COMMISSION 27 OF THE I. A. U. INFORMATION BULLETIN ON VARIABLE STARS Number 2085 Konkoly Observatory Budapest 1982 February 11 HU ISSN 0374-0676 PHOTOMETRIC OBSERVATIONS OF 1 PERSEI Radial velocity variations in 1 Per (HR 533, HD 11241, m_v= 5.52, Sp.T. B 1.5 V) have been suspected for 70 years. Estimates of the time scale of the variations have ranged from 15.6 days (Blaauw and van Albada, 1963) to "very short" (Beardsley, 1969). Light variations were first announced by Kurtz (1977). Kurtz suspected that 1 Per was an eclipsing binary, but he commented that the highest peak in the power spectrum of his observations was at a frequency of 3.01 cycles.day^-1 , or a period of 0.33 day. Because of the proximity of 1 Per to the Beta Cep instability strip, and because of my interest in the Beta Cep and related stars (Percy, 1980), I obtained photometric observations of 1 Per in 1980 and 1981. Subsequently, North et al.(1981) showed that 1 Per was an eclipsing binary with a period of 25.9359 days, and an eccentric orbit. Because the variations in 1 Per are now explained, and because I have found absolutely no evidence for intrinsic variations in 1 Per, I do not plan to observe this star further, and I am publishing my 1980 and 1981 observations at this time. The observations were made at the Kitt Peak National Observatory (Tucson, Arizona, U.S.A.) in November 1980 and 1981, using the #4 0.4 m telescope, a pulse-counting photometer, and a Stromgren b filter. The comparison star was HR 540, which was found by Kurtz (1977) to be constant. The observations are listed in Table I and shown in Figure 1. The phase has been calculated from the ephemeris of North et al (1981), namely: HJD (short minimum) = 2443562.853 + 25.9359 E The following conclusions can be drawn from these observations. 1. There is no intrinsic variability outside of eclipse (Delta b < 0.01m). 2. The light curve appears to be flat (Delta b < 0.01m) from phase 0.25 to 0.40 and from 0.45 to 0.60. Table I Photometric Observations (Delta b) of 1 Per--HR 540 ------------------------------------------------------------ HJD Phi Delta b HJD Phi Delta b 2444000+ 2444000+ ------------------------------------------------------------ 555.6764 0.280 -1.061 562.6653 0.549 -1.062 555.7243 0.282 -1.067 562.7708 0.553 -1.062 555.7944 0.284 -1.071 562.8729 0.557 -1.064 555.8917 0.288 -1.060 562.9313 0.560 -1.058 556.8590 0.325 -1.064 563.6736 0.588 -1.064 556.9354 0.328 -1.062 563.7375 0.591 -1.062 557.7813 0.361 -1.066 563.8472 0.595 -1.063 557.8861 0.365 -1.063 918.7280 0.278 -1.067 558.8271 0.401 -1.035 919.7083 0.316 -1.066 560.6632 0.472 -1.062 920.8326 0.359 -1.067 560.7431 0.475 -1.062 921.6840 0.392 -1.069 560.8576 0.480 -1.064 924.6889 0.508 -1.059 560.9604 0.484 -1.055 925.6715 0.546 -1.062 ------------------------------------------------------------ [FIGURE 1] Figure 1: Photometric observations (Delta b) of 1 Per relative to HR 540. 3. There is no significant change in brightness between 1980 and 1980 (Delta b < 0.01m). 4. Secondary minimum has begun by phase 0.401, and probably began at about phase 0.399. This information, when combined with Figure 3 of North et al (1981), suggests that the secondary minimum is symmetrical. I thank the Kitt Peak National Observatory for the use of the facilities there. I also thank the Natural Sciences and Engineering Research Council of Canada for financial support of this research. JOHN R. PERCY Department of Astronomy University of Toronto Toronto, Canada M5S 1A7 References: Beardsley, W.: 1969, Publ. Allegheny Obs. 8, 92. Blaauw, A., van Albada, T.S.: 1963, Astrophys. J. 137, 791. [BIBCODE 1963ApJ...137..791B ] Kurtz, D.W.: 1977, Publ. Astron. Soc. Pacific 89, 939. [BIBCODE 1977PASP...89..939K ] North, P., Rufener, F., Figer, A., Maurin, L.: 1981, IAU Inf. Bull. Variable Stars # 2036, 1. Percy, J.R.: 1980, Space Sci. Rev. 27, 313. [BIBCODE 1980SSRv...27..313P ]