J-PLUS: photometric calibration of large area multi-filter surveys with
  stellar and white dwarf loci
  We present the photometric calibration of the twelve optical passbands
observed by the Javalambre Photometric Local Universe Survey (J-PLUS). The
proposed calibration method has four steps: (i) definition of a high-quality
set of calibration stars using Gaia information and available 3D dust maps;
(ii) anchoring of the J-PLUS gri passbands to the Pan-STARRS photometric
solution, accounting for the variation of the calibration with the position of
the sources on the CCD; (iii) homogenization of the photometry in the other
nine J-PLUS filters using the dust de-reddened instrumental stellar locus in (X
- r) versus (g - i) colours, where X is the filter to calibrate. The zero point
variation along the CCD in these filters was estimated with the distance to the
stellar locus. Finally, (iv) the absolute colour calibration was obtained with
the white dwarf locus. We performed a joint Bayesian modelling of eleven J-PLUS
colour-colour diagrams using the theoretical white dwarf locus as reference.
This provides the needed offsets to transform instrumental magnitudes to
calibrated magnitudes outside the atmosphere. The uncertainty of the J-PLUS
photometric calibration, estimated from duplicated objects observed in adjacent
pointings and accounting for the absolute colour and flux calibration errors,
are ~19 mmag in u, J0378 and J0395, ~11 mmag in J0410 and J0430, and ~8 mmag in
g, J0515, r, J0660, i, J0861, and z. We present an optimized calibration method
for the large area multi-filter J-PLUS project, reaching 1-2% accuracy within
an area of 1 022 square degrees without the need for long observing calibration
campaigns or constant atmospheric monitoring. The proposed method will be
adapted for the photometric calibration of J-PAS, that will observe several
thousand square degrees with 56 narrow optical filters.
