ABSTRACT. We have calculated improved photonic passbands for the UBV RI, Hipparcos H p , and Tycho B T and V T standard systems using the extensive spectrophotometric libraries of NGSL and MILES. Using the H p passband, we adjusted the absolute flux levels of stars in the spectrophotometric libraries so that their synthetic H p magnitudes matched the precise Hipparcos Catalogue value. Synthetic photometry based on the renormalized fluxes was compared with the standard UBV RI, B T and V T magnitudes, and revised synthetic zero points were determined. The Hipparcos and Tycho photometry system zero points were also compared with the V -magnitude zero points of the SAAO UBV RI system, the homogenized UBV system, and the Walraven V B system. The confusion in the literature concerning broadband magnitudes, fluxes, passbands, and the choice of appropriate mean wavelengths is detailed and discussed in the Appendix.

We present the first data release (DR1) of the SkyMapper Southern Survey, a hemispheric survey carried out with the SkyMapper Telescope at Siding Spring Observatory in Australia. Here, we present the survey strategy, data processing, catalogue construction and database schema. The DR1 dataset includes over 66,000 images from the Shallow Survey component, covering an area of 17,200 deg 2 in all six SkyMapper passbands uvgriz, while the full area covered by any passband exceeds 20,000 deg 2 . The catalogues contain over 285 million unique astrophysical objects, complete to roughly 18 mag in all bands. We compare our griz point-source photometry with PanSTARRS1 DR1 and note an RMS scatter of 2%. The internal reproducibility of SkyMapper photometry is on the order of 1%. Astrometric precision is better than 0.2 arcsec based on comparison with Gaia DR1. We describe the end-user database, through which data are presented to the world community, and provide some illustrative science queries.