Filters that undoubtedly interest advanced libraries of variable star observations. These are Johnson's UBVRI system photometric filters, well-known to professional astronomers and being a standard in modern astrophysics. Each filter passes a band with a specific wavelength, the bandwidth is also standardized. Due to such standardization, photometric results are comparable in various observers, hardware differences resulting from, for example, the characteristics of the CCD converter become irrelevant. Among the advanced astro-amators, photometry using the V-filter is now widespread, data of this type are collected and analyzed, among others, by AAVSO. Photometry of the same object in different filters allows to precisely determine the amount of radiation for specific ranges of wavelength. This allows a unified way to determine the so-called color indicators, which are one of the information needed to determine the temperature, spectral type or stage of the evolutionary star.
Catalog number: 2459440V
• filter V - from the center of the band for green (wavelength ? = 545 nm, FWHM = 66 nm)