SIMBAD references

It is shown that the addition to the Stroemgren four-color photometric system of three passbands at 374, 516 and 656 nm from the Vilnius photometric system makes the combined system more universal. This new system, called the Stroemvil system, makes it possible to classify stars of all spectral types, even in the presence of interstellar reddening. This property of the system is especially important in CCD photometry, allowing the photometric classification of very faint stars. A preliminary calibration of the system in terms of spectral and luminosity classes, temperatures and surface gravities is available. A list of preliminary standards for the Stroemvil system in the regions of Cygnus, Aquila and near the North Celestial Pole is given.