GRB 061002

J, K. C. Cannizzo (NASA/UMBC), S. D. Barthelmy (GSFC),
A. P. Beardmore (U Leicester), J. R. Cummings (NASA/UMBC),
S. D. Hunsberger (PSU), F. E. Marshall (NASA/GSFC),
K. M. McLean (LANL/UTD), K. L. Page (U Leicester),
D. M. Palmer (LANL) and M. Stamatikos (NASA/ORAU) report on behalf of
the Swift Team:

At 01:03:29 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 061002 (trigger=231974).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA,Dec 220.346, +48.736 {14h 41m 23s, +48d 44' 11"} (J2000)
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve shows a weak peak with a
duration of about 20 sec.  The peak count rate
was ~500 counts/sec (15-350 keV), at ~5 sec after the trigger. 

The XRT began taking data at 01:05:41 UT, 132 seconds after the BAT
trigger. The XRT on-board centroid algorithm did not find a source in
the image, but ground analysis reveals a faint, probably fading source
at RA, Dec = 14h 41m 23.62s, +48d 44' 23.4" (J2000) with an estimated
uncertainty of 15 arcsec radius (90% containment). This is 14.9
arcsec from the BAT position. 

UVOT took a finding chart exposure of 400 seconds with the V filter
starting 128 seconds after the BAT trigger. No afterglow candidate
has been found in the initial data products. The 2.7'x2.7' sub-image
covers 25% of the BAT error circle and 100% of the XRT error circle. 
The 3-sigma upper limit  is about 19.0 mag. The 8'x8'region
for the list of sources generated on-board covers 100% of the BAT
error circle. No correction has been made for the expected extinction
of about 0.1 magnitudes. 

---APPENDED NEW UVOT PARAGRAPH---

UVOT took a finding chart exposure of 400 seconds with the V filter starting
128 seconds after the BAT trigger. No afterglow candidate has been found in the
initial data products. The 2.7'x2.7' sub-image covers 25% of the BAT error
circle. The typical 3-sigma upper limit has been about 18.5 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 18.0 mag. No
correction has been made for the expected extinction of about 0.1 magnitudes.

J. K. Cannizzo (NASA/UMBC), S. D. Barthelmy (GSFC),
A. P. Beardmore (U Leicester), J. R. Cummings (NASA/UMBC),
S. D. Hunsberger (PSU), F. E. Marshall (NASA/GSFC),
K. M. McLean (LANL/UTD), K. L. Page (U Leicester),
D. M. Palmer (LANL) and M. Stamatikos (NASA/ORAU)
report on behalf of the Swift Team:

This is the corrected circular (no extra UVOT paragraph plus a slight
change to the 3-sigma upper limit: 18.7).

At 01:03:29 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 061002 (trigger=231974).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA,Dec 220.346, +48.736 {14h 41m 23s, +48d 44' 11"} (J2000)
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve shows a weak peak with a
duration of about 20 sec.  The peak count rate
was ~500 counts/sec (15-350 keV), at ~5 sec after the trigger. 

The XRT began taking data at 01:05:41 UT, 132 seconds after the BAT
trigger.  The XRT on-board centroid algorithm did not find a source in
the image, but ground analysis reveals a faint, probably fading source
at RA, Dec = 14h 41m 23.62s, +48d 44' 23.4" (J2000) with an estimated
uncertainty of 15 arcsec radius (90% containment).  This is 14.9
arcsec from the BAT position. 

UVOT took a finding chart exposure of 400 seconds with the V filter
starting 128 seconds after the BAT trigger.  No afterglow candidate
has been found in the initial data products.  The 2.7'x2.7' sub-image
covers 25% of the BAT error circle and 100% of the XRT error circle. 
The 3-sigma upper limit is about 18.7 mag.  The 8'x8' region
for the list of sources generated on-board covers 100% of the BAT
error circle.  No correction has been made for the expected extinction
of about 0.1 magnitudes.

V. Lipunov, V.Kornilov, A.Belinski, N.Shatskiy, E.Gorbovskoy,D.Kuvshinov,
N.Tyurina, P.Gritsyk
Sternberg Astronomical Institute, Moscow Union 'Optic'

I.Golubov
Kislovodsk Solar Station of the Pulkovo observatory

"MASTER Very Wide Filed Camera located at Kislovodsk Solar Station
(http://observ.pereplet.ru, D=70 mm, 400 square degrees) has moved to the
Swift-BAT trigger 231974 and
it has taken a series of 5s exposures starting 97s after the GRB Time
at 01:05:07 UT under good weather condition.

The limiting magnitude is 12.0m (unfiltered) for single exposures
and 13.0m for the sum of 20 images.

Sum of 10 images: http://pereplet.sai.msu.ru/nauka/spy_sum10.jpg

Reduction in contining.

The message may be cited.

mailto: lipunov@sai.msu.ru

D. Hullinger (BYU-Idaho), L. Barbier (GSFC), S. D. Barthelmy (GSFC),
J. K. Cannizzo (NASA/UMBC), J. Cummings (GSFC/UMBC), E. Fenimore (LANL),
N. Gehrels (GSFC), 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-239 to T+303 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 061002 (trigger #231974)
(Cannizzo, et al., GCN Circ. 5676
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 ).  The BAT ground-calculated position
is RA,Dec = 220.356, 48.726 deg {14h 41m 25.4s, 48d 43' 32.0"} (J2000)
+- 1.7 arcmin, (radius, sys+stat, 90% containment).  The partial coding was 39%.
 
The mask-weighted lightcurve has a single roughly triangular shaped peak
starting at T-10 sec, peaking at T+10 sec, and ending at T+60 sec.  There is
one caveate to this in that there is a 20-sec gap in the downliked data
starting at T+160 sec.  T90 (15-350 keV) is 17.6 +- 1 sec (estimated error
including systematics).
 
The time-averaged spectrum from T-2.3 to T+16.9 is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
1.76 +- 0.21.  The fluence in the 15-150 keV band is 6.8 +- 0.8 x 10^-7 erg/cm2.
The 1-sec peak photon flux measured from T-1.38 sec in the 15-150 keV band
is 0.8 +- 0.3 ph/cm2/sec.  All the quoted errors are at the 90% confidence level.

Richard J. Cool (Arizona), Daniel J. Eisenstein (Arizona),
David W. Hogg (NYU), Michael R. Blanton (NYU), David
J. Schlegel (LBNL), J. Brinkmann (APO), Donald Q. Lamb
(Chicago), Donald P. Schneider (PSU), and Daniel E. Vanden
Berk (PSU) report:

The Sloan Digital Sky Survey (SDSS) imaged the field of
burst GRB061002 prior to the burst.  As these data should
be useful as a pre-burst comparison and for calibrating
photometry, we are supplying the images and photometry
measurements for this GRB field to the community.

Data from the SDSS, including 5 FITS images, 3 JPGS, and
3 files of photometry and astrometry, are being placed
at http://mizar.as.arizona.edu/~grb/public/GRB061002

We supply FITS images in each of the 5 SDSS bands of a
8'x8' region centered on the GRB position (ra=220.346
(14:41:23.0), dec=48.7360 (48:44:09.6); BAT Trigger
231974), as well as 3 gri color-composite JPGs (with
different stretches). The units in the FITS images are
nanomaggies per pixel.  A pixel is 0.396 arcsec on a
side. A nanomaggie is a flux-density unit equal to 10^-9
of a magnitude 0 source or, to the extent that SDSS is
an AB system, 3.631e-6 Jy.  The FITS images have WCS
astrometric information.

In the file GRB061002_sdss.calstar.dat, we report
photometry and astrometry of 226 bright stars (r<20.5)
within 15' of the burst location.  The magnitudes presented
in this file are asinh magnitudes as are standard in the
SDSS (Lupton 1999, AJ, 118, 1406). Beware that some of
these stars are not well-detected in the u-band; use the
errors and object flags to monitor data quality.

In the files GRB061002_sdss.objects_flux.dat and
GRB061002_sdss.objects_magnitudes.dat, we report photometry
of 371 objects detected within 6' of the GRB position.
We have removed saturated objects and objects with
model magnitudes fainter than 23.0 in the r-band.
The fluxes listed in GRB061002_sdss.objects_flux.dat
are in nanomaggies while the magnitudes listed in
GRB061002_sdss.objects_magnitudes.dat are asinh magnitudes.



All quantities reported are standard SDSS photometry,
meaning that they are very close to AB zeropoints
and magnitudes are quoted in asinh magnitudes.
Photometric zeropoints are known to about 2% rms.
None of the photometry is corrected for dust extinction.
The Schlegel, Finkbeiner, and Davis (1998) predictions
for this region are A_U=0.223 mag, A_g=0.164 mag, A_r =
0.119 mag, A_i=0.090 mag, and A_z=0.064 mag.

There are currently no objects within 6 arcminutes of the
GRB position in the SDSS spectroscopic database.


SDSS astrometry is generally better than 0.1 arcsecond
per coordinate.  Users requiring high precision astrometry
should take note that the SDSS astrometric system can
differ from other systems such as those used in other
notices; we have not checked the offsets in this region.

More detailed information pertaining to our SDSS GRB
releases can be found in our initial data release paper
(Cool et al. 2006, astro-ph/0601218).  See the SDSS DR4
documentation for more details: http://www.sdss.org/dr5.

These data have been reduced using a slightly different
pipeline than that used for SDSS public data releases.
We cannot guarantee that the values here will exactly match
those in the data release in which these data are included.
In particular, we expect the photometric calibrations to
differ by of order 0.01 mag.

This note may be cited, but please also cite the SDSS data
release paper, Adelman-McCarthy et al. (2006, ApJS, 162,
38), when using the data or referring to the technical
documentation.

K.L. Page (U. Leicester) and J.K. Cannizzo (NASA/UMBC) report on behalf of 
the Swift-XRT team:

We have analysed the first 3 orbits of GRB 061002 data obtained by the
Swift-XRT. Using the 4.5 ks of Photon Counting data from the second and
third orbits (the first orbit of data was entirely in Windowed Timing
mode), we find a refined position of:

RA(J2000)  =  14 41 23.29
Dec(J2000) = +48 44 30.5

with an estimated uncertainty of 7.5 arcsec (90% confidence, including 
boresight uncertainties). This lies 7.8 arcsec from the initial XRT 
position given by Cannizzo et al. in GCN Circ. 5675
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 , and 60
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 .7 arcsec from 
the ground-calculated BAT position (GCN Circ. 5678
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 ; Hullinger et al.)

The X-ray light-curve shows a break from a steep decay slope of alpha_1 =
2.97 +/- 0.31 to alpha_2 = 1.25 +/- 0.12 at about 304 seconds after the
trigger.

The Windowed Timing spectrum can be modelled by a power-law with a column 
density in excess of the Galactic value in that direction. The fit 
parameters are: Gamma = 2.19 +0.36/-0.31 and NH_excess = (1.5 
+0.8/-0.7)e21 cm^-2 (in addition to NH_Galactic = 2.07e20 cm^-2). The mean 
observed (unabsorbed) flux over this first orbit (138-1345s after the 
burst) was found to be 1.24e-11 (1.90e-11) erg cm^-2 s^-1.

If the decay continues at a rate of alpha = 1.25, the estimated count rate
at 24 hours will be 4.1e-4 count s^-1, corresponding to an observed
(unabsorbed) flux of 1.86e-14 (2.79e-14) erg cm^-2 s^-1.

This circular is an official product of the Swift-XRT team.

A. Breeveld (MSSL/UCL) and J. Cannizzo (NASA/UMBC) report on behalf of
the Swift/UVOT team:

The Swift/UVOT began taking data on 2006-10-02, 129s after the burst
(Cannizzo et al., GCN 5676
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 ), discounting the 10s settling image. At the
position of the XRT error circle (Page et al., GCN 5681
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 ) there are no
new sources. In the summed UVOT images we obtain the following 3 sigma
upper limits:

  Filter    T_range(s)   Exp(s)    3-sig UL (mag)
       v     129-7107    1283      20.32
       b     607-6697    412       20.63
       u     582-12911   1095      20.87
      w1     559-12244   1337      21.11
      m2     534-11337   1354      21.41
      w2     622-6902    432       21.19

These magnitudes are not corrected for the expected extinction of
E(B-V)=0.046