The UKIRT Infrared Deep Sky Survey ZY JHK photometric system: passbands and synthetic colours

The United Kingdom Infrared Telescope (UKIRT) Infrared Deep Sky Survey is a set of five surveys of complementary combinations of area, depth and Galactic latitude, which began in 2005 May. The surveys use the UKIRT Wide Field Camera (WFCAM), which has a solid angle of 0.21 deg2. Here, we introduce and characterize the ZY JHK photometric system of the camera, which covers the wavelength range 0.83-2.37 μm. We synthesize response functions for the five passbands, and compute colours in the WFCAM, Sloan Digital Sky Survey (SDSS) and two-Micron All Sky Survey (2MASS) bands, for brown dwarfs, stars, galaxies and quasars of different types. We provide a recipe for others to compute colours from their own spectra.…