All-Sky Spectrally Matched UBVRI - ZY and u‧ g‧ r‧ i‧ z‧ Magnitudes for Stars in the Tycho2 Catalog

We present fitted UBVRI - ZY and u^‧ g^‧ r^‧ i^‧ z^‧ magnitudes, spectral types, and distances for 2.4 million stars, derived from synthetic photometry of a library spectrum that best matches the Tycho2 B_T V_T, NOMAD R_N, and 2MASS JHK_2/S catalog magnitudes. We present similarly synthesized multifilter magnitudes, types, and distances for 4.8 million stars with 2MASS and SDSS photometry to g < 16 within the Sloan survey region, for Landolt and Sloan primary standards, and for Sloan northern (photometric telescope) and southern secondary standards. The synthetic magnitude zero points for B_T V_T, UBVRI, Z_V Y_V, JHK_2/S, JHK_MKO, Stromgren uvby, Sloan u^‧ g^‧ r^‧ i^‧ z^‧, and ugriz are calibrated on 20 CALSPEC spectrophotometric standards. The UBVRI and ugriz zero points have dispersions of 1-3%, for standards covering a range of color from -0.3 < V - I < 4.6 those for other filters are in the range of 2-5%. The spectrally matched fits to Tycho2 stars provide estimated 1σ errors per star of ∼0.2, 0.15, 0.12, 0.10, and 0.08 mag, respectively, in either UBVRI or u^‧ g^‧ r^‧ i^‧ z^‧ those for at least 70% of the SDSS survey region to g < 16 have estimated 1σ errors per star of ∼0.2, 0.06, 0.04, 0.04, and 0.05 in u^‧ g^‧ r^‧ i^‧ z^‧ or UBVRI. The density of Tycho2 stars, averaging about 60 stars per square degree, provides sufficient stars to enable automatic flux calibrations for most digital images with fields of view of 0.5° or more. Using several such standards per field, automatic flux calibration can be achieved to a few percent in any filter, at any air mass, in most workable observing conditions, to facilitate intercomparison of data from different sites, telescopes, and instruments.