GRB 091020
GCN Circular 10231
Subject
GRB 091020: MASTER-Net optical polarization observations
Date
2009-12-02T19:15:38Z (16 years ago)
From
Vladimir Lipunov at Moscow State U/Krylov Obs <gcncirc@observ.inetcomm.ru>
E. Gorbovskoy, V. Lipunov, V.Kornilov, A.Belinski, N.Shatskiy, N.Tyurina,
D.Kuvshinov, P.Balanutsa, V.V.Chazov, P.V.Kortunov, A.Kuznetsov,
D.Zemnukhov, M. Kornilov
Sternberg Astronomical Institute, Moscow State University
V.Krushinski, I.Zalozhnih, T.Kopytova
Ural State University, Kourovka
A. Tlatov, A.V. Parhomenko, D. Dormidontov
Kislovodsk Solar Station of the Pulkovo Observatory
K.Ivanov, S.Yazev, N.M.Budnev, E.Konstantinov, V.Lenok
Irkutsk State University
S.Sergienko, V.Yurkov
Blagoveschensk Educational State University, Blagoveschensk
MASTER II robotic telescope (MASTER-Net: http://observ.pereplet.ru, 2x400
mm, 2x 4 square degrees, 2x16Mpx Apogee CCD) located
at Kislovodsk was pointed to the GRB 091020 (Racusin et al., GCN 10048)
by internet 3422 s after the GRB time. The
large delay was caused with technical problems on site (Gorbovskoy et
al., GCN 10052).
The first 7 images was taken in R-band. The exposure each images is 180s.
West-telescope
GRB Time OT Mag Error
1.02097639 17.93 0.22
1.07643278 17.43 0.09
1.13188834 17.78 0.14
1.18734417 18.03 0.19
1.24280056 17.87 0.15
1.29825584 17.58 0.10
1.35371584 17.94 0.12
The result of the unfiltred polarization combined images is:
West-telescope
GRB Time OT Mag Error
(Hours)
1.604558 18.65 0.10
1.983004 18.91 0.08
2.285582 19.04 0.08
2.562864 19.28 0.11
2.84015 19.36 0.09
3.117435 19.32 0.08
3.394721 19.35 0.06
3.672004 19.23 0.10
3.949285 20.07 0.16
4.226602 20.67 0.28
4.503883 20.07 0.22
East-telescope
GRB Time GRB Error
(Hours)
1.604718 18.60 0.06
1.983232 18.46 0.06
2.285826 19.14 0.09
2.563109 19.11 0.09
2.84039 19.56 0.10
3.117671 19.38 0.09
3.394954 19.70 0.17
3.672234 19.53 0.11
3.949516 19.92 0.16
4.226796 20.03 0.19
4.50408 19.99 0.16
Using all our polarizated magnitudes we
find that the light curve is very well described by a
single power-law decay with alpha = 1.2 +/- 0.1, that is in good agreement
with the following observations (Kann et al., GCN 10076)
The light curve of our observations is available at
http://observ.pereplet.ru/images/GRB091020/grb.html .
The message may be cited.
mailto: lipunov@sai.msu.ru
GCN Circular 10095
Subject
GRB 091020: Fermi GBM observation
Date
2009-10-28T14:27:17Z (16 years ago)
From
Vandiver Chaplin at UAH/Fermi-GBM <chapliv@email.uah.edu>
V.Chaplin (UAH) reports on behalf of the Fermi GBM Team:
"At 21:36:43.82 UT on 20 October 2009, the Fermi
Gamma-Ray Burst Monitor triggered on GRB 091020
(trigger 277767405 / 091020900), which was also detected by
the Swift-BAT (Racusin et al., GCN 10048).
The angle from the Fermi LAT boresight of the Swift-XRT position
(Beardmore et al., GCN 10050) is 118 degrees.
The GBM light curve consists of a single pulse
with a duration (T90) of about 37 s (8-1000 keV).
The time-averaged spectrum from T0-7.7 s to T0+21 s is
best fit by a Band function with Epeak = 47.9 +/- 7.1 keV,
alpha = 0.2 +/- 0.4, and beta = -1.7 +/- .02.
The event fluence (8-1000 keV) in this time interval is
(1.0 +/- 0.2)E-05 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+1.5 s in the 8-1000 keV band
is 7.4 +/- 0.5 ph/s/cm^2.
The spectral analysis results presented above are preliminary;
final results will be published in the GBM GRB Catalog."
GCN Circular 10090
Subject
GRB 091020: Late TLS detection
Date
2009-10-27T02:31:21Z (16 years ago)
From
Alexander Kann at TLS Tautenburg <kann@tls-tautenburg.de>
D. A. Kann, U. Laux, M. Roeder & H. Meusinger (TLS Tautenburg) report:
We observed again the afterglow of the Swift GRB 091020 (Racusin et al.,
GCN 10048) with the 1.34m Schmidt telescope of the Thueringer
Landessternwarte Tautenburg, Germany, on the 26th of October, 5.2 days
after the GRB. We obtained 11 x 600 sec images in Rc before clouds shut us
down again. At the position of the afterglow, we detect a faint source in
the stacked image.
We derive the following afterglow magnitudes using the same comparison
star as Kann et al., GCN 10076:
dt Filter mag dmag
____________________________________
5.213357 Rc 23.62 0.31
Kann et al., GCN 10076, found a single power-law decay with alpha = 1.12
+/- 0.06. Compared to the extrapolation of this fit, there is no
significant evidence for a break yet.
No further observations are possible due to an instrument change.
This message may be cited.
GCN Circular 10088
Subject
Radio afterglow detection from GRB 091020
Date
2009-10-26T23:00:25Z (16 years ago)
From
Dale A. Frail at NRAO <dfrail@nrao.edu>
Dale A. Frail (NRAO), Poonam Chandra (RMC), and Tanay Singh
report on behalf of a larger collaboration:
"We used the Very Large Array (VLA) to observe the field of view
towards the Swift burst GRB 091020A (GCN 10048, 10050, 10051) at a
frequency of 8.46 GHz. Data has been taken at 6 different epochs:
October 21.66, 22.54, 22.77, 22.99, 24.60 and 26.71 UT. The average
flux density of the source during the first 4 epochs was 108 +/- 25
uJy. The source has since increased in flux, rising to 230 +/- 42 uJy
on Oct 24.60 UT and 436 +/- 42 uJy on Oct. 26.71 UT. Our current
best-fit position is (J2000) R.A.=11:42:55.268, Dec.=+50:58:41.36 with
a conservative error of +/-0.6". Further observations are planned.
The National Radio Astronomy Observatory is a facility of the National
Science Foundation operated under cooperative agreement by Associated
Universities, Inc."
GCN Circular 10080
Subject
GRB 091020 : Xinglong TNT upper limit
Date
2009-10-26T12:31:47Z (16 years ago)
From
L.P. Xin at NAOC <xlp@bao.ac.cn>
L.P. Xin, X.F. Wang, J. Wang, Y.L. Qiu, J.Y. Wei,
W.K. Zheng, J.S. Deng, and C. Wu, J.Y. Hu
on behalf of EAFON report:
We observed the optical afterglow of GRB 091020
(e.g. Racusin et al., GCN 10048; Gorbovskoy et al.,
GCN 10052; Perley GCN 10060) with Xinglong TNT
telescope from Oct. 22, 20:27:52(UT),1.952 days
after the burst. The optical afterglow (Gorbovskoy
et al., GCN 10052; Perley GCN 10060) was not detected
in our combined image with a duration of 7*600 sec.
The upper limit is estimated to be R~21.4 mag
from USNO-B1.0 R2 magnitude, at the mean time of
1.974 days since the trigger.
This message may be cited.
For more information about Xinglong GRBs Follow-up
observations, please visit the web-site:
http://www.xinglong-naoc.org/grb/
GCN Circular 10076
Subject
GRB 091020: Early TLS Multicolor detections, red afterglow
Date
2009-10-25T05:58:15Z (16 years ago)
From
Alexander Kann at TLS Tautenburg <kann@tls-tautenburg.de>
D. A. Kann, U. Laux, M. Roeder & H. Meusinger (TLS Tautenburg) report:
We observed the afterglow of the Swift GRB 091020 (Racusin et al., GCN
10048) with the 1.34m Schmidt telescope of the Thueringer Landessternwarte
Tautenburg, Germany, as soon as it had risen to an airmass of
2.2, starting 0.167 days after the GRB. We obtained 3 x 300 sec images in
Z, Ic, Rc, V and B each. We detect the afterglow in all single images.
As a comparison star, we use the SDSS star at:
RA (J2000) = 11:42:49.2 (175.7050129)
Dec. (J2000) = +51:00:52.42 (+51.01456163)
For this star, using the transformation equations of Lupton (2005) (taking
the mean of the two transformation equations each), and transforming the
z' value to Vega mags following Fukugita (1995), we derive the
magnitudes:
B = 19.109
V = 17.740
Rc = 16.759
Ic = 15.927
Z = 15.563
We derive the following afterglow magnitudes:
dt Filter mag dmag
____________________________________
0.166947 Z 18.17 0.13
0.170987 Z 18.10 0.13
0.175038 Z 18.16 0.13
0.179181 Ic 18.45 0.06
0.183221 Ic 18.30 0.05
0.187260 Ic 18.32 0.05
0.191404 Rc 19.43 0.04
0.195444 Rc 19.40 0.04
0.199483 Rc 19.40 0.04
0.203627 V 19.90 0.10
0.207666 V 20.00 0.10
0.211706 V 20.06 0.10
0.215849 B 20.78 0.10
0.219889 B 20.71 0.08
0.223928 B 20.72 0.08
Using further reported magnitudes (Oates et al., GCN 10054; Gorbovskoy et
al., GCN 10052, Xu et al., GCN 10053, Perley, GCN 10058, GCN 10060), we
find that the Rc band light curve is very well described by a
single power-law decay with alpha = 1.12 +/- 0.06, B and V light curves
agree with an achromatic light curve evolution. We find a red afterglow
with spectral slope beta ~ 2, and note that the Ic - Z color is
very blue, this may be due to a filter mismatch between the SDSS z' filter
and our Z filter.
This message may be cited.
GCN Circular 10060
Subject
GRB 091020: Additional Lick observations
Date
2009-10-22T14:22:00Z (16 years ago)
From
Daniel Perley at U.C. Berkeley <dperley@astro.berkeley.edu>
D. A. Perley (UC Berkeley) reports:
Further to observations the previous night (GCN 10058), I re-observed
the afterglow of GRB 091020 between UT 2009-10-22 12:23 and 13:25 using
the Nickel 40-inch telescope at Lick Observatory in a series of
seventeen 180 second exposures (51 minutes total integration) in R-band.
The afterglow is detected in in the combined stack of all frames.
Calibrating relative to the same SDSS standard stars as in GCN 10058,
the estimated magnitude of the afterglow at this time is:
R = 21.81 +/- 0.23 mag (t_mid = 39.29 hr)
The implied average decay index over the 24 hours since the previous
observation is alpha=0.87.
GCN Circular 10059
Subject
Konus-Wind observations of GRB 091020 (correction to GCN 10057)
Date
2009-10-21T14:24:40Z (16 years ago)
From
Dmitry Frederiks at Ioffe Institute <fred@mail.ioffe.ru>
Dmitry Frederiks reports:
I made a mistake in the subject line of GCN 10057:
it should be "Konus-Wind observations of GRB 091020"
instead of "Konus-Wind observations of GRB 091010".
I apologize for the confusion.
GCN Circular 10058
Subject
GRB 091020: Lick observations
Date
2009-10-21T14:24:31Z (16 years ago)
From
Daniel Perley at U.C. Berkeley <dperley@astro.berkeley.edu>
D. A. Perley (UC Berkeley) reports:
I observed the location of GRB 091020 (Racusin et al, GCN 10048)
starting at UT 2009-10-21 12:30 using the Nickel 40-inch telescope at
Lick Observatory. A series of nine exposures in R-band were acquired,
followed by five exposures in I-band and an additional sequence in
R-band during morning twilight. All exposures except for the first were
of 180 seconds duration.
The afterglow is marginally detected in individual frames and
well-detected in a combined stack. Calibrating relative to five nearby
SDSS standard stars transformed to R-band using the transformation
equation of Lupton (2005), the estimated magnitude of the afterglow in
the first R-band stack is:
R = 20.91 +/- 0.13 mag (t_mid = 15.17 hr)
Additional follow-up is planned if weather permits.
GCN Circular 10056
Subject
GRB 091020: Swift-XRT refined analysis
Date
2009-10-21T14:08:47Z (16 years ago)
From
Andy Beardmore at U Leicester <apb@star.le.ac.uk>
A. P. Beardmore, P. A. Evans (U. Leicester) and J. L. Racusin
(NASA/GSFC/ORAU) report on behalf of the Swift-XRT team:
We have analysed 13 ks of Swift-XRT data for GRB 091020 (Racusin et
al., GCN Circ. 10048), from 87 s to 29.6 ks after the BAT trigger
(#373458). The data comprise 350 s in Windowed Timing (WT) mode with
the remainder in Photon Counting (PC) mode. The enhanced XRT position
for this burst was given by Beardmore et al. (GCN. Circ 10050).
The light curve shows an initial steep decay with an index of 3.7 +/-0.6,
breaking at T+130 s to a shallower decay of slope 0.90 +/- 0.03, with a
small flare superimposed at T+190s. A further break to a decay slope of
1.39 +/- 0.1 is apparent at T+6.6 ks.
The WT mode spectrum, from 87 s to 434 s after the trigger, can be fit
by an absorbed power-law with a photon index of 1.99 +/- 0.07. The
best-fitting absorption column is (6.08 +1.04 -0.99) x 10^21 cm^-2, at
a redshift of 1.71 (Xu et al., GCN Circ 10053), in addition to the
Galactic value of 1.4 x 10^20 cm^-2 (Kalberla et al. 2005). The PC
mode spectrum from 436 s to 7.3 ks (with an exposure time of 3.5 ks)
has a photon index of (2.15 +0.12 -0.11) and a best-fitting intrinsic
absorption column of (5.1 +1.6 -1.5) x 10^21 cm^-2. The counts to
observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from
this spectrum is 3.4 x 10^-11 (4.4 x 10^-11) erg cm^-2 count^-1.
If the light curve continues to decay at the same rate, the count rate
at T+24 hours will be 0.015 count s^-1, which corresponds to an
observed (unabsorbed) 0.3-10 keV flux of 4.8 x 10^-13 (6.3 x 10^-13)
erg cm^-2 s^-1.
The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/00373458.
This circular is an official product of the Swift-XRT team.
GCN Circular 10054
Subject
GRB091020 Swift/UVOT observations
Date
2009-10-21T11:18:58Z (16 years ago)
From
Samantha Oates at MSSL <sro@mssl.ucl.ac.uk>
S. R. Oates (MSSL-UCL) and J. L. Racusin (NASA/GSFC/ORAU) report on
behalf of the Swift/UVOT team:
The Swift/UVOT began observerving the field of GRB 091020 89 s
after the BAT trigger (Racusin et al., GCN Circ. 10048). We detect the
optical afterglow in all filters at the refined UVOT position
RA, Dec 175.730, +50.97833, which is
RA (J2000) 11:42:55.20
Dec (J2000) 50:58:42.0
with an estimated uncertainty of 0.5 arcsec (radius, 90% confidence).
This position is consistent with the enhanced XRT position (Beardmore
et al., GCN 10050). The detection in the white, v, b and u filters and
the weak detection in the uvw1 filter is consistent with a redshift
z~1.7, which is consistent with redshift reported by NOT (Xu, et al.,
GCN 10053).
Preliminary magnitudes and 3 sigma upper limits are reported below.
Filter T_start(s) T_stop(s) Exposure(s) Mag Err
------------------------------------------------------------------------
white 89 239 147 15.73 +/- 0.01
white 874 1024 147 17.27 +/- 0.03
v 799 819 19 16.40 +/- 0.15
b 1153 1173 19 17.27 +/- 0.15
u 707 727 19 17.06 +/- 0.16
uvw1 683 6929 490 20.29 +/- 0.35
uvm2 657 6723 490 > 20.29
uvw2 608 6314 303 > 20.27
-------------------------------------------------------------------------
The above magnitudes are not corrected for the Galactic extinction
corresponding to a reddening of E_{B-V} = 0.02 mag (Schlegel et al.,
1998, ApJS, 500, 525). The photometry is on the UVOT photometric system
described in Poole et al. (2008, MNRAS, 383,627).
GCN Circular 10053
Subject
GRB 091020: NOT spectroscopic redshift
Date
2009-10-21T08:24:22Z (16 years ago)
From
Daniele Malesani at Dark Cosmology Centre, Niels Bohr Inst <malesani@astro.ku.dk>
Dong Xu, Johan P.U. Fynbo (DARK/NBI), Nial R. Tanvir (Univ. Leicester),
Jens Hjorth, Giorgos Leloudas, Daniele Malesani (DARK/NBI), Pall
Jakobsson (Univ. Iceland), Paul A. Wilson (NOT and Univ. Oslo), Johannes
Andersen (NBI and NOT), report on behalf of a larger collaboration:
We observed the optical afterglow of GRB 091020 (Racusin et al., GCN
10048; Gorbovskoy et al., GCN 10052) with the Nordic Optical Telescope
equipped with ALFOSC. We detect the afterglow with a magnitude R ~ 20,
based on a nearby USNO star, with mean time Oct 21.220 UT (0.315 days
after the GRB).
We secured low-resolution spectroscopy (30 min exposure), covering the
wavelength range 3500-9100 AA, starting on Oct. 21.231 UT. Wavelength
calibration was carried out using archival frames.
In a preliminary analysis we detect several absorption features, which
we interpret as FeII 2344, 2374, 2382, Al III 1854, 1862, Mg II 2798 (Mg
II 2803 is blended with the telluric A band), all at the common z =
1.71. There is flux in the spectrum down to ~3800 AA, setting a firm
upper limit z < 2.13 to the GRB redshift.
GCN Circular 10052
Subject
GRB 091020: MASTER optical transient polarimetry
Date
2009-10-21T05:15:37Z (16 years ago)
From
Vladimir Lipunov at Moscow State U/Krylov Obs <gcncirc@observ.inetcomm.ru>
E. Gorbovskoy,D.Kuvshinov, V. Lipunov, V.Kornilov, D.Kuvshinov,
A.Belinski, A. Krylov, N.Shatskiy, N.Tyurina, P.Balanutsa, V.V.Chazov,
Sternberg Astronomical Institute, Moscow State University
A. Tlatov, A.V. Parkhomenko, D. Dormidontov
Kislovodsk Solar Station of the Pulkovo Observatory
V.Krushinski, I.Zalognikh, T.Kopytova, A. Popov
Ural State University, Kourovka
S.Yazev, K.Ivanov, N.M.Budnev
Irkutsk State University
V.Yurkov
Blagoveschensk Educational State University, Blagoveschensk
MASTER II robotic telescope (MASTER-Net: http://observ.pereplet.ru, 2x400
mm, 8 square degrees, 2x16Mpx Apogee CCD) located
at Kislovodsk was pointed to the GRB 091020 (Racusin et al., GCN 10048)
by internet 3422 s after the GRB time. The
large delay was caused with technical problems on site.
We see bright optical counterpart (~17.5 mag) on the firrst images at UVOT
position.
We have 130 images with 180 sec synchronous exposition each and 19.5
magnitude limit during ~4 hours in two polarization.
The power low decay with alpha ~= 1.3 during 2.5 hours is observed.
This is the preliminary result.
The reduction is continued.
The message may be cited.
mailto: lipunov@sai.msu.ru
GCN Circular 10051
Subject
GRB 091020, Swift-BAT refined analysis
Date
2009-10-21T01:28:59Z (16 years ago)
From
Hans Krimm at NASA-GSFC <hans.krimm@nasa.gov>
D. M. Palmer (LANL), 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), C. B. Markwardt (GSFC/UMD), A. M. Parsons (GSFC),
J. L. Racusin (NASA/GSFC/ORAU), T. Sakamoto (GSFC/UMBC), G. Sato (ISAS),
M. Stamatikos (GSFC/ORAU), J. Tueller (GSFC), T. N. Ukwatta (GWU)
(i.e. the Swift-BAT team):
Using the data set from T-61 to T+242 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 091020 (trigger #373458)
(Racusin, et al., GCN Circ. 10048). The BAT ground-calculated position is
RA, Dec = 175.727, 50.977 deg which is
RA(J2000) = 11h 42m 54.4s
Dec(J2000) = +50d 58' 36.6"
with an uncertainty of 1.0 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 43%.
The mask-weighted light curve began with a small hump at T-10 sec, rising
sharply to a peak at T+2 sec and decaying exponentially out to T+50 sec,
with a much smaller peak superimposed at T+30 sec. T90 (15-350 keV) is
34.6 +- 2.7 sec (estimated error including systematics).
The time-averaged spectrum from T-8.7 to T+38.3 sec is best fit by a simple
power-law model. The power law index of the time-averaged spectrum is
1.53 +- 0.07. The fluence in the 15-150 keV band is
3.7 +- 0.1 x 10^-6 erg/cm2. The 1-sec peak photon flux measured from
T+1.14 sec in the 15-150 keV band is 4.2 +- 0.3 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/373458/BA/
GCN Circular 10050
Subject
GRB 091020: Enhanced Swift-XRT position
Date
2009-10-21T00:30:43Z (16 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 1088 s of XRT Photon Counting mode data and 1 UVOT
images for GRB 091020, 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 = 175.73005, +50.97839 which is equivalent
to:
RA (J2000): 11h 42m 55.21s
Dec (J2000): +50d 58' 42.2"
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 10048
Subject
GRB 091020: Swift detection of a burst with an optical afterglow
Date
2009-10-20T21:47:36Z (16 years ago)
From
David Palmer at LANL <palmer@lanl.gov>
J. L. Racusin (NASA/GSFC/ORAU), S. D. Barthelmy (GSFC),
A. P. Beardmore (U Leicester), D. N. Burrows (PSU),
J. R. Cummings (NASA/UMBC), N. Gehrels (NASA/GSFC), C. Gronwall (PSU),
S. T. Holland (CRESST/USRA/GSFC), E. A. Hoversten (PSU),
J. A. Kennea (PSU), H. A. Krimm (CRESST/GSFC/USRA),
N. P. M. Kuin (MSSL), W.B Landsman (GSFC), V. Mangano (INAF-IASFPA),
F. E. Marshall (NASA/GSFC), P. T. O'Brien (U Leicester),
K. L. Page (U Leicester), D. M. Palmer (LANL),
P. Romano (INAF-IASFPA), A. Rowlinson (U Leicester),
M. H. Siegel (PSU), E. Troja (NASA/GSFC/ORAU) and
T. N. Ukwatta (GSFC/GWU) report on behalf of the Swift Team:
At 21:36:44 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 091020 (trigger=373458). Swift slewed immediately to the burst.
The BAT on-board calculated location is
RA, Dec 175.715, +50.972 which is
RA(J2000) = 11h 42m 52s
Dec(J2000) = +50d 58' 19"
with an uncertainty of 3 arcmin (radius, 90% containment, including
systematic uncertainty). The BAT light curve showed a bright peak
with a second much smaller peak at T+30 s, for a total duration
of about 45 sec. The peak count rate was ~5000 counts/sec (15-350 keV),
at ~2 sec after the trigger.
The XRT began observing the field at 21:38:05.5 UT, 80.8 seconds after
the BAT trigger. XRT found a bright, fading, uncatalogued X-ray source located
at RA, Dec 175.7284, +50.9788 which is equivalent to:
RA(J2000) = 11h 42m 54.81s
Dec(J2000) = +50d 58' 43.6"
with an uncertainty of 5.0 arcseconds (radius, 90% containment). This
location is 39 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.
The initial flux in the 2.5 s image was 3.01e-09 erg cm^-2 s^-1 (0.2-10
keV).
UVOT took a finding chart exposure of 150 seconds with the White filter
starting 89 seconds after the BAT trigger. There is a candidate afterglow in
the rapidly available 2.7'x2.7' sub-image at
RA(J2000) = 11:42:55.18 = 175.72993
DEC(J2000) = +50:58:41.9 = 50.97831
with a 90%-confidence error radius of about 0.74 arc sec. This position is 3.9
arc sec. from the center of the XRT error circle. The estimated magnitude is
15.73 with a 1-sigma error of about 0.14. No correction has been made for the
expected extinction corresponding to E(B-V) of 0.02.
Burst Advocate for this burst is J. L. Racusin (judith.racusin 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.)