COMMISSION 27 OF THE I.A.U. INFORMATION BULLETIN ON VARIABLE STARS Number 2906 Konkoly Observatory Budapest 11 June 1986 HU ISSN 0374 - 0676 PHOTOMETRIC OBSERVATION OF VISUAL DOUBLE STAR ADS 9537 (BV Dra, BW Dra) BY AREA SCANNING TECHNIQUE The two W UMa-type stars, BV Dra and BW Dra, members of the visual binary system ADS 9537, have been observed during eleven nights between February 8, 1984 and April 24, 1984. Photoelectric B, V observations were made with the 45 cm reflector at the Urals University observatory with the aid of the area scanning technique, proposed by Rakosch (1965) and Franz (1966). The diameter of the seeing disk of the star image during the observational nights was 8"-15". The angular separation of the visual binary system being about 16.3" (Yamasaki, 1979), the diameter of the seeing disk was of the same size or smaller than the separation of components. That is why it was necessary to use the area scanning technique. The scanning of the stellar images was realized by rotation of the four-side glass prism. The slit width used was 15". The scans, each consisting of 64 ten ms integrations of pulses arriving from the pulse-amplifier, were stored in the computer's memory. The profile data were typically obtained by summing of 80 scans by the method adopted by Warner et al. (1983). Reduction of the profile was made by the method similar to that described by Franz (1970, 1973). The comparison star was BD+62 1385. A total of 171 observations in V and 108 in B for both BV Dra and BW Dra were obtained. The scatter of the individual magnitudes m = m(var.)-m(comp.) near their mean light curves corresponds to standard deviations of +-0.015 and +-0.016 magnitudes in V and B, respectively. The times of minima that were obtained by present observations are represented in Table I for BV Dra and Table II for BW Dra respectively. The successive columns contain the heliocentric JD, the type of minimum, the O-C residuals for our minima times in two cases; using Yamasaki's ephemeris, O-C_I and our O-C_II. [FIGURE 1] [FIGURE 2] Table I JD_Hel type O-C_I O-C_II min. 2445000+ 739.2897 II +0.0052d +0.0002d 740.3394 II +0.0046 +0.0003 740.5131 I +0.0032 -0.0017 753.2920 II +0.0048 -0.0004 761.5191 I +0.0054 +0.0001 762.2192 I +0.0054 -0.0001 762.3937 II +0.0048 -0.0006 763.2731 I +0.0091 +0.0037 802.3026 II +0.0063 +0.0003 813.3291 I +0.0057 -0.0005 814.3792 I +0.0056 -0.0006 Table II JD_Hel type O-C_I O-C_II min. 2445000+ 740.3621 II +0.0195d +0.0016d 740.5052 I +0.0165 -0.0014 753.3615 I +0.0175 -0.0004 761.2500 I +0.0175 -0.0003 762.2726 II +0.0175 -0.0004 762.4190 I +0.0179 -0.0001 763.2956 I +0.0180 +0.0001 782.4332 II +0.0187 +0.0008 802.3007 II +0.0190 +0.0012 814.2782 II +0.0177 -0.0001 814.4234 I +0.0168 -0.0010 The times of minima do not agree well with the epochs given by Yamasaki (1979) for those two stars. New period and epochs were determined as follows: JD_Hel minI = 2445739.1145 + 0.350071d E for BV Dra and JD_Hel minI = 2445740.2144 + 0.292165d E for BW Dra respectively. Figure 1 and 2 represent B and V light curves for BV Dra and BW Dra respectively. S.Yu. GORDA Astronomical observatory of Ural University, Sverdlovsk USSR References: Franz O.G., 1966, Lowell Observ. Bull. 6, 15, 251. [BIBCODE 1966LowOB...6..251F ] Franz O.G., 1970, Lowell Observ. Bull. 7, 17, 191. [BIBCODE 1970LowOB...7..191F ] Franz O.G., 1973, J. Roy. Astron. Soc, Can., 67, 81. [BIBCODE 1973JRASC..67...81F ] Rakosch K.D., 1965, Appl. Opt., 4., 1453. [BIBCODE 1965ApOpt...4.1453R ] Warner B., Hurly, P.R., and Nather, R.E. 1983, Mon. Not. R. Astr. Soc., 202, 753. [BIBCODE 1983MNRAS.202..753W ] Yamasaki A., 1979, Astrophys, and Space Sci., 60, I, 173. [BIBCODE 1979Ap&SS..60..173Y ]