101 Virginis

101 Virginis is a red giant variable star in the Boötes constellation. It was originally catalogued as 101 Virginis by Flamsteed due to an error in the position. When it was confirmed as a variable star, it was actually within the border of the constellation Bootes and given the name CY Boötis.

The variability is not strongly defined but a primary period of 23 days and a secondary period of 340 days have been reported.

CY Boo is listed in the Hipparcos catalogue as a "problem binary", a star which was suspected of being multiple but for which the Hipparcos observations did not give a satisfactory solution. Further observations have always shown it to be single.