Galaxy And Mass Assembly (GAMA):
The input catalogue and star-galaxy separation
Baldry et al. 2010, published in MNRAS, Vol. 404, pp. 86-100 (link:
ADS).
Abstract
We describe the spectroscopic target selection for the Galaxy And Mass
Assembly (GAMA) survey. The input catalogue is drawn from the Sloan Digital
Sky Survey (SDSS) and UKIRT Infrared Deep Sky Survey (UKIDSS). The aim is to
measure redshifts for galaxies in three 4x12 degree regions at 9h, 12h and
14.5h, on the celestial equator, with magnitude selections r < 19.4, z < 18.2
and K(AB) < 17.6 over all three regions, and r < 19.8 in the 12-h region. The
target density is 1080 per sq. deg. in the 12-h region and 720 per sq. deg. in
the other regions. The average GAMA target density and area are compared with
completed and ongoing galaxy redshift surveys. The GAMA survey implements a
highly complete star-galaxy separation that jointly uses an intensity-profile
separator (delta(sg) = r-band psf mag - model mag) as per the SDSS) and a
colour separator. The colour separator is defined as delta(sg,jk) = J - K -
f(g-i), where f(g-i) is a quadratic fit to the J-K colour of the stellar locus
over the range 0.3 < g-i < 2.3. All galaxy populations investigated are well
separated with delta(sg,jk) > 0.2. From two years out of a three-year AAOmega
program on the Anglo-Australian Telescope, we have obtained 79599 unique
galaxy redshifts. Previously known redshifts in the GAMA region bring the
total up to 98497. The median galaxy redshift is 0.2 with 99% at z < 0.5. We
present some of the global statistical properties of the survey, including
K-band galaxy counts, colour-redshift relations and preliminary n(z).
Data:
K-band galaxy counts as per Figure 4.
n(z) histograms as per Figure 14.
The latest GAMA data release
(GAMA web site).
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