A member of a class of pulsating stars with a period of 1 to 35 days located in the instability strip of the H-R diagram. Also known as type II Cepheid variables, W Virginis stars are typically 1.5 ma
g fainter than classical Type I Cepheids and have a mass less than that of the Sun. They also exhibit a period-luminosity relation which is distinct, but works in a similar way to the relation for Type I Cepheids. Hence W Virginis stars can also be used to measure Galactic and extragalactic distances.
Call letters of the radio station over which National Institute of Standards and Technology broadcasts time-standard signals at 2.5, 5, 10, 15, and 20 MHz. Solar-terrestrial conditions and forecasts
are broadcast at 18 minutes past the hour.