The Alhambra Survey: a Large Area Multimedium-Band Optical and Near-Infrared Photometric Survey
Moles, M.; Benítez, N.; Aguerri, J. A. L.;Alfaro, E. J.; Broadhurst, T.; Cabrera-Caño, J.;Castander, F. J.; Cepa, J.; Cerviño, M.;Cristóbal-Hornillos, D.; Fernández-Soto, A.;González Delgado, R. M.; Infante, L.; Márquez, I.;Martínez, V. J.; Masegosa, J.; del Olmo, A.;Perea, J.; Prada, F.; Quintana, J. M.;Sánchez, S. F.. The Alhambra Survey: a Large Area Multimedium-Band Optical and Near-Infrared Photometric Survey. The Astronomical Journal. 2008, Vol. Volume 136, Issue 3, pp. 1325-1339 (2008)., p. -2008.
Here we describe the first results of the Advanced Large Homogeneous
Area Medium-Band Redshift Astronomical (ALHAMBRA) survey, which provides
cosmic tomography of the evolution of the contents of the universe over
most of cosmic history. Our novel approach employs 20 contiguous,
equal-width, medium-band filters covering from 3500 Å to 9700
Å, plus the standard JHK<SUB>s</SUB> near-infrared (NIR) bands, to
observe a total area of 4 deg<SUP>2</SUP> on the sky. The optical
photometric system has been designed to maximize the number of objects
with accurate classification by spectral energy distribution type and
redshift, and to be sensitive to relatively faint emission features in
the spectrum. The observations are being carried out with the Calar Alto
3.5 m telescope using the wide-field cameras in the optical, Large Area
Imager for Calar Alto, and in the NIR, Omega-2000. The first data
confirm that we are reaching the expected magnitude limits (for a total
of 100 ks integration time per pointing) of AB <= 25 mag (for an
unresolved object, signal-to-noise ratio = 5) in the optical filters
from the blue to 8300 Å, and from AB = 24.7 to 23.4 for the redder
ones. The limit in the NIR, for a total of 15 ks exposure time per
pointing, is (in the Vega system) K<SUB>s</SUB> ≈ 20 mag, H≈ 21
mag, J≈ 22 mag. Some preliminary results are presented here to
illustrate the capabilities of the ongoing survey. We expect to obtain
accurate redshift values, Δz/(1 + z) <= 0.03 for about five
×10<SUP>5</SUP> galaxies with I <= 25 (60% completeness level),
and z <SUB>med</SUB> = 0.74. This accuracy, together with the
homogeneity of the selection function, will allow for the study of the
redshift evolution of the large-scale structure, the galaxy population
and its evolution with redshift, the identification of clusters of
galaxies, and many other studies, without the need for any further
follow-up. It will also provide targets for detailed studies with 10 m
class telescopes. Given its area, spectral coverage, and its depth,
apart from those main goals, the ALHAMBRA survey will also produce
valuable data for galactic studies.
Based on observations collected at the German-Spanish Astronomical
Center, Calar Alto, jointly operated by the Max-Planck-Institut für
Astronomie Heidelberg and the Instituto de Astrofísica de
Andalucía (CSIC).
Here we describe the first results of the Advanced Large Homogeneous
Area Medium-Band Redshift Astronomical (ALHAMBRA) survey, which provides
cosmic tomography of the evolution of the contents of the universe over
most of cosmic history. Our novel approach employs 20 contiguous,
equal-width, medium-band filters covering from 3500 Å to 9700
Å, plus the standard JHK<SUB>s</SUB> near-infrared (NIR) bands, to
observe a total area of 4 deg<SUP>2</SUP> on the sky. The optical
photometric system has been designed to maximize the number of objects
with accurate classification by spectral energy distribution type and
redshift, and to be sensitive to relatively faint emission features in
the spectrum. The observations are being carried out with the Calar Alto
3.5 m telescope using the wide-field cameras in the optical, Large Area
Imager for Calar Alto, and in the NIR, Omega-2000. The first data
confirm that we are reaching the expected magnitude limits (for a total
of 100 ks integration time per pointing) of AB <= 25 mag (for an
unresolved object, signal-to-noise ratio = 5) in the optical filters
from the blue to 8300 Å, and from AB = 24.7 to 23.4 for the redder
ones. The limit in the NIR, for a total of 15 ks exposure time per
pointing, is (in the Vega system) K<SUB>s</SUB> ≈ 20 mag, H≈ 21
mag, J≈ 22 mag. Some preliminary results are presented here to
illustrate the capabilities of the ongoing survey. We expect to obtain
accurate redshift values, Δz/(1 + z) <= 0.03 for about five
×10<SUP>5</SUP> galaxies with I <= 25 (60% completeness level),
and z <SUB>med</SUB> = 0.74. This accuracy, together with the
homogeneity of the selection function, will allow for the study of the
redshift evolution of the large-scale structure, the galaxy population
and its evolution with redshift, the identification of clusters of
galaxies, and many other studies, without the need for any further
follow-up. It will also provide targets for detailed studies with 10 m
class telescopes. Given its area, spectral coverage, and its depth,
apart from those main goals, the ALHAMBRA survey will also produce
valuable data for galactic studies.
Based on observations collected at the German-Spanish Astronomical
Center, Calar Alto, jointly operated by the Max-Planck-Institut für
Astronomie Heidelberg and the Instituto de Astrofísica de
Andalucía (CSIC).