2001PASP..113..715T

CCD V-band observations and archival O-C estimates are presented for the 4.237 day Cepheid V1726 Cyg, which is a member of the open cluster C2128+488 (Anon. Platais), and the data are analyzed in conjunction with other available photometric data in order to study the star's period variations. An O-C analysis of the data yields the following improved ephemeris for the variable, HJD_max=2,444,020.5892+4.2369334E+2.044x10^–8E², which implies that the period of V1726 Cyg is increasing at a rate of +0.304±0.026 s.yr^–1, consistent with a star in the third crossing of the instability strip provided that it is pulsating in the first-overtone, rather than fundamental, mode. Overtone pulsation for V1726 Cyg is also indicated by its low amplitude, sinusoidal light curve, and derived Fourier parameters, despite reservations about the significance of the latter. No evidence is found for random cycle-to-cycle variations in period for V1726 Cyg.