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Session 43 - Variable Stars.
Display session, Thursday, January 08
We present the results of a red photographic photometry of the variable masing star MWC349. Spanning the fourteen years 1967-1981, this photometry was completed using plates from the Damon collection of the Harvard College Observatory. The plates were measured with the iris photometer of the Maria Mitchell Observatory and calibrated with the aid of two standard stars, both brighter than MWC349. The magnitude of MWC349 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. We reveal, for the first time, a periodic component of light variations of this peculiar star. Our preliminary estimate of the period is 9.2 \pm 0.5 years. Extrapolation of this period to earlier and later epochs demonstrates a satisfactory agreement with the available photographic and photoelectric photometry. Possible causes of periodicity are briefly discussed.
Program listing for Thursday