COMMISSION 27 OF THE I. A. U. INFORMATION BULLETIN ON VARIABLE STARS Number 3368 Konkoly Observatory Budapest 24 August 1989 HU ISSN 0374 - 0676 THE ELEMENTS OF THE BINARY SYSTEM 44i BOOTIS The eclipsing variable 44i Bootis is the fainter component of the visual binary ADS 9494. 44i Bootis belongs to W UMa type. The binary system 44i Bootis was introduced in the photometric observational program of the Bucharest telescope following the IAU indications (Dworak and Oblak, 1987). The observations of 44i Bootis were made at Bucharest Observatory during 1987 using the 50cm telescope and a photoelectric photometer housing an EMI 9502B photomultiplier. Observations were made in V and B filters. The star FK4 1395 was used as the comparison star. The mean light curves indicate a change in minima places of approximately 0.065p. A Wood program was applied for elements calculation making first a translation of the curve with 0.065p. As initial values of i, T_A, k, r_A the values from Mauder's (1972) work were used. The elements, calculated from V and B observations, are: V filter: i=64.26deg r_A=0.372 q=0.510 u=0.650 beta=0.250 e=0 r_B=0.240 a_A=0.387 a_B=0.248 L_A=0.855 omega=0 T_A=5250degK b_A=0.372 b_B=0.238 L_B=0.145 k=0.641 T_B=4460degK c_A=0.358 c_B=0.234 B filter: i=62.92deg r=0.362 q=0.510 u=0.800 beta=0.250 e=0 r_B=0.230 a_A=0.375 a_B=0.237 L_A=0.896 omega=0 T_A=5250degK b_A=0.362 b_B=0.229 L_B=0.104 k=0.632 T_B=4378degK c_A=0.349 c_B=0.224 [FIGURE 1] Figure 1 shows the mean observational points by dots and the theoretical values, obtained with Wood program, by curves. From our observations (Table I) we have calculated four minima and the (O-C) values using: I - Pohl's (1967), II - Duerbeck's (1975) and III - GC 1976 ephemeris: I Min I =2444366.52904+0.2678158d E II Min I =2439852.4903 +0.2678159d E III Min I =2439370.4222 +0.2678160d E Table I Date (O-C) (O-C) (O-C) Min sigma Filter Obs. 244 I II III 6973.3286 0.0145 0.0153 0.0119 II 0.0009 U Oprescu G. .3296 0.0155 0.0163 0.0129 II 0.0014 B " .3352 0.0210 0.0218 0.0184 II 0.0004 V " 6977.3550 0.0237 0.0245 0.0211 II 0.0009 U " .3510 0.0197 0.0205 0.0171 II 0.0009 B " .3557 0.0243 0.0252 0.0218 II 0.0012 V " 6984.3159 0.0214 0.0221 0.0188 II 0.0003 U " .3174 0.0229 0.0236 0.0203 II 0.0009 B ' .3236 0.0291 0.0298 0.0265 II 0.0010 V " 6986.3253 0.0221 0.0229 0.0196 I 0.0005 U Suran M. .3237 0.0205 0.0214 0.0181 I 0.0007 B " .3257 0.0224 0.0233 0.0200 I 0.0007 V " [FIGURE 2] Many authors have pointed out sudden period changes for this star. Using Duerbeck's (1975) ephemeris we obtained the (O-C) values for a lot of minima between 1975-1988. Figure 2 shows a period jump in 1977-1978. The value of this sudden change we estimate to be delta P = 1.63d*10^-6. For the observations after 1977 we suggest a new period: Min I = 2443604.5880+0.26781753d E [FIGURE 3] Using this new ephemeris we reconsidered the (O-C) values, for the same observations as in Figure 2, beginning with 1977. Figure 3 shows the new (O-C) aspect. A sudden change in period is possible again between 1986 and 1988. More minima observations are needed in the future in order to point out the possible period change exactly. GABRIELA OPRESCU MARIAN DORU SURAN NEDELIA POPESCU Center for Astronomy and Space Sciences 5 rue Cutitul de Argint, 7000 Bucharest ROMANIA References: Duerbeck, H. W., 1975, I.B.V.S., No. 1023 Dworak, T. Z., and Oblak, E., 1987, I.B.V.S., No. 2991 Mauder, H., 1972, Astr. Astrophys. 17, 1 [BIBCODE 1972A&A....17....1M ] Pohl, E., 1967, I.B.V.S., No. 209