APPLICATION OF SYNTHETIC SPECTRA TO COLOR SYSTEM TRANSFORMATIONS .2. PHOTOGRAPHIC AND PHOTOELECTRIC UBV SYSTEMS

Synthetic spectra and the photoelectric and various photographic UBV sensitivity functions are used to compute theoretical colours for F and G dwarfs. Similar calculations are made for hotter stars. It is shown that photographic V magnitudes obtained using 103a-G emulsion and a GG 11 filter will be in better agreement with photoelectric V magnitudes than is the case when the I03a-D emulsion is used. The photographic and photoelectric U and B magnitudes are in good agreement. It is also shown that the use of S20 photocathodes for direct photography with image tubes will introduce large colour corrections terms if V magnitudes are to be measured, unless a BGI8 filter is used in addition to the GG I I filter. © Royal Astronomical Society • Provided by the NASA Astrophysics Data System.