COMMISSION 27 OF THE I. A. U. INFORMATION BULLETIN ON VARIABLE STARS NUMBER 727 Konkoly Observatory Budapest 1972 October 17 PHOTOELECTRIC UBV OBSERVATIONS OF CEPHEID VARIABLE BE MONOCEROTIS The variable star BE Mon (BD+7d1394) was discovered by Hoffmeister (1). Soloview (2) observed that star visually by means of Nijland-Blashko method during the period Feb. 1935 - April 1936 with a 125 mm Zeiss refractor. Assuming RR Lyrae variability, he computed elements by the least squares method as: Max.Hel. J.D.=2427863.244d + 0.4210568d E His observations were published later (3). The next series of observations were made by Ahnert (4), reduced and discussed with the assumption of RR Lyrae type variability. However, in the next paper Ahnert (5) rediscussed his and the Soloview observations and classified the star as cepheid variable with elements: Max.Hel.J.D.=2427892.78d+2.705503d E The Cepheid type for BE Mon confirmed by spectral observations of Gotz and Wenzel (6) who observed a spectral range F3 - F9 for that star. Wisniewski observed the star photoelectrically during 1963-1965 on the UBV system. The data are given in Table 1 and plotted in Fig. 1, where phases were computed with formula: cycles + Phases =(J.D.-2438000)/P. The precision of photoelectric observations and 30 years time span between visual and photoelectric observations permit us to improve the period. From the Soloview observations we computed normal points with 0.03 phase interval. The new elements are: Max.Hel.J.D.=2438741.75d+2.705512d E Comparing the observed colours at min. with intrinsic colours of supergiant F9 from Johnson (7), we find the following excesses: U-V B-V BE Mon 2.15m 1.26m F9 I 1.12 0.62 Excess 1.03 0.64 which for R= A_v/E(B-V)=3.2 gives us 2.05m of absorption in visual region. Such absorption has an additional support from B. Lynds (8) Catalogue of Dark Nebulae, where near Equator for l=200d-210d dark nebulae are a common feature. N. BUCHANCOWA W. WISNIEWSKI Kliment Ochidskij Univ. Lunar and Planetary and Laboratory P. KUNCHEV The University of Dep. of Astronomy Arizona Univ. of Sofia Tucson, Arizona, Sofia, Bulgary U.S.A. References: (1) Hoffmeister C., A.N., 253, 195, 1934 [BIBCODE 1934AN....253..195H ] (2) Soloview A. Tadjik Circ. 20, 1936 (3) Soloview A. Variable Stars (Russian) 9, 2, 94, 1953 (4) Ahnert P. M.V.S. No, No. 400, 401, 1959 (5) Ahnert P. M.V.S. No 450, 1960 (6) Gotz W., Wenzel W. M.V.S. No 503-506, 1960 (7) Johnson H.L., A.Rev.Astr.Astrophys., 4, 193, 1966 [BIBCODE 1966ARA&A...4..193J ] (8) Lynds B., Ap.J.Supp. 7, 1, 1962 [BIBCODE 1962ApJS....7....1L ] [FIGURE 1] TABLE I Observations of BE Mon ------------------------------------------------------------------------------- 2438000+ V B-V U-B 2438000+ V B-V U-B ------------------------------------------------------------------------------- 370.859 10.58m 1.10m 0.80m 773.750 10.81m 1.23m 0.78m 370.888 10.53 1.08 0.79 773.844 10.76 1.26 0.82 370.900 10.52 1.07 0.78 784.630 10.76 1.18 0.87 370.916 10.50 1.07 0.77 784.663 10.74 1.19 475.641 10.74 1.26 784.709 10.69 1.17 0.86 475.650 10.74 1.28 784.749 10.67 1.12 0.78 703.905 10.24 1.02 784.795 10.58 1.11 0.90 703.919 10.24 1.04 784.855 10.49 1.10 0.94 725.926 10.43 1.04 792.622 10.88 1.25 0.84 725.935 10.43 1.08 792.649 10.84 1.29 0.90 729.883 10.76 1.23 792.726 10.79 1.23 0.70 741.739 10.20 1.03 0.75 792.758 10.76 1.18 0.92 741.753 10.19 1.04 0.68 809.625 10.35 1.00 0.75 741.765 10.21 1.04 0.73 809.661 10.36 1.03 0.70 741.787 10.21 1.04 0.64 809.740 10.37 1.07 0.74 741.798 10.22 1.04 0.64 810.584 10.72 1.27 741.812 10.22 1.02 0.68 810.632 10.72 1.26 0.92 741.823 10.22 1.01 0.69 810.658 10.73 1.26 0.91 741.845 10.21 1.04 0.64 810.693 10.74 1.25 741.860 10.23 0.99 0.67 810.762 10.76 1.25 741.874 10.23 1.00 0.68 811.626 10.79 1.25 0.90 741.905 10.23 1.06 0.63 811.720 10.77 1.20 742.756 10.54 1.28 811.756 10.73 1.18 742.815 10.64 811.853 10.61 1.06 744.746 10.32 1.01 812.618 10.45 1.12 0.76 744.835 10.43 1.06 812.665 10.49 1.12 771.759 10.25 1.02 812.680 10.50 1.15 771.809 10.36 1.01 -------------------------------------------------------------------------------