A Survey for Infall Motions toward Starless Cores. I. CS (2-1) and N${}_2$H${}^{+}$ (1-0) Observations

In this paper, we present the first results of a survey of 220 starless cores selected primarily by their optical obscuration (Lee & Myers 1999) and observed in CS (2-1), N${}_2$H${}^{+}$ (1-0), and C${}^{18}$O (1-0) using the NEROC Haystack 37-m telescope, to quantify the incidence of infall motions toward starless cores and find infall candidates for further study in the future.