COMMISSION 27 OF THE I. A. U. INFORMATION BULLETIN ON VARIABLE STARS Number 962 Konkoly Observatory Budapest 1975 January 31 PHOTOELECTRIC LIGHTCURVE AND MINIMA OF THE ECLIPSING BINARY CW Cas During 1972 we have observed photoelectrically the eclipsing binary CW Cas with the 40 cm refractor of the Teramo Observatory. The observations have been performed with a conventional photometer equipped with an E.M.I. 9502 photomultiplier and Schott GG 14 + GG 13 (2 mm) filters for the V light and Schott BG 12 + GG 13 (2 mm) for the B one. The comparison and check stars are respectively the "a" and "b" stars used by Broglia (1957) : the coordinates, the V and B-V magnitudes are given in Table I. Table I Star R.A. 1975 D.1975 V B-V a 00h43m58s + 62deg59'.5 10m.72+-0.03 0.94+-0.03 b 00 44 16 + 63 00. 5 10. 79+-0.04 0.44+-0.04 From the observed seven minima we have computed the new elements by a least squares solution, obtaining Min I = JD_{hel} 2441649.40322+ 0.3188449 +-.00005 +-.0000028 The difference from the Broglia's period (1964) Delta(P)=0.00002 is much greater than the error and this suggests a variation of the period; a confirmation is given from the systematic trend of the O-C's for all the minima available in the literature, but the data are insufficient for a valuable determination of a variability law. In Table II are listed the epochs and their errors, computed by the Hertzsprung's method, and the computed O-C's. Table II Observed minima E O-C Date Mean error JD_{hel}2441 632.34501 +-0.00049 - 53.5 - 0.00001 634.41764 .00011 - 47.0 + 0.00013 649.40339 .00008 0 + 0.00017 650.35954 .00027 3.0 - 0.00021 650.51889 .00015 3.5 - 0.00029 658.33083 .00008 28.0 - 0.00005 658.49059 .00026 28.5 + 0.00029 The composite yellow light curve is drawn in the figure. JD_{hel} Delta V JD_{hel} Delta V JD_{hel} Delta V JD_{hel} Delta V 2441542. 2441634. 2441649. 2441649. .4928 0.32 .2918 .47 .3180 .28 .5386 .56 .4968 .38 .2952 .40 .3213 .30 .5424 .51 .5007 .30 .2991 .38 .3246 .29 2441650. .5049 .31 .3062 .34 .3280 .28 .2402 .38 .5083 .31 .3062 .35 .3314 .30 .2435 .35 .5112 .31 .3091 .32 .3380 .30 .2464 .39 .5147 .35 .3120 .35 .3413 .30 .2507 .37 .5213 .33 .3151 .33 .3445 .35 .2535 .33 .5252 .35 .3209 .30 .3477 .38 .2565 .30 .5288 .36 .3236 .30 .3510 .36 .2594 .33 .5319 .38 .3277 .25 .3544 .39 .2623 .31 .5351 .41 .3309 .25 .3579 .39 .2650 .29 .5381 .40 .3358 .27 .3658 .45 .2702 .32 .5416 .41 .3391 .30 .3692 .47 .2736 .28 .5464 .42 .3439 .30 .3727 .48 .2827 .27 .5498 .50 .3469 .31 .3760 .56 .2857 .25 .5530 .59 .3516 .27 .3797 .56 .3004 .33 .5562 .62 .3549 .30 .3833 .65 .3040 .36 .5595 .64 .3578 .32 .3866 .65 .3074 .34 .5630 .64 .3610 .32 .3899 .78 .3112 .38 .5662 .73 .3754 .42 .3935 .86 .3144 .37 .5696 .73 .3798 .43 .3984 .87 .3190 .44 .5745 .86 .3873 .54 .4020 .90 .3221 .45 .5778 .89 .3908 .58 .4055 .92 .3254 .47 .5810 .91 .3943 .59 .4093 .86 .3287 .50 .5842 .89 .3976 .65 .4129 .84 .3321 .53 .5873 .91 .4011 .67 .4163 .78 .3321 .53 .4047 .78 .4197 .71 .3357 .59 2441632. .4116 .87 .4232 .60 .3391 .64 .3122 0.43 .4151 .89 .4283 .52 .3423 .67 .3175 .49 .4187 .87 .4320 .53 .3465 .76 .3159 .57 .4225 .88 .4353 .53 .3494 .80 .3218 .53 .4264 .87 .4386 .48 .3524 .86 .3238 .53 .4301 .74 .4422 .45 .3554 .88 .3258 .60 .4336 .71 .4459 .46 .3583 .87 .5289 .67 .4375 .62 .4493 .41 .3614 .88 .3309 .71 .4409 .57 .4547 .36 .3661 .81 .3329 .71 .4583 .35 .3691 .82 .3350 .71 2441649. .4620 .35 .3722 .78 .3368 .70 .2450 .82 .4675 .29 .3750 .71 .3388 .72 .2481 .79 .4712 .31 .3781 .70 .3405 .72 .2526 .75 .4753 .31 .3811 .64 .3424 .72 .2562 .72 .4807 .28 .3843 .58 .3443 .76 .2601 .67 .4840 .29 .3872 .55 .3465 .73 .2684 .50 .4876 .33 .3915 .52 .3484 .77 .2717 .52 .4911 .29 .3943 .47 .3516 .74 .2747 .48 .4970 .28 .3976 .43 .3535 .75 .2780 .45 .5004 .32 .4007 .47 .3557 .62 .2813 .45 .5039 .38 .4043 .45 .3575 .62 .2846 .39 .5076 .37 .4074 .39 .2893 .42 .5153 .32 .4111 .39 2441634. .2924 .38 .5167 .38 .4140 .37 .2754 .59 .2958 .35 .5206 .35 .4200 .33 .2785 .58 .2994 .32 .5247 .46 .4229 .32 .2814 .50 .3184 .34 .5289 .45 .4262 .32 .2844 .49 .3146 .29 .5347 .50 .4294 .28 .2873 .49 JD_{hel} delta V JD_{hel} delta V JD_{hel} delta V JD_{hel} delta V 2441650. 2441658. 2441658. 2441660. .4353 .30 .3107 .61 .4239 .31 .2172 .53 .4386 .28 .3124 .65 .4261 .33 .2222 .64 .4417 .28 .3143 .69 .4283 .31 .2242 .60 .4448 .30 .3161 .78 .4303 .32 .2265 .67 .4498 .31 .3181 .80 .4324 .32 .2287 .68 .4530 .31 .3201 .83 .4345 .32 .2310 .84 .4565 .30 .3221 .83 .4366 .34 .2594 .74 .4594 .33 .3241 .90 .4385 .34 .2613 .71 .4628 .33 .3259 .88 .4405 .38 .2631 .66 .4661 .34 .3287 .88 .4454 .36 .2650 .63 .4707 .37 .3306 .87 .4473 .36 .2668 .60 .4738 .41 .3324 .92 .4493 .37 .2687 .57 .4770 .41 .3342 .90 .4513 .38 .2713 .52 .4799 .43 .3363 .89 .4532 .40 .2731 .55 .4862 .46 .3382 .88 .4552 .42 .2748 .53 .4894 .48 .3402 .84 .4573 .42 .2766 .51 .4932 .54 .3422 .83 .4591 .50 .2784 .47 .4963 .57 .3443 .79 .4613 .48 .2802 .45 .5017 .57 .3462 .74 .4637 .49 .2820 .43 .5052 .68 .3480 .69 .4659 .50 .2861 .38 .5087 .71 .3501 .66 .4680 .53 .2880 .36 .5118 .76 .3530 .59 .4702 .59 .2899 .37 .5150 .77 .3548 .59 .4725 .61 .2917 .41 .5183 .78 .3566 .55 .4747 .64 .2935 .37 .5231 .73 .3585 .55 .4768 .68 .2953 .37 .5259 .73 .3603 .53 .4791 .69 .2979 .34 .5291 .75 .3623 .48 .4820 .69 .2995 .28 .5322 .67 .3643 .47 .4844 .71 .3096 .26 .5386 .57 .3661 .47 .4867 .77 .3112 .29 .5415 .56 .3680 .43 .4893 .77 .3129 .34 .5447 .52 .3699 .40 .4914 .76 .3145 .34 .5479 .53 .3719 .39 .4937 .78 .3175 .25 .5528 .50 .3739 .40 .4960 .76 .3211 .32 .5559 .47 .3758 .36 .4981 .73 .3226 .29 .5594 .44 .3780 .38 .5001 .71 .3331 .28 .5626 .40 .3799 .35 .5023 .68 .3350 .32 .5674 .37 .3820 .36 .5062 .60 .3369 .31 .5705 .36 .3837 .33 .5086 .63 .3389 .28 .5737 .34 .3858 .35 .5107 .61 .3409 .25 .5770 .32 .3886 .31 .5131 .55 .3428 .31 .5818 .34 .3907 .30 .5152 .55 .5446 .31 .5847 .31 .3925 .32 .5174 .54 .3466 .32 .5883 .29 .3942 .31 .5200 .49 .3487 .35 .5915 .27 .3961 .31 .5226 .42 .3505 .33 .5973 .32 .3980 .28 .5249 .45 .3531 .34 .6002 .31 .3997 .28 .5275 .42 .3549 .33 .6032 .31 .4017 .30 .5295 .40 .3566 .38 .6061 .27 .4038 .28 .5320 .41 .3582 .37 2441658. .4057 .32 .5342 .37 .3614 .40 .2899 .41 .4076 .30 .5374 .37 .3631 .38 .2920 .43 .4117 .28 .5396 .37 .3648 .38 .2938 .42 .4135 .30 2441660. .3665 .40 .2959 .44 .4155 .28 .2056 .43 .3685 .38 .3043 .56 .4174 .27 .2106 .51 .3701 .41 .3063 .60 .4196 .28 .2129 .46 .3818 .60 .3089 .58 .4216 .29 .2150 .48 .3837 .58 .3852 .58 [FIGURE 1] Yellow light curve of CW Cas (1972) Teramo Astronomical Observatory R. BURCHI I - 64100 Teramo R. DE SANTIS References: Broglia, P., 1957, Merate Contr. N. 113 Broglia, P., 1964, Mem. Soc. Astron. Italiana 35, 23 [BIBCODE 1964MmSAI..35...23B ]