Vilnius Photometric System (Paperback)

Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. The Vilnius photometric system is a medium-band seven-colour photometric system (UPXYZVS), created in 1963 by Vytautas Strai ys and his coworkers. This system was highly optimized for classification of stars from ground based observations. The system was chosen to be medium-band, to ensure the possibility to measure faint stars. The temperature classification of early-type stars is based on Balmer jump (Balmer discontinuity). To measure it one must have two bandpasses placed in the ultraviolet, one beyond the Balmer jump (U magnitude) and another after the jump (X magnitude). The Y bandpass is near the breakpoint of the interstellar extinction law (interstellar extinction in the 300-800 nm region can be approximated by two straight lines, which intersect at 435.5 nm).