COMMISSION 27 OF THE I. A. U. INFORMATION BULLETIN ON VARIABLE STARS Number 1171 Konkoly Observatory Budapest 1976 September 3 NEW B,V LIGHT CURVES OF SZ LYNCIS The RR_s star SZ Lyn was observed on February 29 and March 3, 1976, with the 36 cm Cassegrain telescope of the Hoher List Observatory. A single channel photometer equipped with a 1P21 multiplier and Schott BG12(1mm)+GG13(2mm) = B, GG11(2mm) = V filters, a conventional amplifier, and a strip chart recorder were used. Following the investigations of van Genderen (1963) and Barnes and Moffett (1975), BD +45d1544 served as a comparison star. We also adopted their data V = 9.43m, B - V = 0.46m for this star. 1. Times of Maximum Light Two times of maximum light were determined by Pogson's method (Schiller 1923). The mean error of a maximum time is about 0.0006d. The O - C's, calculated from Barnes and Moffett's sinusoidal ephemeris, are E t_max (J.D.hel.) O-C 39100 2442837.3091 + 0.0006d 39133 2442841.2875 + 0.0012 [FIGURE 1] Fig. 1. B, V light curves of SZ Lyn, relative to BD +45d1544 2. Light Curves Fig. 1 is composed of 121 B and 122 V observations which are listed in Table 1. Observations of J.D. 2442837 are shown as dots, those of J.D. 2442841 as circles. The light curves do not coincide. Deviations are particularly noticeable in the phase interval 0.0 to 0.6. In the second night, the star appeared bluer during maximum and became redder during later phases. 3. Maximum Light Barnes and Moffett investigated the B magnitude at maximum light of SZ Lyn versus phase in the 1148 day cycle of the period variations and found no correlation. Nevertheless, their own observations indicated an increase in the brightness of SZ Lyn, compared with earlier investigations. This trend seems to continue in our new observations (Fig. 2). Also, the B magnitude at minimum light and the V magnitudes exhibit a similar phenomenon. In order to discriminate the possible secular increase in brightness of SZ Lyn against a decrease of the brightness of BD +45deg1544 and/or difficulties with the transformations of the colour systems of various observers, careful observations during the next seasons are necessary. [FIGURE 2] Fig. 2. Secular variation of the B magnitude at maximum. Data are taken from the compilation of Barnes and Moffett (1975), the two dots are derived by the author from the observations of Joshi and Srivastava (1967); the circle represents the result of a single observing run by Wisse and Wisse (1969) H.W. DUERBECK Observatorium Hoher List Universitats-Sternwarte Bonn 5568 Daun/Eifel, F.R.G. References: Barnes III, Th.G., Moffett, Th.J. 1975, Astr.J. 80, 48 [BIBCODE 1975AJ.....80...48B ] Joshi, S.C., Srivastava, H.N. 1967, Z. Astrophys. 67, 456 [BIBCODE 1967ZA.....67..456J ] Schiller, K. 1923, Einfuhrung in das Studium der veranderlichen Sterne, Leipzig: J.A. Barth. [BIBCODE 1923QB835.S25...... ] van Genderen, A.M. 1963, Bull. astr. Inst. Netherl. 17, 243 [BIBCODE 1963BAN....17..243V ] Wisse, M., Wisse, P.N.J. 1969, Bull. astr. Inst. Netherl. 20, 333 [BIBCODE 1969BAN....20..333W ] Table 1. B, V magnitude differences relative to BD +45d1544 J.D.HEL.. DeltaB J.D.HEL.. DeltaB J.D.HEL. DeltaV J.D.HEL. DeltaV 2442... 2442... 2442... 2442... 837.2756 0.037 837.4099 -.128 837.2771 -.032 837.4056 -.077 .2768 .044 841.2776 -.398 .2807 -.040 .4084 -.111 .2802 .021 .2793 -.473 .2818 -.032 .4094 -.138 .2814 .027 .2830 -.578 .2848 -.071 841.2800 -.442 .2843 0.000 .2843 -.597 .2861 -.086 .2837 -.500 .2855 -.050 .2882 -.620 .2896 -.141 .2852 -.519 .2907 -.153 .2898 -.611 .2911 -.172 .2887 -.529 .2934 -.235 .2936 -.575 .2939 -.231 .2902 -.528 .2970 -.340 .2953 -.570 .2947 -.251 .2936 -.505 .2982 -.393 .2991 -.499 .2976 -.340 .2948 -.499 .3014 -.494 .3007 -.478 .2986 -.363 .2981 -.460 .3023 -.530 .3043 -.452 .3018 -.458 .2984 -.428 .3064 -.591 .3055 -.436 .3028 -.476 .3035 -.410 .3101 -.606 .3087 -.388 .3060 -.510 .3050 -.376 .3132 -.587 .3100 -.372 .3070 -.513 .3080 -.356 .3141 -.582 .3134 -.324 .3096 -.525 .3093 -.344 .3170 -.570 .3149 -.316 .3106 -.523 .3129 -.314 .3185 -.545 .3194 -.266 .3137 -.505 .3144 -.306 .3211 -.506 .3207 -.253 .3146 -.496 .3189 -.246 .3226 -.469 .3248 -.206 .3174 -.470 .3202 -.251 .3255 -.430 .3268 -.188 .3189 -.469 .3241 -.223 .3264 -.430 .3341 -.126 .3215 -.450 .3257 -.209 .3274 -.419 .3384 -.087 .3231 -.432 .3319 -.187 .3299 -.392 .3425 -.070 .3260 -.399 .3335 -.173 .3307 -.371 .3437 -.059 .3268 -.399 .3373 -.141 .3336 -.334 .3453 -.057 .3295 -.360 .3394 -.129 .3354 -.305 .3487 -.030 .3302 -.346 .3432 -.111 .3382 -.297 .3501 -.020 .3364 -.312 .3446 -.103 .3398 -.268 .3538 -.005 .3377 -.298 .3480 -.099 .3424 -.236 .3549 .011 .3389 -.258 .3495 -.100 .3432 -.241 .3589 .020 .3420 -.268 .3533 -.068 .3462 -.216 .3600 .014 .3427 -.259 .3543 -.064 .3480 -.182 .3642 .065 .3459 -.245 .3582 -.046 .3509 -.157 .3653 .042 .3475 -.195 .3596 -.043 .3518 -.155 .3688 .038 .3504 -.174 .3637 -.024 .3544 -.123 .3700 .039 .3512 -.174 .3648 .010 .3562 -.105 .3743 .041 .3540 -.147 .3683 -.009 .3588 -.127 .3759 .035 .3557 -.141 .3693 -.013 .3598 -.101 .3793 .014 .3584 -.127 .3732 -.016 .3629 -.091 .3804 0.000 .3593 -.124 .3750 .002 .3642 -.076 .3836 -.038 .3625 -.108 .3787 -.027 .3669 -.042 .3848 -.071 .3634 -.113 .3799 -.046 .3678 -.034 .3886 -.123 .3664 -.088 .3832 -.075 .3706 -.029 .3898 -.171 .3674 -.077 .3843 -.084 .3714 -.028 .3936 -.171 .3700 -.091 .3877 -.158 .3745 -.009 .3936 -.285 .3710 -.082 .3892 -.172 .3755 .022 .3950 -.322 .3738 -.068 .3927 -.251 .3787 0.000 .3984 -.460 .3749 -.056 .3943 -.283 .3802 .040 .3996 -.491 .3786 -.054 .3977 -.383 .3836 .026 .4009 -.528 .3795 -.042 .3991 -.412 .3847 .018 .4040 -.606 .3828 -.016 .4002 -.440 .3879 .017 .4051 -.616 .3841 -.041 .4014 -.462 .3889 .040 .4064 -.622 .3875 -.026 .4047 -.516 .3919 .038 .4075 -.621 .3884 -.020 .4057 -.519 .3957 .031 .4115 -.604 .3912 -.010 .4068 -.528 .3966 .026 .4126 -.606 .3923 -.018 .4104 -.514 .4007 .002 .4137 -.595 .3952 -.030 .4119 -.512 .4017 -.030 .4168 -.556 .3961 -.021 .4132 -.506 .4051 -.052 .4179 -.544 .4002 -.047 .4163 -.490 .4061 -.061 .4190 -.540 .4012 -.047 .4173 -.487 .4090 -.104 .4046 -.072 .4184 -.475