COMMISSION 27 OF THE I. A. U. INFORMATION BULLETIN ON VARIABLE STARS Number 2726 Konkoly Observatory Budapest 22 May 1985 HU ISSN 0374 - 0676 HD 167 971 - AN Of-TYPE ECLIPSING BINARY* HD 167971 (spectral type O8 Ibf ) has been reported by Leitherer et al. (1984) and Forbes (1984) to show photometric variations of ~0.3 magnitudes. In this note we present additional photometry enabling us to determine the period of variations. We obtained 42 photometric measurements of HD 167 971 during several observing periods between 1984 August and 1985 March. These observations were part of C. Sterken's "Long-Term Photometry of Variables" which is under way at ESO, La Silla. HD 167 971 was observed in the Stromgren-uvby system at the ESO 50-cm telescope and the Bochum 61-cm telescope, respectively. The results are listed in Table I. The photometric uncertainties are less than 0.03mag. As already noted previously, HD 167 971 shows variations in all observed passbands with the colours remaining constant. Notice that the Stromgren-y magnitude is nearly identical with Johnson-V for this spectral type. Throughout this note we assume y = V. Table I. Photometry of HD167 971 JD y b-y m1 c1 2445902.637 7.39 0.64 -0.19 -0.07 5902.648 7.39 0.62 -0.15 -0.09 5905.627 7.52 0.62 -0.16 -0.08 5909.646 7.37 0.62 -0.18 -0.06 5911.610 7.39 0.62 -0.17 -0.08 5914.754 7.36 0.63 -0.21 -0.05 5918.673 7.60 0.63 -0.19 -0.08 5924.698 7.37 0.63 -0.19 -0.07 5927.676 7.37 0.63 -0.18 -0.08 * Based on observations collected at the European Southern Observatory, La Silla, Chile Table I (cont.) JD y b-y m1 c1 5930.665 7.45 0.63 -0.18 -0.09 5933.641 7.63 0.64 -0.20 -0.07 5936.611 7.44 0.63 -0.19 -0.07 5939.665 7.36 0.63 -0.19 -0.08 5943.655 7.64 0.63 -0.19 -0.06 5950.578 7.48 0.63 -0.22 -0.08 5950.588 7.49 0.63 -0.22 -0.06 5950.596 7.47 0.62 -0.19 -0.10 5955.554 7.46 0.64 -0.22 -0.09 5966.523 7.43 0.63 -0.21 -0.09 5966.531 7.46 0.62 -0.21 -0.07 5971.554 7.43 0.63 -0.21 -0.08 5974.505 7.36 0.63 -0.22 -0.09 6135.882 7.44 0.62 -0.14 -0.06 6136.856 7.38 0.62 -0.15 -0.05 6137.863 7.58 0.63 -0.15 -0.05 6138.880 7.35 0.63 -0.16 -0.04 6139.871 7.47 0.63 -0.15 -0.04 6140.878 7.41 0.63 -0.16 -0.04 6141.870 7.35 0.63 -0.17 -0.03 6142.870 7.62 0.63 -0.15 -0.04 6144.886 7.45 0.63 -0.15 -0.04 6145.875 7.43 0.63 -0.17 -0.04 6146.863 7.37 0.63 -0.16 -0.06 6149.817 7.49 0.63 -0.13 -0.06 6149.904 7.46 0.63 -0.15 -0.05 6151.809 7.37 0.64 -0.16 -0.05 6152.831 7.63 0.63 -0.15 -0.05 6152.890 7.65 0.63 -0.15 -0.05 6152.894 7.65 0.63 -0.14 -0.05 6152.899 7.65 0.63 -0.14 -0.05 6152.904 7.65 0.63 -0.15 -0.05 6153.818 7.35 0.62 -0.15 -0.04 [FIGURE 1] Figure 1. Light curve of HD 167971 Combining the photometry of Table I and the values published by Leitherer et al. (1984) and Forbes (1984) leads to a total of 62 photometric data points of HD 167 971 over a period of nearly two years. We used these 62 measurements to investigate a possible periodicity of the variations following the method outlined by Stellingwerf (1978). The best-fit solution for the light curve of HD 167 971 is illustrated in Figure 1. HD167 971 proves to be a short-period eclipsing binary. We derive: Min. = 2445 555.0d + 1.6607d * E A less significant solution for the light curve of HD 167 971 would be twice the above period, namely 3.3212 days. In this case the light curve shows a secondary minimum about 0.05mag brighter than the primary minimum. We are not able to distinguish between the two periods with the existing photometry. Further photometry is needed to clarify this question. Acknowledgements: We are indebted to C. Sterken's "Long-Term Photometry of Variables" group who provided the Stromgren photometry of HD 167 971. This work was supported by the Deutsche Forschungsgemeinschaft (SFB 132). O. STAHL 1, D. FORBES 2, G. KLARE 1, C. LEITHERER 1, B. WOLF 1 and F.-J. ZICKGRAF 1 1 Landessternwarte Konigstuhl, D-6900 Heidelberg 1, F.R.G. 2 Department of Physics, Trent University, Peterborough, Ontario, Canada K9J 7B8 References: Forbes, D.: 1985, Inf. Bull. Var. Stars, No. 2605. Leitherer, C., Stahl, O., Zickgraf, F.-J., Klare, G., Wolf, B.: 1984, Inf. Bull. Var. Stars, No. 2539. Stellingwerf, R.F.: 1978, Astrophys. J., 224, 953. [BIBCODE 1978ApJ...224..953S ]