uvby system

uvby system

(yoo-vee-bee-wÿ ) A system of photometry, devised by B. Strömgren, in which photoelectric magnitudes u , v , b , and y are measured at four wavelength bands: measurements of u (ultraviolet) are centered on 350 nm, v (violet) on 410 nm, b (blue) on 470 nm, and y (yellow) on 550 nm. The bandwidth (20–30 nm) is much narrower than for the UBV system. The uvby system can be used to measure metallicity, temperature, and Balmer discontinuity of A, B, and F stars.

uvby system

[′yüv·bē ‚sis·təm]
(astronomy)
A four-color stellar magnitude system based on measurements in the ultraviolet, violet, blue, and yellow regions. Also known as Strömgren four-color index.