT
images for GRB 120521C, 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 = 214.28648, +42.14467 which is equivalent
to:
RA (J2000): 14h 17m 8.76s
Dec (J2000): +42d 08' 40.8"
with an uncertainty of 2.0 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 13323
Subject
GRB 120521C: BOOTES-1 optical observations
Date
2012-05-22T01:53:37Z (14 years ago)
From
Javier Gorosabel at IAA-CSIC <jgu@iaa.es>
M. Jelinek (IAA-CSIC), P. Kubanek (IP AS CR), A.J. Castro-Tirado
(IAA-CSIC), J. Gorosabel (IAA-CSIC), report on behalf of a larger
collaboration:
"The 0.3-m robotic telescope at the BOOTES-1 station in south Spain
(INTA-CEDEA) responded automatically to GRB 120521C (Baumgartner et al.,
GCN Circ. 13318), performing clear-band observations on May 21.98180 --
21.98863 UT (11.7 -- 21.5 minutes post burst). No object is detected
within the XRT circle down to R~20.5"
GCN Circular 13322
Subject
GRB 120521C: WHT optical observations
Date
2012-05-22T01:20:38Z (14 years ago)
From
Andrew Levan at U.of Leicester <A.J.Levan@warwick.ac.uk>
A.J. Levan (U. Warwick), N.R. Tanvir (U. Leicester), M. Hrudkova (ING) report for a larger collaboration:
"We obtained observations of GRB 120521C (Baumgartner et al. GCN 13318) with the William Herschel Telescope equipped with ACAM in the r and z-bands. Our observations started at 00:01UT, 39 minutes after the burst trigger. We do not detect any afterglow candidates within the XRT error circle. Provisional limits, calibrated against SDSS suggest r>24.0, z>22.5"
GCN Circular 13321
Subject
GRB 120521C - NOT optical limits
Date
2012-05-22T00:56:05Z (14 years ago)
From
Annalisa De Cia at U of Iceland <annalisa@raunvis.hi.is>
A. De Cia (U. of Iceland), A. Sandberg (Oskar Klein Centre), J.Hjorth (DARK), N.R. Tanvir (U. of Leicester) and P. Jakobsson (U. of Iceland) report:
We observed the field of GRB 120521C (Baumgartner et al., GCN 13318) with the NOT equipped with MOSCA in the Sloan r and i filters for 10 minutes, starting at 0:09 UT (47 min after the GRB trigger).
No significant source was detected at the burst position, down to r > 23.6 mag, calibrated against SDSS stars.
GCN Circular 13320
Subject
GRB120521C: Liverpool Telescope observations
Date
2012-05-22T00:45:25Z (14 years ago)
From
David Bersier at Liverpool John Moores U <dfb@astro.livjm.ac.uk>
David Bersier (LJMU) reports on behalf of the Liverpol GRB collaboration:
The Liverpool Telescope responded automatically to Swift trigger 522656
(Baumgartner et al, GCN 13318) 11 minutes after the trigger.
We do not detect any variable source inside the XRT error circle. A
representative upper limit is R=21.5 at 35 minutes after the burst,
calibrated with respect to USNO-B.
GCN Circular 13319
Subject
GRB 120521C: TAROT Calern observatory optical observations
Date
2012-05-22T00:18:05Z (14 years ago)
From
Alain Klotz at CESR-CNRS <Alain.Klotz@free.fr>
Klotz A. (IRAP-CNRS-OMP), Gendre B. (ASDC/INAF-OAR),
Boer M. (UNS-CNRS-OCA), Atteia J.L. (IRAP-CNRS-OMP) report:
We imaged the field of GRB 120521C detected by SWIFT
(trigger 522656) with the TAROT robotic telescope (D=25cm)
located at the Calern observatory, France.
The observations started 23 min after the GRB trigger.
The elevation of the field decreased from
68 degrees above horizon but humidity was higher
than 93% until 23 min after the trigger preventing
the record of the beginning of the event.
We co-added a series of exposures.
No OT was found in the XRT error box (Baumgartner
et al. GCNC 13318).
start stop
23min 37min R > 19.4
Magnitudes were estimated with the nearby USNO-B1 stars
and are not corrected for galactic dust extinction.
This message may be cited.
GCN Circular 13318
Subject
GRB 120521C: Swift detection of a burst
Date
2012-05-21T23:46:02Z (14 years ago)
From
Scott Barthelmy at NASA/GSFC <scott@milkyway.gsfc.nasa.gov>
W. H. Baumgartner (GSFC/UMBC), S. D. Barthelmy (GSFC),
D. N. Burrows (PSU), M. M. Chester (PSU), J. R. Cummings (NASA/UMBC),
V. D'Elia (ASDC), J. A. Kennea (PSU), H. A. Krimm (CRESST/GSFC/USRA),
F. E. Marshall (NASA/GSFC), D. M. Palmer (LANL) and G. Stratta (ASDC)
report on behalf of the Swift Team:
At 23:22:07 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 120521C (trigger=522656). Swift slewed immediately to the burst.
The BAT on-board calculated location is
RA, Dec 214.290, +42.123 which is
RA(J2000) = 14h 17m 09s
Dec(J2000) = +42d 07' 23"
with an uncertainty of 3 arcmin (radius, 90% containment, including
systematic uncertainty). The BAT light curve showed a single FRED
structure with a duration of about 20 sec. The peak count rate
was ~3000 counts/sec (15-350 keV), at ~0 sec after the trigger.
The XRT began observing the field at 23:23:16.8 UT, 69.1 seconds after
the BAT trigger. Using promptly downlinked data we find a bright,
uncatalogued X-ray source located at RA, Dec 214.28671, 42.14311 which
is equivalent to:
RA(J2000) = 14h 17m 08.81s
Dec(J2000) = +42d 08' 35.2"
with an uncertainty of 4.0 arcseconds (radius, 90% containment). This
location is 72 arcseconds from the BAT onboard position, within the BAT
error circle. This position may be improved as more data are received;
the latest position is available at http://www.swift.ac.uk/sper. We
cannot determine whether the source is fading at the present time.
A power-law fit to a spectrum formed from promptly downlinked event
data gives a column density consistent with the Galactic value of 1.05
x 10^20 cm^-2 (Kalberla et al. 2005).
The initial flux in the 2.5 s image was 7.43e-10 erg cm^-2 s^-1 (0.2-10
keV).
UVOT took a finding chart exposure of 150 seconds with the White filter
starting 76 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.
Results from the list of sources generated on-board are not available at this
time. No correction has been made for the expected extinction corresponding to
E(B-V) of 0.01.
Burst Advocate for this burst is W. H. Baumgartner (wayne AT milkyway.gsfc.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.)