COMMISSION 27 OF THE I.A.U. INFORMATION BULLETIN ON VARIABLE STARS Number 3266 Konkoly Observatory Budapest 22 November 1988 HU ISSN 0374 - 0676 A NEW PERIOD CHANGE OF BX And The short period eclipsing binary BX And (=BD+ 40d442=HD 13078) is the brighter component of the visual binary ADS 1671. It was announced as a variable star by Soloviev (1945). Its light elements and times of minima have been published by various authors (see references to Table I). BX And was observed at the Ege University Observatory. The observations were made in B and V bands using the 48 cm Cassegrain reflector with a photoelectric photometer equipped with an unrefrigerated photomultiplier tube EMI 9781A. BD +39d476 and BD +39d484 were used as comparison and check stars, respectively. [FIGURE 1] Figure 1 : The O-C diagram for BX And. (Ephemeris: Chou, 1959). Table I. Times of minima of BX Andromedae J.D. Hel. min method E O-C_1 O-C_2 Ref. 2414688.54 I pg -35797 0.06 -0.03 1 966.78 I pg -35341 0.09 0.00 1 15282.80 I pg -34823 0.07 -0.02 1 16371.88 I pg -33038 0.09 0.01 1 860.55 I pg -32237 0.06 -0.02 1 17168.67 I pg -31732 0.07 -0.01 1 18542.70 I pg -29480 0.12 0.05 1 20751.89 I pg -25859 0.08 0.03 1 803.74 I pg -25774 0.08 0.02 1 21089.86 I pg -25305 0.05 -0.01 1 22942.79 I pg -22268 0.06 0.01 1 23019.65 I pg -22142 0.05 0.00 1 24064.77 I pg -20429 0.04 0.00 1 27357.88 II pg -15031.5 0.05 0.03 1 28502.68 I pg -13155 -0.03 -0.05 1 29274.51 I pg -11890 0.00 -0.01 1 30306.79 I pg -10198 -0.03 -0.04 1 324.54 I pg -10169 0.03 0.02 1 339.17 I vis -10145 0.01 0.00 1 594.82 I pg -9726 0.02 0.02 1 597.83 I pg -9721 -0.02 -0.02 1 647.25: I vis -9640 -0.02 -0.02 1 996.25: I vis -9068 0.00 -0.01 1 31076.52 II pg -8936.5 0.04 0.03 1 438.60 I pg -8343 0.01 0.01 1 33541.65 I vis -4896 0.00 0.00 1 571.57 I vis -4847 0.02 0.02 1 582.54 I vis -4829 0.01 0.01 1 34242.672 I vis -3747 -0.004 -0.004 2 699.6515 I pe -2998 -0.0004 -0.0014 4 699.6525 I pe -2998 0.0006 -0.0004 4 710.6325 I pe -2980 -0.0015 -0.0024 4 710.6350 I pe -2980 0.0010 0.0001 4 735.6475 I pe -2939 -0.0012 -0.0022 4 735.6495 I pe -2939 0.0008 -0.0002 4 743.5780 I pe -2926 -0.0022 -0.0032 4 743.5815 I pe -2926 0.0013 0.0003 4 36528.7777 I pe 0 0.0000 -0.0013 5 538.540 I pe 16 0.000 -0.001 5 7180.688 II vis 1068.5 0.002 0.001 6 38269.447 I pg 2853 0.010 0.009 7 40100.398 I pe 5854 0.005 0.003 8 103.448 I pe 5859 0.005 0.003 8 133.344 I pe 5908 0.005 0.003 8 496.363 I pe 6503 0.005 0.003 8 41186.4006 I pe 7634 0.0024 0.0002 9 210.805 I pe 7674 0.002 0.000 10 213.853 I pe 7679 0.000 -0.003 10 276.697 I pe 7782 0.002 -0.001 10 2441618.3634 I pe 8382 0.0035 0.0012 11 679.371 I pe 8442 0.000 -0.003 11 900.538 II pe 8804.5 0.000 -0.003 11 951.484: I pe 8888 0.001 -0.001 11 951.486: I pe 8888 0.003 0.001 11 43012.4755 I pe 10627 0.0021 -0.0005 12 033.8307 I pe 10662 0.0032 0.0007 13 034.7460 II pe 10663.5 0.0034 0.0008 13 098.8043 II pe 10768.5 -0.0004 -0.0030 13 099.7228 I pe 10770 0.0029 0.0003 13 44868.4446 I pe 13669 0.0003 0.0000 14 45213.4622 II pe 14234.5 -0.0023 -0.0011 15 217.4266 I pe 14241 -0.0037 -0.0024 15 218.3475 II pe 14242.5 0.0021 0.0033 15 220.4784 I pe 14246 0.0024 -0.0012 15 576.484: II pe 14829.5 0.001 0.004 16 638.411 I pe 14931 0.001 0.004 16 46348.5782 I pe 16095 -0.0059 0.0005 17 359.5598 I pe 16113 -0.0064 0.0001 17 366.577 II pe 16124.5 -0.005 0.001 17 47040.4438 I pe 17229 -0.0111 -0.0015 18 043.4947 I pe 17234 -0.0108 -0.0012 18 062.4079 I pe 17265 -0.0111 -0.0015 18 063.3246 II pe 17266.5 -0.0096 0.0001 18 439.460: I pe 17883 -0.010 0.001 18 440.3766 II pe 17884.5 -0.0089 0.0025 18 455.3223 I pe 17909 -0.0110 0.0005 18 References to Table I: 1. Ashbrook, J.: 1951, Astron. J. 56, 54. 2. Ashbrook, J.: 1952, Astron. J. 57, 259. 3. Ashbrook, J.: 1953, Astron. J. 58, 171. 4. Svolopoulos, S.N.: 1957, Astron. J. 62, 330. 5. Chou, K.C.: 1959, Astron. J. 64, 468. 6. Robinson, L.J.: 1965, I.B.V.S. No. 119. 7. Oburka, O.: 1965, Bull. Astron. Inst. Czech. 16, 212. 8. Pohl, E., Kizilirmak, A.: 1970, I.B.V.S. No. 456. 9. Pohl, E., Kizilirmak, A.; 1972, I.B.V.S. No. 647. 10. Meyer, A.: 1972, I.B.V.S. No. 668. 11. Kizilirmak, A., Pohl, E.: 1974, I.B.V.S. No. 937. 12. Pohl, E., Kizilirmak, A.: 1977, I.B.V.S. No. 1358. 13. Faulkner, D.R., Kaitchuck, R.H.: 1983, I.B.V.S. No. 2321. 14. Rovithis, P., Rovithis-Livaniou, H.: 1982, I.B.V.S. No. 2094. 15. Rovithis, P., Rovithis-Livaniou, H.: 1983, I.B.V.S. No. 2424. 16. Pohl, E., Tunca, Z., Gulmen, O., Evren, 5.: 1985, I.B.V.S. No. 2793. 17. Pohl, E., Akan, M.C., Ibanoglu, C., Sezer, C., Gudur, N.: 1987, I.B.V.S. No. 3078. 18. This paper The times of minima obtained in 1985 (two primary and one secondary) and in 1987 (three primary and one secondary) implied a new sudden period change in the system. Therefore, the observations were continued in 1988 and two additional primary and one more secondary minima were also obtained. These minimum times, clearly confirming a sudden decrease in the period, and all the other ones from the literature are given in Table I. The O-C_1 and E (number of cycles) values were calculated with following light elements which are given by Chou (1959): Hel Min I JD = 2436528.7777 + 0.61011534d E (1) The O-C_1 residuals versus E values are shown in Figure I. As it is clearly seen in the figure, the first period change occurred between JD 2431500 and JD 2433500 (between 1945 and 1950). A new change in the period occurred recently, around 1981. These two occurrences of the period change divide the time axes into three parts for BX And. Therefore, the new light elements are separately calculated by weighted least squares method for these three parts as follows: Hel Min I JD = 2424064.773 + 0.61011214d E (2) +-24 +-49 for the first part (up to JD 2431500), Hel Min I JD = 2436528.7790 + 0.61011546d E (3) +-28 +-5 for the second part (between JD 2431500 and JD 2444700), Hel Min I JD = 2446359.5597 + 0.61011255d E (4) +-17 +-15 for the last part (after JD 2444700). The last ephemeris clearly shows a decrease in the period about 0.25 sec with respect to ephemeris (3). The O-C_2 values in Table I are calculated with the new light elements according to the time interval in which the observations were made. This work has been partly supported by Research Foundation of the Ege University with a project number 1987/066. O. GULMEN, N. GUDUR, C. SEZER, Z. EKER, V. KESKIN, B. KILINC, Ege University Observatory Campus PK, 21 Bornova, Izmir - Turkey References: Chou, K.C., 1959, Astron. J, 64, 468. [BIBCODE 1959AJ.....64..468C ] Soloviev, A., 1945, Astron. Circ. Acad. USSR. No. 44.