[vsnet-grb-info 4476] GRB 070406 - SDSS Pre-Burst Observations
GCN Circulars
gcncirc at capella.gsfc.nasa.gov
Sat Apr 7 06:07:29 JST 2007
TITLE: GCN CIRCULAR
NUMBER: 6248
SUBJECT: GRB 070406 - SDSS Pre-Burst Observations
DATE: 07/04/06 21:07:24 GMT
FROM: Richard J. Cool at U.of AZ/Steward Obs <rcool at as.arizona.edu>
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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 GRB070406
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/GRB070406
We supply FITS images in each of the 5 SDSS bands of a 8'x8' region
centered
on the GRB position (ra=198.956 (13:15:49.4), dec=16.5290 (16:31:44.4);
Swift-BAT TRIGGER 274153), 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 GRB070406_sdss.calstar.dat, we report photometry and
astrometry
of 222 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 GRB070406_sdss.objects_flux.dat and
GRB070406_sdss.objects_magnitudes.dat, we report photometry of 1108
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 GRB070406_sdss.objects_flux.dat are in nanomaggies
while the magnitudes listed in GRB070406_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=0.141 mag, A_g=0.103 mag,
A_r =
0.075 mag, A_i=0.057 mag, and A_z=0.040 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, PASP 118, 733).
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.
--Apple-Mail-40-17927870
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<HTML><BODY style=3D"word-wrap: break-word; -khtml-nbsp-mode: space; =
-khtml-line-break: after-white-space; "><DIV>Richard J. Cool (Arizona), =
Daniel J. Eisenstein (Arizona), David W. Hogg</DIV><DIV>(NYU), Michael =
R. Blanton (NYU), David J. Schlegel (LBNL), J. Brinkmann =
(APO),</DIV><DIV>Donald Q. Lamb (Chicago), Donald P. Schneider (PSU), =
and Daniel E. Vanden Berk</DIV><DIV>(PSU) report:</DIV><DIV><BR =
class=3D"khtml-block-placeholder"></DIV><DIV>The Sloan Digital Sky =
Survey (SDSS) imaged the field of burst GRB070406</DIV><DIV>prior to the =
burst.=A0 As these data should be useful as a pre-burst =
comparison</DIV><DIV>and for calibrating photometry, we are supplying =
the images and photometry</DIV><DIV>measurements for this GRB field to =
the community.</DIV><DIV><BR =
class=3D"khtml-block-placeholder"></DIV><DIV>Data from the SDSS, =
including 5 FITS images, 3 JPGS, and</DIV><DIV>3 files of photometry and =
astrometry, are being placed at</DIV><DIV><A =
href=3D"http://mizar.as.arizona.edu/~grb/public/GRB070406">http://mizar.as=
.arizona.edu/~grb/public/GRB070406</A></DIV><DIV><BR =
class=3D"khtml-block-placeholder"></DIV><DIV>We supply FITS images in =
each of the 5 SDSS bands of a 8'x8' region centered</DIV><DIV>on the GRB =
position (ra=3D198.956 (13:15:49.4), dec=3D16.5290 =
(16:31:44.4);</DIV><DIV>Swift-BAT TRIGGER 274153), as well as 3 gri =
color-composite JPGs (with</DIV><DIV>different stretches). The units in =
the FITS images are nanomaggies per pixel.</DIV><DIV>A pixel is 0.396 =
arcsec on a side. A nanomaggie is a flux-density unit equal</DIV><DIV>to =
10^-9 of a magnitude 0 source or, to the extent that SDSS is an AB =
system,</DIV><DIV>3.631e-6 Jy.=A0 The FITS images have WCS astrometric =
information.</DIV><DIV><BR class=3D"khtml-block-placeholder"></DIV><DIV>In=
the file GRB070406_sdss.calstar.dat, we report photometry and =
astrometry</DIV><DIV>of 222 bright stars (r<20.5) within 15' of the =
burst location.=A0 The magnitudes</DIV><DIV>presented in this file are =
asinh magnitudes as are standard in the SDSS (Lupton</DIV><DIV>1999, AJ, =
118, 1406). Beware that some of these stars are not =
well-detected</DIV><DIV>in the u-band; use the errors and object flags =
to monitor data quality.</DIV><DIV><BR =
class=3D"khtml-block-placeholder"></DIV><DIV>In the files =
GRB070406_sdss.objects_flux.dat =
and</DIV><DIV>GRB070406_sdss.objects_magnitudes.dat, we report =
photometry of 1108</DIV><DIV>objects detected within 6' of the GRB =
position.=A0 We have removed saturated</DIV><DIV>objects and objects =
with model magnitudes fainter than 23.0 in the r-band.</DIV><DIV>The =
fluxes listed in GRB070406_sdss.objects_flux.dat are in =
nanomaggies</DIV><DIV>while the magnitudes listed in =
GRB070406_sdss.objects_magnitudes.dat are</DIV><DIV>asinh =
magnitudes.</DIV><DIV><BR class=3D"khtml-block-placeholder"></DIV><DIV>All=
quantities reported are standard SDSS photometry, meaning that they =
are</DIV><DIV>very close to AB zeropoints and magnitudes are quoted in =
asinh magnitudes.</DIV><DIV>Photometric zeropoints are known to about 2% =
rms.=A0 None of the photometry</DIV><DIV>is corrected for dust =
extinction.=A0 The Schlegel, Finkbeiner, and Davis</DIV><DIV>(1998) =
predictions for this region are A_U=3D0.141 mag, A_g=3D0.103 mag, A_r =
=3D</DIV><DIV>0.075 mag, A_i=3D0.057 mag, and A_z=3D0.040 =
mag.</DIV><DIV><BR class=3D"khtml-block-placeholder"></DIV><DIV>There =
are currently no objects within 6 arcminutes of the GRB position =
in</DIV><DIV>the SDSS spectroscopic database.</DIV><DIV><BR =
class=3D"khtml-block-placeholder"></DIV><DIV>SDSS astrometry is =
generally better than 0.1 arcsecond per coordinate.</DIV><DIV>Users =
requiring high precision astrometry should take note that the =
SDSS</DIV><DIV>astrometric system can differ from other systems such as =
those used in other</DIV><DIV>notices; we have not checked the offsets =
in this region.</DIV><DIV><BR =
class=3D"khtml-block-placeholder"></DIV><DIV>More detailed information =
pertaining to our SDSS GRB releases can be found</DIV><DIV>in our =
initial data release paper (Cool et al. 2006, PASP 118, 733).=A0 See =
the</DIV><DIV>SDSS DR4 documentation for more details: <A =
href=3D"http://www.sdss.org/dr5">http://www.sdss.org/dr5</A>.</DIV><DIV><B=
R class=3D"khtml-block-placeholder"></DIV><DIV>These data have been =
reduced using a slightly different pipeline than that</DIV><DIV>used for =
SDSS public data releases.=A0 We cannot guarantee that the values =
here</DIV><DIV>will exactly match those in the data release in which =
these data are included.</DIV><DIV>In particular, we expect the =
photometric calibrations to differ by of order</DIV><DIV>0.01 =
mag.</DIV><DIV><BR class=3D"khtml-block-placeholder"></DIV><DIV>This =
note may be cited, but please also cite the SDSS data release =
paper,</DIV><DIV>Adelman-McCarthy et al. (2006, ApJS, 162, 38), when =
using the data or</DIV><DIV>referring to the technical =
documentation.</DIV><DIV><SPAN class=3D"Apple-style-span" =
style=3D"border-collapse: separate; border-spacing: 0px 0px; color: =
rgb(0, 0, 0); font-family: Helvetica; font-size: 13px; font-style: =
normal; font-variant: normal; font-weight: normal; letter-spacing: =
normal; line-height: normal; text-align: auto; =
-khtml-text-decorations-in-effect: none; text-indent: 0px; =
-apple-text-size-adjust: auto; text-transform: none; orphans: 2; =
white-space: normal; widows: 2; word-spacing: 0px; "><B><BR =
class=3D"Apple-interchange-newline"></B></SPAN> </DIV><BR></BODY></HTML>=
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