An absolute calibration of DENIS (deep near infrared southern sky survey)

An absolute calibration of the DENIS photometric system is presented. It includes the determination of the overall transmission. profiles in the 3 bands, namely i, J and K(s), combining contributions from atmosphere, telescope mirrors, instrument lenses and dichroics, filters: and detectors. From these normalized profiles, isophotal and effective wavelengths are computed, using the same synthetic Vega spectrum as that used to support the absolute calibration of many other ground-based and spaceborne photometric systems. Flux densities at zero magnitude are derived and integrated to give in-band fluxes, which are used to compute theoretical zero-points and compare them to observed ones, yielding estimates of the overall throughput of the whole system.