A $K_s$-band selected catalogue of objects in the ALHAMBRA survey
  The original ALHAMBRA catalogue contained over 400,000 galaxies selected
using a synthetic F814W image, to the magnitude limit AB(F814W)$\approx$24.5.
Given the photometric redshift depth of the ALHAMBRA multiband data (<z>=0.86)
and the approximately $I$-band selection, there is a noticeable bias against
red objects at moderate redshift. We avoid this bias by creating a new
catalogue selected in the $K_s$ band. This newly obtained catalogue is
certainly shallower in terms of apparent magnitude, but deeper in terms of
redshift, with a significant population of red objects at $z>1$. We select
objects using the $K_s$ band images, which reach an approximate AB magnitude
limit $K_s \approx 22$. We generate masks and derive completeness functions to
characterize the sample. We have tested the quality of the photometry and
photometric redshifts using both internal and external checks. Our final
catalogue includes $\approx 95,000$ sources down to $K_s \approx 22$, with a
significant tail towards high redshift. We have checked that there is a large
sample of objects with spectral energy distributions that correspond to that of
massive, passively evolving galaxies at $z > 1$, reaching as far as $z \approx
2.5$. We have tested the possibility of combining our data with deep infrared
observations at longer wavelengths, particularly Spitzer IRAC data.
