Ca-, b-, and y-band Combined images for Draco, Sextans, and Canes Venatici I
We provide Ca-, b-, and y-band combined images for Draco, Sextans, and Canes Venatici I.
The combined images are created as follows:
the raw data were pre-processed by sdfred1 and sdfred2,
a semi-automated pipeline software for Suprime-Cam (Yagi et al. 2002; Ouchi et al. 2004).
All images were bias-subtracted, trimmed, flat-fielded in the same manner as single chip reduction.
The master flat frames for each filter were obtained from the median combination of the object images.
The distortion by a fast focus (f/2.0) was corrected with 4th order polynomial fitting.
The point-spread-function (PSF) size of all frames was equalized to have a common full
with half maximum value through Gaussian smoothing before coadding.
The interpolated sky counts of 12".8 X 12".8 meshes were used to subtract sky background.
While the frames were combining, the relative position and throughputs among frames were adjusted using the calculation from the common stars. We then obtained combined images for each filter.
The combined images are compressed in gzip format and can be downloaded from the following links.
Draco
Sextans
Canes Venatici I
Photomety data of Draco, Sextans, and Canes Venatici I (in ASCII format)
We provide the photometric measurements of point sources in Draco, Sextans, and Canes Venatici I,
which were obtained as follows:
we detected point sources from the combined images using DAOPHOT/ALLSTAR (Stetson 1987)
to make an input star list for ALLFRAME (Stetson 1994). The PSF models were constructed
for all individual images by DAOPHOT using the best matched analytic approximation.
Due to the large field of view, the PSF models varies quadratically in the frames.
We performed PSF photometry for all individual images simultaneously using ALLFRAME.
Then, the point sources were matched up by DAOMATCH/DAOMASTER (Stetson 1993) and
the aperture corrections were applied using DAOGROW (Stetson 1990). The instrumental
Ca, b, and y magnitudes were converted to the standard Ca-by magnitude system (Anthony-Twarog et al. 1991)
The astrometric standard stars in the USNO B1 catalog were used to compute the
astrometric solutions (Monet et al. 2003). The typical r.m.s. of the astrometric solutions
is at the level of 0."2. Galactic extinction for each star in the three dSphs was corrected
based on the dust map from Schlafly & Finkbeiner (2011) and the extinction law provided
by Cardelli et al. (1989).
Followings contain coordinates, magnitudes and errors, and CHI/SHARP parameters of points sources in the respective galaxies.
Draco
Sextans
Canes Venatici I