GRB 060510A, GRB 060510

GRB 060510A: Swift/UVOT Detection of an Optical Afterglow

S. T. Holland (NASA/GSFC & USRA) reports on behalf of the Swift/UVOT
team:

      The Swift UVOT began observing GRB 060510A (trigger #209351,
Krimm et al., GCN Circular 5095
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 ) 82 seconds after the BAT trigger.  We
detect the UVOT optical transient reported in the above Circular in
the White, V-, and U-band filters.  The J2000 coordinates of the
afterglow are

RA =  06:23:27.98
Dec = -01:09:46.2

with an uncertainty of +/- 0.56 arcseconds (90% containment).

Magnitudes and 3-sigma upper limits are reported below.

          Midpoint   Coadded                Upper
Filter     Time     Exposure   Mag  Err    Limit
           (sec)      (sec)               (3 sigma)
V           405        394    18.38 0.13
V          1060        394    18.85 0.16
B           688         10                  18.4
B          1503         20                  19.2
U           817         20    18.06 0.40
U          1479         20                  18.3
UVW1        645         20                  17.1
UVW1        793         20                  17.4
UVM2        769         20                  17.5
UVM2       1431         20                  17.6
UVW2        721         20                  17.6
UVM2       1384         20                  17.7
White       150         99    18.04 0.15
White       702         10    18.24 0.50
White      1318         99    18.87 0.18
White      1521         10    18.12 0.40
White      1680         10                  18.7

No correction has been made for the Galactic reddening of E(B-V) =
0.42 mag (Schlegel et al. 1998) along the line of sight to GRB
060510A.

S. Golenetskii, R.Aptekar, E. Mazets, V. Pal'shin, D. Frederiks, and
T. Cline on behalf of the Konus-Wind team report:

The long GRB 060510A (Swift-BAT trigger #209351;
Krimm et al., GCN 5095
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 ; Barbier et al., GCN 5108
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 )
triggered Konus-Wind at 27796.301 s UT (07:43:16.301).

As observed by Konus-Wind it had a duration of ~25 s,
fluence 2.55(-0.22,+0.07)x10^-5 erg/cm2,
and the 64-ms peak flux measured from T0+7.488 s
4.29(-0.72, +0.63)x10^-6  erg/cm2/s
(both in the 20 keV - 1 MeV energy range).
The burst shows a strong hard-to-soft spectral evolution.

Fitting the time-integrated spectrum of the burst
(from T0 to T0+24.064 s; in the 20 keV - 1 MeV range)
by a power law with exponential cutoff model:
dN/dE ~ E^(-alpha)*exp(-E*(2-alpha)/Ep)
yields alpha = 1.661(-0.076, +0.072)
and Ep = 184 (-24, +36) keV (chi2 = 63/48 dof).

All the quoted errors are at the 90% confidence level.

The K-W light curve is available at
  http://www.ioffe.rssi.ru/LEA/GRBs/GRB060510_T27796/

L. Barbier (GSFC), S. Barthelmy (GSFC), J. Cummings (GSFC/ORAU),
E. Fenimore (LANL), N. Gehrels (GSFC), D. Hullinger (BYU-Idaho),
H. Krimm (GSFC/USRA), M. Koss (UMD), C. Markwardt (GSFC/UMD), 
D. Palmer (LANL), A. Parsons (GSFC), T. Sakamoto (GSFC/ORAU),
G. Sato (GSFC/JSPS/USRA), M. Stamatikos (GSFC/ORAU), J. Tueller (GSFC)
on behalf of 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 060510A (trigger #209351)
(Krimm, et al., GCN 5095
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 ).  The BAT ground-calculated position is RA,Dec =
95.855, -1.166 deg {6h 23m 25.1s, -1d 9' 56.5"} (J2000) +- 1.2 arcmin,
(radius, sys+stat, 90% containment).  The partial coding was 6%.
 
The mask-weighted lightcurves shows several overlapping peaks
starting at T-8 sec amd ;lasting out to T+25 sec.
T90 (15-350 keV) is 21 +- 3 sec (estimated error including systematics).
 
The time-averaged spectrum from T-7.0 to T+17.1 is best fit by 
a simple power-law model.  The power law index of the time-averaged spectrum
is 1.55 +- 0.10.  The fluence in the 15-150 keV band is
9.8 +- 0.5 x 10^-6 erg/cm2.  The 1-sec peak photon flux measured
from T+0.29 sec in the 15-150 keV band is 17.0 +- 1.9 ph/cm2/sec.
All the quoted errors are at the 90% confidence level.   Because
this burst occured at the edge of the BAT FOV (note the low partial
coding percentage), the spectral fit values have an extra systematic error
contribution of about 10%.

M.L. Conciatore, M. Capalbi, M. Perri, L. Vetere (ASDC), H. A. Krimm
(GSFC/USRA)D. Burrows (PSU) report on behalf of the Swift/XRT team:


We have analysed the first orbit of XRT data from GRB 060510A.
A 1.8ks Photon Counting (PC) mode image provides a refined XRT position:

RA(J2000) =  06 23 28.0
Dec(J2000)=  -01 09 44.2

with an uncertainty of 3.5 arcsec (90% containment).
This position is 1.3 arcsec away from the ground-calculated XRT position 
quoted in Krimm et al. (GCN 5095
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 ), 15.2 arcseconds from the BAT position
(GCN 5095
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 ) and it is consistent with the UVOT position given in GCN 5095
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 .

A power-law fit of the PC spectrum with a column density fixed to the
Galactic one (4.1 e21 cm^-2) gives a photon index of 2.1+/-0.5.
The 0.2-10.0 keV observed flux is 2.0E-10 erg cm^-2 s^-1, which
corresponds to an unabsorbed flux of 3.2E-10 erg cm^-2 s^-1.

The light curve shows a fast initial decay, followed by a flattening
phase. At about 1.2 ks from the trigger, it starts to decay again.

Further osbervations are ongoing.

This circular is an official product of the Swift XRT Team.

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 GRB060510 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/GRB060510

We supply FITS images in each of the 5 SDSS bands of a
8'x8' region centered on the GRB position (ra=95.8671
(06:23:28.1), dec=-1.16247 (-01:09:44.9); GCN 5095
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 ),
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 GRB060510_sdss.calstar.dat, we report
photometry and astrometry of 1819 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 GRB060510_sdss.objects_flux.dat and
GRB060510_sdss.objects_magnitudes.dat, we report photometry
of 2209 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 GRB060510_sdss.objects_flux.dat
are in nanomaggies while the magnitudes listed in
GRB060510_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=2.083 mag, A_g=1.533 mag, A_r =
1.112 mag, A_i=0.843 mag, and A_z=0.598 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/dr4.

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, in
press, astro-ph/0507711), when using the data or referring
to the technical documentation.

H. A. Krimm (GSFC/USRA), S. D. Barthelmy (GSFC),
A. P. Beardmore (U Leicester), D. N. Burrows (PSU),
M. Capalbi (ASDC), M.L. Conciatore (ASDC), N. Gehrels (NASA/GSFC),
C. Gronwall (PSU), S. T. Holland (GSFC/USRA),
K. L. Page (U Leicester), D. M. Palmer (LANL), M. Perri (ASDC),
E. Troja (INAF-IASFPA) and L. Vetere (ASDC) report on behalf of the
Swift Team:

At 07:43:27 UT, Swift-BAT triggered and located GRB 060510 (trigger=209351). 
The spacecraft slewed immediately.  The BAT on-board calculated location
is RA,Dec 95.870d,-1.162d {06h 23m 29s,-1d 09' 43"} (J2000), with an
uncertainty of 3 arcmin (radius, 90% containment, stat+sys). 
The BAT light curve shows a multi-peak structure with a total duration
of ~30 sec.  The peak count rate was ~8000 counts/sec (15-350 keV),
at ~1 seconds after the trigger. 

The XRT began observing the field at 07:44:57 UT, 90 seconds after the
BAT trigger. The on-board centroiding algorithm was confused by a cosmic ray 
close to the X-ray afterglow and the position sent out in the automated GCN 
Notice was incorrect.  Using ground-processed data, we find a bright X-ray source
located at RA(J2000) = 06h 23m 28.1s, Dec(J2000) = -01d 09' 44.9", with an
estimated uncertainty of 8 arcseconds (90% confidence radius). 
This location is 11 arcseconds from the BAT on-board position, within
the BAT error circle. 

UVOT took a finding chart exposure of 100 seconds with the White
(160-650 nm) filter starting 100 seconds after the BAT trigger. 
A fading source was found at RA,Dec = 06h 23m 28.0s -1d 09' 46" (J2000)
with a mag of 18.2.  There is nothing in DSS.  No correction has been made
for the expected extinction corresponding to E(B-V) of 0.41. 

This burst (trigger 209351) should not be confused with the second
Swift-BAT trigger (209352) 38 minutes later.