COMMISSIONS 27 AND 42 OF THE IAU INFORMATION BULLETIN ON VARIABLE STARS Number 3710 Konkoly Observatory Budapest 17 April 1992 HU ISSN 0374 - 0676 UBVR OBSERVATIONS AND NEW ELEMENTS FOR THE DOUBLE-MODE CEPHEID EW Sct Photoelectric observations of the double-mode Cepheid EW Sct were carried out in summer-autumn 1991. The 60-cm reflector of the Mt. Maidanak observatory of the Tashkent Astronomical Institute was used and 81 UBVR measurements (Table 1) were obtained. [FIGURE 1] Figure 1 The light curves of double-mode Cepheid EW Sct with period P(1) in different phase intervals of period P(0): 0-0.1 (a), 0.1-0.2 (b), 0.2-0.3 (c), 0.3-0.4 (d), 0.4-0.5 (e), 0.5-0.6 (f), 0.6-0.7 (g), 0.7-0.8 (h), 0.8-0.9 (i) and 0.9-1.0 (k) Table 1 JD hel 2448000+ V U-B B-V V-R 418.4566 7.897 1.361 1.691 1.567 419.3896 7.854 1.339 1.737 1.542 420.3850 7.868 1.395 1.746 1.605 425.4088 7.921 1.381 1.741 1.598 426.3508 8.128 1.472 1.832 1.648 427.3879 8.209 1.505 1.826 1.665 428.3896 8.039 1.362 1.740 1.537 429.4016 7.891 - 1.708 1.571 430.3802 7.929 1.371 1.723 1.573 436.3674 7.665 - 1.591 1.501 437.3780 7.913 - 1.745 1.587 438.3748 8.171 - 1.850 1.721 439.3599 8.259 - 1.849 1.690 440.3647 8.001 - 1.722 1.594 443.3258 8.012 - 1.762 1.610 444.3185 8.020 - 1.781 1.616 445.3226 8.038 - 1.788 1.615 448.3133 7.720 1.310 1.629 1.517 449.3679 7.898 - 1.737 - 451.3084 8.284 - 1.875 1.680 453.3259 7.774 1.370 1.640 1.537 454.3407 7.982 - 1.763 1.606 455.3470 8.086 - 1.806 - 456.3415 8.091 - 1.783 1.629 457.3451 8.020 - 1.771 1.613 458.3158 8.052 1.442 1.768 1.618 458.2750 7.891 1.349 1.700 1.565 460.3452 7.785 1.317 1.676 1.541 461.2821 7.903 - 1.739 1.589 462.2919 8.205 1.483 1.840 1.698 463.2567 8.249 1.539 1.836 1.640 464.2640 7.913 1.332 1.676 1.539 465.3253 7.726 1.322 1.618 1.502 466.3234 7.966 - 1.777 1.605 467.3220 8.172 - 1.835 1.664 472.3820 7.811 1.508 1.680 1.549 473.3265 7.917 1.398 1.716 1.567 474.3175 8.127 1.535 1.754 1.632 475.3035 8.186 1.570 1.791 1.632 477.2465 7.704 1.295 1.594 1.508 478.2428 7.984 1.452 1.744 1.559 479.3143 8.194 - 1.896 1.681 480.2405 8.235 1.516 1.822 1.678 481.2696 7.946 1.342 1.687 1.590 482.2729 7.865 - 1.686 1.576 484.2437 8.007 1.409 1.758 1.614 485.2175 7.984 1.428 1.756 1.615 486.2174 8.079 1.493 1.786 1.648 487.2075 8.152 1.487 1.803 1.656 488.1834 7.637 1.336 1.648 1.551 489.2084 7.735 1.350 1.630 1.537 490.2253 7.935 1.436 1.728 1.610 491.2338 8.184 1.576 1.884 1.668 493.2133 7.851 1.349 1.870 1.553 498.2444 8.043 1.451 1.774 1.620 499.2183 8.053 1.436 1.766 1.620 503.2047 8.181 - 1.853 1.689 504.2192 8.247 - 1.838 1.669 505.1814 7.800 - 1.642 1.542 506.1804 7.752 - 1.652 - 507.2121 8.023 - 1.775 1.637 508.2044 8.163 1.514 1.843 1.667 508.1937 8.124 - 1.804 - 510.1872 7.967 - 1.727 1.596 511.1925 7.959 - 1.729 1.600 512.1997 7.892 1.378 1.696 1.580 513.1875 7.881 - 1.694 - 514.1820 7.947 1.415 1.750 1.603 515.1931 8.162 1.493 1.629 1.677 516.1923 8.204 - 1.829 1.665 517.1863 7.746 - 1.635 1.517 518.2007 7.765 - 1.631 1.550 520.1851 8.224 - 1.950 1.681 521.1427 8.179 - 1.814 1.660 522.1434 7.885 - 1.687 1.571 523.1808 7.888 - 1.685 1.575 536.1421 8.037 1.422 1.777 1.841 537.1260 8.106 1.438 1.789 1.642 541.1507 7.810 1.325 1.648 1.547 542.1124 7.811 1.539 1.670 1.560 543.1275 8.014 1.446 1.761 1.632 [FIGURE 2] Figure 2 The light curves of double-mode Cepheid EW Sct with period P(0) in different phase intervals of period P(1): 0-0.1 (a), 0.1-0.2 (b), 0.2-0.3 (c), 0.3-0.4 (d), 0.4-0.5 (e), 0.5-0.6 (f), 0.6-0.7 (g), 0.7-0.8 (h), 0.8-0.9 (i) and 0.9-1.0 (k) These observations together with the other published ones (Berdnikov, 1992, Figer et al., 1991) allow to improve the periods using the method described by Antonello et al. (1986). The new elements are: Max (0) = JD hel 2446316.5 + 5.823337d E, and Max (1) = JD hel 2446321.2 + 4.06778d E. The observed magnitudes converted into intensities were then expressed as a sum of two oscillations, and light curves of each oscillation were constructed for different phase intervals of the other oscillation. These curves in V band are presented in Figures 1 and 2. A detailed investigation of the light curves of EW Sct in UBVR bands will be published elsewhere. L. BERDNIKOV and S. SKORNYAKOVA University of Saratov, Saratov, Russia M. IBRAGIMOV, V. KONDRATIEV and S. YAKUBOV Astronomical Institute, Tashkent, Republic of Uzbekistan References: Antonello, E., Mantegazza, L. and Poretti, E.: 1986, Astron. and Astrophys., 159, 269. [BIBCODE 1986A&A...159..269A ] Berdnikov, L.N.: 1992, submitted for publication. Figer, A., Poretti, E., Sterken, C. and Walker, N.: 1991, Mon. Not. Roy. Astron. Soc., 249, 563. [BIBCODE 1991MNRAS.249..563F ]