COMMISSION 27 OF THE I. A. U. INFORMATION BULLETIN ON VARIABLE STARS Number 1092 Konkoly Observatory Budapest 1976 February 3 Veroffentlichung der Remeis-Sternwarte Bamberg Astronomisches Institut der Universitat Erlangen-Nurnberg Vol. X, No. 117, 1976 PERIOD AND PERIOD CHANGE OF THE ECLIPSING BINARY BV 549 SCORPII The variability of HV 549=CoD -34d12293(9.0m)=HD 163302 (A0) was discovered by Strohmeier, Knigge and Ott (1964). Later Bauernfeind (1968) determined its period from Harvard and Bamberg sky patrol plates to P=1.d888 and derived a nearly sinusoidal curve for the O-C values as function of time with an amplitude of about 0.8 days, indicating a pronounced change of period. With a larger number of plates taken at Boyden Observatory, South Africa, and Mount John Observatory, New Zealand, as well as photoelectric observations made in April and May 1975 with the ESO 50 cm photometric telescope in La Silla, Chile, the following elements could be derived: Minimum = JD 241 4862.585 + 3.776277d E +-0.012 +-0.000003 (m.e.). The Table gives the Julian Date (JD) of the observed minima, the weight (G) of the observations, epoch (E), and the difference O-C between observed and calculated time of minimum in days. The last two points have been determined from photoelectric measurements; in both cases only opposite halves of the minimum have been covered. In the Figure the O-C values are given as function of Julian Date; their mean dispersion is about +-0.06d. The size of the dots is a measure of the weight (scale 1 to 4) of the observed minima. The two solid lines indicate the time intervals covered by the Harvard and Bamberg plate collections. Between JD 242 2500 and 243 3000 no minima could be detected. The sine-shaped course found by Bauernfeind (1968) could not be confirmed. His period was incorrect by half a cycle of the period 3.776d in about 25000 days. BV 549 Sco = CoD-34d12293 (9.0m) = HD 163302 (A0) Min = JD 241 4862.585 + 3.776277d E +-.012 +-.000003 (m.e.) MINIMA --------------------------------------------------------------------- JD G E O-C JD G E O-C --------------------------------------------------------------------- 2414862.622 3 .0 .037 2421427.627 1 1738.5 -.016 14898.571 2 9.5 .111 21867.503 1 1855.0 -.075 15198.671 3 89.0 -.003 38228.365 2 6187.5 .067 15872.810 1 267.5 .070 38264.224 2 6197.0 .051 15925.704 3 281.5 .098 38528.513 2 6267.0 .000 15940.646 3 285.5 -.065 38530.513 2 6267.5 .112 16010.569 2 304.0 -.004 38583.381 2 6281.5 .112 16208.776 4 356.5 -.052 38636.219 3 6295.5 .082 16582.724 4 455.5 .044 38917.454 3 6370.0 -.015 16650.720 2 473.5 .068 38934.396 1 6374.5 -.067 16933.843 4 548.5 -.029 38972.330 2 6384.5 .104 16935.791 4 549.0 .031 39289.447 2 6468.5 .014 17037.670 2 576.0 -.051 39291.433 1 6469.0 .113 17394.618 3 670.5 .039 39325.335 2 6478.0 .027 17728.804 4 759.0 .024 39683.999 2 6573.0 -.055 18098.805 2 857.0 -.049 39684.042 2 6573.0 -.012 18119.581 2 862.5 -.042 39702.922 2 6578.0 -.012 18427.378 3 944.0 -.012 39702.938 2 6578.0 .002 18436.830 4 946.5 -.001 40393.940 2 6761.0 -.054 18440.537 2 947.5 -.070 40394.010 4 6761.0 .017 18453.802 4 951.0 -.022 40412.820 2 6766.0 -.055 18457.676 1 952.0 .075 40412.983 2 6766.0 .107 18472.699 3 956.0 -.007 40711.127 2 6845.0 -.073 18506.687 3 965.0 -.005 40711.193 2 6845.0 -.007 18825.737 3 1049.5 -.051 40746.999 2 6854.5 -.076 18859.705 3 1058.5 -.069 40747.023 1 6854.5 -.053 19233.664 3 1157.5 .038 40763.992 2 6859.0 -.076 19250.603 3 1162.0 -.016 40764.039 2 6859.0 -.030 19303.537 2 1176.0 .050 41066.077 2 6939.0 -.094 19516.772 2 1232.5 -.073 41066.194 4 6939.0 .023 19518.738 4 1233.0 .004 41528.899 2 7061.5 .135 19550.708 2 1241.5 -.125 42538.909 4 7329.0 -.010 19888.835 2 1331.0 .026 42542.710 4 7330.0 .014 19922.754 2 1340.0 -.042 19922.821 4 1340.0 .025 20330.675 2 1448.0 .041 20366.590 2 1457.5 .081 20755.506 2 1560.5 .040 20932.863 3 1607.5 -.087 21391.707 2 1729.0 -.061 ------------------------------------------------------------------------ [FIGURE 1] The photoelectric measurements show a depth of primary minimum of about 0.6m. The light stays nearly constant during maximum; due to bad weather conditions, the secondary minimum could not be observed but the number of photographic secondary minima indicates about equal depth of both minima. We are grateful to the European Southern Observatory for providing observing time to one of us (J.R.) at the 50 cm photoelectric telescope in Chile. JURGEN RAHE EBERHARD SCHOFFEL Remeis-Observatory Bamberg References: Bauernfeind, H., 1968, Veroff.Bamberg, Vol. VIII, N. 81 Strohmeier, W., Knigge, R., and Ott, H., 1964, IBVS No. 74