COMMISSION 27 OF THE I. A. U. INFORMATION BULLETIN ON VARIABLE STARS Number 3583 Konkoly Observatory Budapest 22 March 1991 HU ISSN 0374 - 0676 UBV PHOTOMETRY OF THE SYMBIOTIC STAR V1329 Cyg IN 1988-1990 The symbiotic star V1329 Cyg (HBV 475) was discovered by Kohoutek (1969). Since that time many astronomers have observed and made models for this star (Chochol and Vittone, 1986 and references listed by them). The star was observed photoelectrically from 26 Sep. 1988 to 29 Aug. 1990 with the 1.2 m Kryonerion telescope and a single channel photon counting photometer described by Dapergolas and Korakitis (1987). The photometer employs a high gain 9789QB phototube and conventional UBV filters. Its output is fed directly to a microcomputer enabling rapid data access. For the calibration of the photometer the UBV photoelectric equatorial sequences were used (Landolt, 1973). The period of observations covers ~75% of the phase of V1329 Cyg. The derived mean values are listed in Table I where n indicates the number of observations used for deriving the listed mean value. The phases were calculated using the linear ephemeris 2424869.9d + 950.07d given by Grygar et al. (1979). The instrumental errors for U,B,V data are +-0.1 mag, +-0.03 mag and +-0.04 mag respectively for 1988 and 1990 and +-0.2 mag, +-0.05 mag and +-0.05 mag respectively for 1989. The calibration error is ~0.04 mag. The derived U magnitudes in Table I show an excess that permits us to suggest the presence of an early type star. This is also confirmed from the B-V colour index that corresponds to a star certainly earlier than M type. A characteristic feature of the photometric behavior of V1329 Cyg is the presence of fluctuations on the light curve (DeltaV=~1 mag). These fluctuations were also observed during the pre-flare and after the flare period (Taranova and Yudin, 1986) and confirm that V1329 Cyg is an eclipsing binary. Table I Date (JD) V B U n Phase 2447431.32 13.16 13.67 5 .747 2447433.27 13.12 13.75 13.3 3 .749 2447435.32 13.14 13.75 13.3 12 .751 2447446.26 13.16 13.76 13.0 2 .763 2447447.25 13.09 13.75 13.1 1 .764 2447448.32 13.13 13.74 13.2 6 .765 2447451.29 13.14 13.78 13.1 3 .768 2447453.28 13.13 13.74 13.2 3 .771 2447454.25 13.15 13.74 13.1 3 .772 2447742.43 14.16 14.78 14.2 5 .074 2447743.49 14.11 14.73 14.1 4 .075 2447745.48 14.10 14.63 14.1 4 .077 2448097.56 13.05 13.64 13.4 5 .448 2448099.52 13.05 13.58 13.3 4 .450 2448124.53 13.12 13.64 13.3 2 .476 2448131.34 13.13 13.66 13.4 4 .484 2448133.32 13.07 13.6 13.3 5 .486 A. DAPERGOLAS and E. KONTIZAS M. KONTIZAS National Observatory of Athens University of Athens Astronomical Institute Laboratory of Astrophysics P.O. Box 20048 Panepistimiopolis GR Athens 118-10, Greece GR Athens 151-71, Greece References: Chochol, D., Vittone, A.: 1986, Astrophys. Space Sci., 75, 237. [BIBCODE 1986Ap&SS.121..225C ] Dapergolas, A., Korakitis, R.: 1987, Publ. Nat. Obs. of Athens, Ser. II, No. 28. Grygar, J., Hric, L., Chochol, D. and Mammano, A.: 1979, Bull. Astron. Inst. Czechosl. 30, 308. [BIBCODE 1979BAICz..30..308G ] Kohoutek, L.: 1969, I.B.V.S., No. 384. Landolt, A.U.: 1973, Astron. J., 78, 959. [BIBCODE 1973AJ.....78..959L ] Taranova, O.G., Yudin, B.F.: 1986 Soviet Astronomy, 30, 93. [BIBCODE 1986SvA....30...93T ]