Red light curve of MWC 349 in the years 1967-1981: Possible periodicity

The results of a red photographic photometry of the variable masing star MWC 349 are presented for 14 years, 1967-1981. Fourteen plates from the Harvard Damon collection were selected for the photometry. The plates were measured with the Cuffey iris photometer of the Maria Mitchell Observatory and were calibrated with the aid of two standard stars, both brighter than MWC 349. The magnitude of MWC 349 was then determined by extrapolation, assuming that the star is on the linear part of the calibration curve. In spite of larger errors, our results are in good agreement with one photoelectric observation made during the period covered. The obtained red light curve is indicative of periodic light variations. A combined Fourier-least-squares analysis gives a probable period of T = 9.1 +/- 0.3 yr. The deduced period and phase of variations are not incompatible with the subsequent photoelectric photometry of Bergner et al. Possible mechanisms responsible for the periodic light variations are briefly discussed.