COMMISSION 27 OF THE I. A. U. INFORMATION BULLETIN ON VARIABLE STARS Number 2329 Konkoly Observatory Budapest 6 May 1983 HU ISSN 0374 - 0676 THE PERIOD VARIATIONS OF UX Dra New times of minimum light of the carbon star UX Dra were derived from the three colour photoelectric observations made at Brno Observatory and from the observations made by Dzervitis et al. (1973). They are collected in the following table: -------------------------------------- JD_min (O-C) E Observer -------------------------------------- 2441705: -3.7 0 Dzervitis et al. 2040: 9.0 2 Dzervitis et al. 4331 -2.6 16 Vetesnik 4500 -1.3 17 Vetesnik 4665 2.7 18 Vetesnik 4833 -4.8 19 Vetesnik 5005 -1.7 20 Vetesnik 5179 3.0 21 Vetesnik ------------------------------------- The minima express the effect of the lengthening of the period and can be well represented with the quadratic formula JD_min = 2441708.7+ 160.7d E + 0.21d E^2 . This ephemeris was used for the computation of the (O-C)'s in the table above. Our attention was also directed to consider the behaviour of the light changes of the star in the time of the old photographic observations made by Payne-Gaposhkin (1952). It was found that the period varied almost linearly in two long term cycles in the duration of about 5000 days. The lengthening of the period from 155 to 185 days was interrupted with an abrupt break at the end of each cycle. The breaks during which the period fell down to the minimum value were: JD 241 7400, 242 2000 and 242 8000. The mean period of about 170 days is keeping till this time. M. VETESNIK Department of Astronomy, Brno University 61137 Brno, Czechoslovakia References: Dzervitis, U., Paupers, O., Spulgis, G. 1979, Issl. Solnca i Krasnych Zvezd, Riga, No. 9, 5. [BIBCODE 1979ISKZ....9....5D ] Payne-Gaposhkin, C. 1952, Harvard Ann., 118, 217. [BIBCODE 1952AnHar.118..217P ]