COMMISSION 27 OF THE I. A. U. INFORMATION BULLETIN ON VARIABLE STARS Number 1162 Konkoly Observatory Budapest 1976 August 3 UBV PHOTOELECTRIC MINIMA OF SV CENTAURI SV Centauri is a Beta-Lyrae type eclipsing binary known by large period changes. A few UBV photoelectric observations including one primary and one secondary minimum made by the author and B.J. Harris at Perth Observatory in 1974 and 1975 are presented in this paper. The 60cm Lowel-Perth reflector at Perth Observatory and the integrating photometer, described by Millis et al. (1974), were used for measurements. The photometer contains standard UBV filters and EMI 65265 photomultiplier. Each observation consisted of at least three 10 sec integrations in each colour. The variable star and its comparison were observed in the usual sequence CVCVC etc. The star HD 102503 which is of nearly the same colour and only at an angular distance of 5 min of arc from SV Cen served as comparison star. The brightness of the sky background was read after the measurement with each filter. The reduced data in Table I represents time in heliocentric Julian Days and observed differential magnitudes (in telescope- photometer natural system) in the sense variable star minus comparison star, linearly interpolated for the time of the measurement of the variable. The reduction of measured values was performed with the Hewlett-Packard 1900 desk calculator (with extended memory HP 9101A) and both the measured values and the reduced data were plotted simultaneously on the HP 9125B calculator plotter in the way described in a previous paper (Kviz, 1975). The time of minima was computed according to Kwee and van Woerden's (1956) method. The errors given in Table 2 may be spurious, as owing to various circumstances the accuracy of the time of individual measurements in 1974 was hardly better than .001 day. The observations in February 1974 were made by Mr. B.J. Harris, government astronomer, the rest by the author. I wish to express my appreciation to the staff of Perth Observatory for their help during my stay there. For assistance during observations in 1975 I thank Mrs. I.W. Nikoloff from Perth Observatory. Z. KVIZ University of New South Wales Broken Hill Division Broken Hill. N.S.W. 2880 AUSTRALIA. References: Kviz, Z. 1975, Proc. Astr. Soc. Australia 2, 351. [BIBCODE 1975PASAu...2..351K ] Kwee, K.K. and van Woerden, H. 1956, Bull. Astr. Inst. Neth. 12, 327. [BIBCODE 1956BAN....12..327K ] Millis, R.L. et al. 1974, Icarus 23, 425. [BIBCODE 1974Icar...23..425M ] Table I UBV Photoelectric Measurements of SV Centauri JD_hel 2440000.+ DeltaV DeltaB DeltaU 2068.1484 +1.172 2068.1498 +1.195 2068.1519 +1.098 1651 +1.250 1665 +1.229 1679 +1.130 1831 +1.328 1852 +1.305 1866 +1.217 2033 +1.383 2047 +1.391 2060 +1.271 2262 +1.482 2283 +1.486 2297 +1.368 2387 +1.499 2408 +1.509 2429 +1.385 2547 +1.505 2560 +1.485 2581 +1.399 2679 +1.477 2692 +1.454 2706 +1.365 2845 +1.415 2859 +1.406 2873 +1.317 3012 +1.355 3033 +1.334 3047 +1.244 3158 +1.302 3179 +1.273 3199 +1.187 3310 +1.263 3331 +1.246 3345 +1.149 3435 +1.218 3449 +1.205 3463 +1.110 2069.1346 +1.655 2069.1367 +1.681 2069.1380 +1.704 1394 +1.639 1415 +1.649 1429 +1.685 1450 +1.612 1464 +1.612 1485 +1.622 1561 +1.544 1575 +1.552 1589 +1.561 1700 +1.448 1721 +1.441 1735 +1.463 2089 +1.269 2103 +1.271 2117 +1.244 2097.2084 +1.718 2097.2112 +1.720 2097.2133 +1.714 2230 +1.765 2251 +1.831 2265 +1.882 2404 +1.898 2424 +1.930 2445 +1.978 2549 +1.975 2570 +2.046 2591 +2.145 2695 +2.071 2716 +2.110 2737 +2.225 2097.2695 +2.071 2097.2716 +2.110 2097.2737 +2.225 2772 +2.101 2792 +2.108 2813 +2.230 2924 +2.008 2945 +2.004 2966 +2.137 3161 +1.873 3174 +1.835 3195 +1.888 3376 +1.677 3397 +1.677 3417 +1.720 2427.1825 +1.123 2427.1843 +1.113 2427.1849 +1.045 1913 +1.146 1926 +1.164 1940 +1.196 2007 +1.176 2020 +1.178 2036 +1.118 2109 +1.224 2125 +1.215 2136 +1.235 2199 +1.256 2210 +1.247 2427 +1.232 2287 +1.289 2298 +1.276 2310 +1.305 2374 +1.312 2387 +1.301 2398 +1.280 2455 +1.356 2467 +1.347 2479 +1.310 2540 +1.381 2552 +1.380 2564 +1.423 2618 +1.418 2633 +1.419 2659 +1.534 2727 +1.468 2740 +1.483 2751 +1.566 2826 +1.525 2837 +1.549 2848 +1.577 2909 +1.585 2921 +1.605 2932 +1.559 2992 +1.632 3004 +1.647 3016 +1.667 3078 +1.677 3091 +1.719 3101 +1.794 3157 +1.750 3169 +1.775 3179 +1.791 3241 +1.817 3254 +1.840 3265 +1.987 3326 +1.892 3338 +1.909 3349 +2.044 Table II Time of minimum T min sigma Primary 2097.2754 +- .0006 Secondary 2068.2482 +- .0005