A period-finding method for sparse randomly spaced observations or “How long is a piece of string?”

Abstract

A string-length method for establishing the period of a variable star from a relatively small number of randomly spaced observations over a long span of time is investigated. Criteria for establishing the validity of indicated periods are presented. The method is particularly suited for determination of periods in the limiting case of relatively few observations of reasonably high accuracy. A revised period and orbital elements for a spectroscopic binary observed by Abt & Levy (17 Lyr) are given. The period given by Abt & Levy for 18 Com is not confirmed; the data are insufficient to determine the correct period.