The miniJPAS survey: a preview of the Universe in 56 colours
  The Javalambre-Physics of the Accelerating Universe Astrophysical Survey
(J-PAS) will soon start to scan thousands of square degrees of the northern
extragalactic sky with a unique set of $56$ optical filters from a dedicated
$2.55$m telescope, JST, at the Javalambre Astrophysical Observatory. Before the
arrival of the final instrument (a 1.2 Gpixels, 4.2deg$^2$ field-of-view
camera), the JST was equipped with an interim camera (JPAS-Pathfinder),
composed of one CCD with a 0.3deg$^2$ field-of-view and resolution of 0.23
arcsec pixel$^{-1}$. To demonstrate the scientific potential of J-PAS, with the
JPAS-Pathfinder camera we carried out a survey on the AEGIS field (along the
Extended Groth Strip), dubbed miniJPAS. We observed a total of $\sim 1$
deg$^2$, with the $56$ J-PAS filters, which include $54$ narrow band (NB,
$\rm{FWHM} \sim 145$Angstrom) and two broader filters extending to the UV and
the near-infrared, complemented by the $u,g,r,i$ SDSS broad band (BB) filters.
In this paper we present the miniJPAS data set, the details of the catalogues
and data access, and illustrate the scientific potential of our multi-band
data. The data surpass the target depths originally planned for J-PAS, reaching
$\rm{mag}_{\rm {AB}}$ between $\sim 22$ and $23.5$ for the NB filters and up to
$24$ for the BB filters ($5\sigma$ in a $3$~arcsec aperture). The miniJPAS
primary catalogue contains more than $64,000$ sources extracted in the $r$
detection band with forced photometry in all other bands. We estimate the
catalogue to be complete up to $r=23.6$ for point-like sources and up to
$r=22.7$ for extended sources. Photometric redshifts reach subpercent precision
for all sources up to $r=22.5$, and a precision of $\sim 0.3$% for about half
of the sample. (Abridged)
