COMMISSION 27 OF THE I. A. U. INFORMATION BULLETIN ON VARIABLE STARS Number 3608 Konkoly Observatory Budapest 21 May 1991 HU ISSN 0374 - 0676 A PERIOD ANALYSIS OF V505 SAGITTARII The variable star V505 Sgr (HR 7571, HD 187949) was discovered to be an eclipsing binary by Hoffmeister (1934). Its first photoelectric light curves were obtained by Oosterhoff in 1950 and were analysed by Kwee (1953) and Horak (1967, 1968); meanwhile the system has been observed by Sofronitsky (1953) and Magalashvili and Razmadze (1953). Moreover, V505 Sgr was observed in 1969 by Chambliss (1972). Since it had not been observed for more than 20 years, it was included in our observational programme for 1990. But, unfortunately, only some parts of its light curves were obtained and V505 Sgr will be re-observed this year. Here a study of its period is presented. Lause (1938) was the first to determine an ephemeris formula for V505 Sgr: Min I (Hel.JD) = 2425501.376 + 1.1828711d * E (1.1) which was based on photographic and visual observations made between 1928 and 1937. In 1953 Kwee proposed the following ephemeris for V505 Sgr: Min I (Hel.JD) = 2433515.3295 + 1.18287141d * E (1.2) while Chambliss (1972), using all data up to 1972, improved equation (1.1) to the linear: Min I (Hel.JD) = 2425501.4017 + 1.18286730d * E (1.3) and to the quadratic one: Min I (Hel.JD) = 2425501.3706 + 1.18287511d E - 4.288dx10^-10*E^2 (1.4) All the minima times of V505 Sgr found in the literature, after Chambliss' work (1972) up to now, are given in Table I. Only three of them (IBVS No. 2185, 1982; BBSAG No. 59, 1982 and that given in the present work, taken with a k filter) are photoelectric, while the rest of them are visual. The successive columns of Table I give: the Hel.JD; the E_c and (O-C)_c according to the linear ephemeris of Chambliss; the E_M and the corresponding (O-C)_M according to Kholopov's et al. (1985) ephemeris formula and the reference. When we combine the old minima times of V505 Sgr, given by Chambliss (1972), with the new ones (those of Table I), a least-squares solution yields to the following ephemeris formulae according to the fitting and the Table I New Minima times of V505 Sagittarii Hel. JD E_C (O-C)_C E_M (O-C)_M Reference 2440000.+ (days) 2274.461 14180 +.001 -1849 -.001 2617.490 14470 -.001 -1559 -.005 Rocznik No 47,1976 3088.274 14868 +.001 -1161 -.004 " 48,1977 3348.499 15038 -.004 - 941 -.010 BBSAG No 31,1977 3348.515 15088 +.012 - 941 +.006 " No 34,1977 3348.517 15088 +.014 - 941 +.008 " " 3367.446 15104 +.017 - 925 +.011 " 3367.410 15104 -.019 - 925 -.025 " No 35,1977 3367.434 15104 +.005 - 925 -.001 " " 3367.437 15104 +.008 - 925 +.002 " " 3368.627 15105 +.016 - 924 +.009 IBVS No 1502,1978 3399.360 15131 -.007 - 898 -.007 BBSAG No 35,1977 3405.310 15136 +.029 - 893 +.023 " 3425.406 15153 +.016 - 876 +.010 " 3691.548 15378 +.013 - 651 +.006 BBSAG No 38,1978 3704.552 15389 +.006 - 640 -.002 " " 3717.551 15400 -.007 - 629 -.014 " " 3717.567 15400 +.005 - 629 +.002 " " 3717.577 15400 +.019 - 629 +.012 " " 3723.471 15405 -.001 - 624 -.009 " " 3730.580 15411 -.011 - 618 +.003 " " 3730.590 15411 -.021 - 618 +.013 " " 3742.387 15421 -.011 - 608 -.018 BBSAG No 38,1978 3748.318 15426 +.006 - 603 -.001 " " 4046.416 15678 +.021 - 351 +.013 " No 46,1980 4072.434 15700 +.016 - 329 +.008 BBSAG No 44,1979 4072.436 15700 +.018 - 329 -.002 " " 4079.542 15706 +.027 - 323 -.021 " " 4079.516 15706 +.001 - 323 -.007 BBSAG No 45,1979 4091.364 15716 +.020 - 313 +.009 BBSAG No 44,1979 4117.374 15738 +.007 - 291 -.001 " " 4117.378 15738 +.011 - 291 +.003 " " 4143.399 15760 +.009 - 269 +.001 BBSAG No 45,1979 4181.245 15792 +.003 - 237 +.006 " " 4435.572 16007 +.014 - 22 +.004 BBSAG No 49,1980 4441.482 16012 +.009 - 17 -.000 " 4461.590 16029 +.010 0 -.001 IBVS No 2185,1982 4499.429 16061 -.004 + 32 -.014 BBSAG No 50,1980 4707.604 16237 -.014 + 208 -.024 BBSAG No 54,1981 4816.450 16345 +.021 + 300 -.002 BBSAG No 56,1981 4816.462 16329 +.008 + 300 +.010 BBSAG No 59,1981 4835.389 16329 +.020 + 316 +.011 BBSAG No 69.1983 4912.276 16410 +.022 + 381 +.011 BBSAG No 57,1981 4925.280 16421 .015 + 392 +.005 " " 5172.502 16630 .017 + 601 +.005 BBSAG No 62,1982 5172.504 16630 .019 + 601 +.007 " " 5178.425 16635 .026 + 606 +.014 " " 5191.434 16646 .023 + 617 +.012 " 5543.284 16943.5 .030 + 914.5 -.043 BBSAG No 69,1983 5560.483 16958 .018 + 929 +.005 " " 5909.436 17253 .025 +1224 +.011 BBSAG No 73,1984 5909.439 17253 .028 +1224 +.013 " No 74 " 6271.402 17559 .034 +1530 +.018 BBSAG No 78,1985 6297.415 17581 .023 +1552 +.008 " " 7384.465 18500 .018 +2471 +.001 BBSAG No 90,1989 7740.514 18801 .024 +2772 +.003 BBSAG No 92,1989 7740.519 18801 .029 +2772 +.008 " No 93, " 7746.431 18806 .027 +2777 +.006 " No 93, " 8058.7025 19070 .021 +3041 -.005 Present Study 8102.472 19107 .025 +3078 +.003 BBSAG No 96,1990 [FIGURE 1] Figure 1: The (O-C) diagram of V505 Sgr according to Chambliss (1972) ephemeris formula. A linear least-squares fitting has been applied to all the data (+: old data; [square]: new ones). [FIGURE 2] Figure 2: The (O-C) diagram of V505 Sgr according to Chambliss (1972) ephemeris formula. Both the old (+) and the new ([square]) data have been approached by a quadratic least squares fitting but each one separately from the other. ephemeris used. Thus, for Chambliss (1972) ephemeris and linear fitting, we find: Min I (Hel.JD)=2425501.3809 + 1.182869365d*E (1.5) and for quadratic: Min I (Hel.JD) = 2425501.3501 + 1.18287707d E - -4.283dx10^-10*E^2 (1.6) while for Kholopov's et al. (1985) ephemeris and linear fitting, we have: Min I (Hel.JD) = 2444461.5932 + 1.18286942d * E (1.7) and for quadratic: Min I (Hel.JD) = 2444461.5933 + 1.18286963d E + 1.49dx10^-11 *E^2 (1.8) The corresponding (O-C) diagram of V505 Sgr for linear fitting and Chambliss (1972) ephemeris is presented in Figure 1, where crosses (+) denote the old data and squares the new ones. (One can get an almost identical diagram for quadratic fitting, without any visible difference. The same is true for Kholopov's et al. (1985) ephemeris). But, if we consider the old and the new data of V505 Sgr separately, then we get Figure 2. In this a quadratic - quadratic least-squares fitting has been applied both to the old data (which according to Chambliss (1972) is much better than the linear one) as well as to the new ones. Unfortunately, there are not minima times of V505 Sgr from 3000E_c to 6000E_c and from 9000E_c to 12000E_c, moreover most of the data are visual exhibiting large scatter. Thus, new minima times of V505 Sgr are needed, and especially photoelectric ones, in order its period behaviour to be examined further. H. ROVITHIS-LIVANIOU P. ROVITHIS and E. ANTONOPOULOU and A. KALIMERIS Section of Astrophysics Astronomical Institute Astronomy and Mechanics National Observatory of Athens Athens University P.O. Box 20048 GR 157 83 Zografos 118 10 Athens, Greece Athens, Greece References: Chambliss, C.R.: 1972, Astron. J. 77, 672. [BIBCODE 1972AJ.....77..672C ] Hoffmeister, C.: 1934, Astron. Nachr. 251, 321. [BIBCODE 1934AN....251..321H ] Horak, T.: 1967, Bull. Astron. Inst. Czech. 18, 331. [BIBCODE 1967BAICz..18..331H ] Horak, T.: 1968, Bull. Astron. Inst. Czech. 19, 149. [BIBCODE 1968BAICz..19..149H ] Kholopov, P.N. et al.: 1985, Fourth Edition of the General Catalogue of Variable Stars, Moscow. Kwee, K.K.: 1953, Bull. Astron. Inst. Neth. 12, 35. [BIBCODE 1953BAN....12...35K ] Lause, F.: 1938, Astron. Nachr. 266, 17. [BIBCODE 1938AN....266...17L ] Magalashvili, N.L. and Razmadze, N.A.: 1953, Peremennye Zvezdy 10, 313. [BIBCODE 1955PZ.....10..313M ] Sofronitsky, A.V.: 1953, Izv. Pulkovo Obs. 19, 151.