COMMISSION 27 OF THE I. A. U. INFORMATION BULLETIN ON VARIABLE STARS Number 1007 Konkoly Observatory Budapest 1975 June 12 BW BOOTIS - AN ALGOL TYPE ECLIPSING VARIABLE The star BW Boo (HD 128661 = BD +36d2509) was reported by Jackisch (1968) and Harris (1969) to be probably an eclipsing variable. The solution of its spectroscopic orbit by Gorza (1971) gives P = 3.33284(2)d Phi^d_II = 1.51d where P is the period of radial velocity variation and Phi^d_II is the phase in days of the eccentric secondary minimum. Photoelectric observations were made on 10 nights in yellow and on 3 nights in blue colours with the 20 cm Grubb f/12 refractor at the Cracow Astronomical Observatory Fort Skala. An uncooled photomultiplier FEU-17 manufactured in USSR (antimony - caesium cathode) together with the standard Schott filters for blue and yellow were used. In the reduction to Johnson's BV system the formulae derived by Dworak and Winiarski (1972) were adopted. The comparison and check stars were BD+36d2568 and BD +36d2530, respectively. No variation has been noticed between them. Two times of primary minimum were determined and listed in Table I together with moments published by Jackisch and Harris. The O-C values were calculated with the new elements JD hel Min I = 2440 362.9026 + 3.332821d E. Table II contains the observations in V and Table III gives the results of observations in B made on 2 nights near the primary minimum and on one night on the constant maximum. All measurements were corrected for differential extinction. DeltaV and DeltaB represent the corresponding brightnesses in magnitudes of the variable minus those of the comparison. The phases are calculated using recently derived elements. The light curve in V is presented on the Figure 1. BW Bootis seems to be an Algol type eclipsing system with the following properties: range of light variation primary minimum DeltaV = 0.260m DeltaB = 0.290m secondary minimum DeltaV = 0.035m lack of data total duration of minima primary D I = 4h90m secondary D II = about 4h50m deplacement of secondary from the phase 0.5 about -0.166d phase of secondary = 1.50d Because of the uneven distribution of the phases of our observations a more detailed discussion of the period is not possible. Observations of BW Boo carried out at different geographical longitude are necessary to complete our knowledge on this variable. Table I. Times of primary minima ----------------------------------------- JD hel O-C E Observer ----------------------------------------- 2438906.4578 -0.0020 -437 Jackisch 40362.9070 +0.0040 0 Harris 41682.6960 -0.0037 +396 Kurpinska 42152.6260 -0,0027 +537 Kurpinska ----------------------------------------- Table II. Observations in V ---------------------------------------------------------------------------- JD hel DeltaV JD hel DeltaV JD hel DeltaV ---------------------------------------------------------------------------- 2441680.5806 -0.155 2491683.6411 -0.169 2441767.4901 -0.131 681.5416 -0.166 .6468 -0.151 .4984 -0.118 .5450 -0.155 .6490 -0.160 .5231 -0.132 .5540 -0.167 .6550 -0.148 .5283 -0.128 682.5781 -0.162 .6570 -0.161 .5301 -0.136 .5812 -0.130 .6820 -0.165 .5565 -0.125 .5866 -0.120 .6843 -0.167 .5589 -0.129 .5896 -0.140 .6907 -0.146 .5707 -0.144 .5959 -0.163 .6927 -0.163 .5815 -0.134 .6133 -0.101 .7147 -0.164 .5870 -0.142 .6192 -0.103 709.5907 -0.147 .5947 -0.152 .6264 -0.135 .6097 -0.149 .5970 -0.161 .6327 -0.052 .6117 -0.162 .6030 -0.149 .6972 -0.022 .6240 -0.153 .6058 -0.156 .6500 +0.002 .6259 -0.141 .6134 -0.146 .6575 +0.041 .6361 -0.163 .6155 -0.155 .6687 +0.020 .6386 -0.149 2442152.4969 -0.173 .6766 +0.092 .6490 -0.149 .4981 -0.143 .6798 +0.101 746.4860 -0.155 .5005 -0.158 .6894 +0.068 .4966 -0.144 .5024 -0.142 .6942 +0.084 .4992 -0.160 .5062 -0.153 .6995 +0.063 .5076 -0.164 .5075 -0.161 .7023 +0.098 .5098 -0.159 .5148 -0.147 .7096 +0.073 .5194 -0.161 .5161 -0.134 .7200 +0.061 .5256 -0.138 .5225 -0.134 .7230 +0.040 .5385 -0.144 .5239 -0.153 .7252 +0.022 758.4037 -0.157 .5300 -0.142 .7323 +0.024 .4177 -0.168 .5314 -0.159 683.6142 -0.171 .4205 -0.153 .5366 -0.134 .6162 -0.150 .5052 -0.162 .5378 -0.145 .6222 -0.157 .5166 -0.152 .5429 -0.103 .6247 -0.144 767.4454 -0.130 .5441 -0.096 .6302 -0.138 .4516 -0.138 .5511 -0.086 .6332 -0.148 .4648 -0.123 .5529 -0.108 .6399 -0.145 .4732 -0.130 .5572 -0.068 ---------------------------------------------------------------------------- Table II cont. --------------------------------------------------------------------- JD hel DeltaV JD hel DeltaV JD hel DeltaV --------------------------------------------------------------------- 2442152.5597 -0.096 2442493.5597 -0.147 2442493.5799 -0.146 .5691 -0.061 .5608 -0.158 .5812 -0.148 .5701 -0.059 .5630 -0.153 .5835 -0.155 .5723 -0.031 .5642 -0.148 .5845 -0.157 493.5483 -0.155 .5663 -0.154 .5869 -0.148 .5494 -0.146 .5674 -0.152 .5882 -0.153 .5519 -0.141 .5697 0.150 .5899 -0.154 .5532 -0.146 .5717 -0.160 .5911 -0.159 .5556 -0.156 .5752 -0.169 .5935 -0.148 .5567 -0.167 .5774 -0.154 --------------------------------------------------------------------- Table III. Observations in B --------------------------------------------------------------------- JD hel DeltaB JD hel DeltaB JD hel DeltaB --------------------------------------------------------------------- 2441682.5781 -0.183 2442152.4981 -0.188 2442993.5494 -0.197 .5812 -0.220 .5005 -0.188 .5519 -0.188 .5866 -0.181 .5024 -0.183 .5532 -0.182 .5896 -0.186 .5062 -0.145 .5556 -0.190 .5959 -0.216 .5075 -0.170 .5567 -0.193 .6091 -0.150 .5148 -0.187 .5597 -0.185 .6133 -0.124 .5161 -0.179 .5608 -0.194 .6192 -0.114 .5226 -0.154 .5630 -0.182 .6327 -0.154 .5239 -0.164 .5642 -0.177 .6472 -0.038 .5300 -0.173 .5663 -0.179 .6500 -0.023 .5314 -0.176 .5674 -0.189 .6575 -0.034 .5366 -0.156 .5697 -0.184 .6590 +0.007 .5378 -0.172 .5717 -0.188 .6687 +0.097 .5429 -0.139 .5752 -0.177 .6690 +0.071 .5441 -0.124 .5774 -0.188 .6766 +0.090 .5511 -0.145 .5799 -0.177 .6798 +0.084 .5529 -0.116 .5812 -0.177 .6913 +0.106 .5572 -0.084 .5835 -0.171 .7023 +0.104 .5597 -0.104 .5845 -0.173 .7200 +0.019 .5691 -0.098 .5869 -0.181 .7230 +0.055 .5701 -0.081 .5882 -0.176 .7323 0.000 .5723 -0.046 .5899 -0.175 2442152.4969 -0.211 493.5483 -0.194 .5935 -0.179 --------------------------------------------------------------------- MARIA KURPINSKA Astronomical Observatory of the Jagellonian University, 31-501 Krakow, Poland. References: Dworak, Z.T., Winiarski, M., 1972, Acta Astr. vol. 22, 33 [BIBCODE 1972AcA....22...33D ] Groza, W., Heard, J.F., 1969, I.B.V.S. No. 396 Harris, A.J., 1969, I.B.V.S. No. 365 Jackisch, G., 1968, I.B.V.S. No. 314 [FIGURE 1] Fig. 1. Light curve of BW Bootis