COMMISSION 27 OF THE I. A. U. INFORMATION BULLETIN ON VARIABLE STARS Number 2474 Konkoly Observatory Budapest 8 February 1984 HU ISSN 0374-0676 NEW OBSERVATIONS OF CN ANDROMEDAE The eclipsing binary CN Andromedae, BD +39d0059, was observed on five nights at the Stephen F. Austin State University Observatory. The photometer, which utilizes a dry-ice cooled EMI 6256B photomultiplier, has been described elsewhere (Hibbs, 1980, Michaels, 1981, and Markworth and Michaels, 1982). The 707 observations in the natural B and V system of the telescope/photometer combination are presented in Figure 1. An additional 259 observations in the natural U system were also utilized to determine a total of eight new timings of primary minimum. [FIGURE 1] Figure 1 The individual differential magnitudes of CN And in the sense (variable-comparison). The eclipses during this epoch are rather asymmetric, with the egress branch of either eclipse rising faster than the descent of the ingress branch. Two methods of determination of the times of minimum were, therefore, attempted. Method 1 was the tracing paper method, where a free-hand curve drawn through the ingress branch was reflected upon the egress branch. The ingress branch was selected as the more symmetric, since evidence of excess light can be seen clearly at the maximum following primary minimum and probably affects the primary egress. Method 2 was a least squares fit of the bottom of the eclipse curve (i.e., before the inflexion points) by a parabola. The results are found in Table I. For the least squares fit, the quoted error was determined by standard error propagation techniques, which incorporate the individual errors for the best fit quadratic. Table I JD(2440000+) JD(2440000+) Filter Tracing Paper Least Squares V 5608.6999 5608.7001 +-.0047 B 5608.6999 5608.6987 +-.0048 U 5608.6982 +-.0067 V 5620.7300 5620.7299 +-.0041 B 5620.7291 5620.7282 +-.0027 U 5620.7335 +-.0067 V 5654.7426 5654.7441 +-.0018 B 5654.7387 5654.7423 +-.0028 A period study has been conducted using all available times of minimum. Table II lists the Heliocentric Julian Date of minimum, the (O-C) in days from our linear ephemeris, the type of minimum (primary or secondary), the method of observation, the weight given to the timings in the weighted least squares solution, and the reference. The timings of Lochel (1960) were found to be photographic observations (not photoelectric as identified by Seeds and Abernathy (1982)), and their weights reflect this change. The weighted least squares solution for the initial epoch and the period gives the ephemeris Hel JD_min = 2433570.48113 + 0.46279475d * E +-0.00361 +-0.00000016 Table II JD_min O-C_days Type Method Weight References 2433570.465 -.0161 pri pg 2 Lochel 4603.437 -.0019 pri pg 2 " 4653.406 -.0149 pri pg 2 " 4748.288 -.0057 pri pg 2 " 4779.283 -.0180 pri pg 2 " 5400.342 -.0296 pri pg 2 " 5868.244 -.0131 pri pg 2 " 6051.526 .0022 pri pg 2 " 6102.453 .0218 pri pg 2 " 6108.450 .0025 pri pg 2 " 6127.386 -.0361 pri pg 2 " 6399.533 -.0124 pri pg 2 " 6544.379 -.0212 pri pg 2 " 6848.466 .0097 pri pg 2 " 6899.366 .0022 pri pg 2 " 2441509.4930 -.0006 sec pe 6 Bozkurt, et al. 1509.4954 .0017 sec pe 6 1512.5044 .0025 pri pe 6 " 1512.5049 .0031 pri pe 6 " 1567.5746 .0002 pri pe 6 " 1567.5761 .0017 pri pe 6 " 1568.5012 .0012 pri pe 6 " 1568.5016 .0016 pri pe 6 " 1577.5278 .0033 sec pe 6 " 1577.5282 .0037 sec pe 6 " 1595.344 .0019 pri v 1 BBSAG 6, 1972 1664.282 -.0164 pri v 1 BBSAG 7, 1973 1930.401 -.0045 pri v 1 BBSAG 11,1973 1981.301 -.0119 pri v 1 BBSAG 12,1973 2369.352 -.0143 sec v 1 BBSAG 18,1974 2427.267 .0513 sec v I BBSAG 20,1975 2740.286 -.0103 pri v 1 BBSAG 24,1975 2993.450 .0050 pri v 1 BBSAG 29,1976 3069.357 .0136 pri v 1 BBSAG 32,1977 3431.277 .0281 pri v 1 BBSAG 35,1977 3432.462 .0561 sec v 1 " 3791.358 .0548 pri v 1 BBSAG 39,1978 4881.6483 .0007 pri pe 6 Seeds and Abernathy 4886.7382 -.0001 pri pe 6 " 4898.7716 .0006 pri pe 6 " 4908.2602 .0019 sec pe 6 Yulan and Qingyao 4899.2182 -.0156 pri pe 6 " 4934.1762 .0014 sec pe 6 4945.5136 .0003 pri pe 6 Seeds and Abernathy 5608.7001 .0019 pri pe 6 this paper 5608.6987 .0006 pri pe 6 " 5608.6982 .0000 pri pe 6 " 5620.7299 -.0009 pri pe 6 " 5620.7282 -.0026 pri pe 6 " 5620.7335 .0027 pri pe 6 " 5654.7441 -.0021 sec pe 6 " 5654.7423 -.0039 sec pe 6 " where the errors are standard errors. Parabolic, cubic, and differential corrections periodic/parabolic solutions were also attempted for this data using the program of Rafert (1977, 1982). The errors in the higher order terms were found to exceed the numerical values of the parameters in all cases, thus indicating a preference for the linear ephemeris. The clear evidence of excess light following primary minimum, and the disparity in the heights of the maxima are in stark contrast to the wellbehaved light curve of Seeds and Abernathy (1982) which were observed only a year previously. A complete study of CN And will be presented elsewhere. E.J. MICHAELS N.L. MARKWORTH J.B. RAFERT Stephen F. Austin State University Department of Physics Box 13044 Nacogdoches, Tx 75962 References: BBSAG 6 (1972), 7,11,12 (1973), 18 (1974), 20,24 (1975), 29 (1976), 32, 35 (1977), 39 (1978) Bozkurt, S., Ibanoglu, C., Gulmen, O., Gudur, N., 1976, I.B.V.S. No. 1087 Hibbs, M.F., 1980, Master`s Thesis, Stephen F. Austin State University Lochel., K., 1960, M.V.S. 457-468 Markworth, N.L. and Michaels, E.J., 1982, Publ.Astr.Soc. Pacific 94, 350 [BIBCODE 1982PASP...94..350M ] Michaels., E.J., 1981, Master's Thesis, Stephen F. Austin State University Rafert, J.B., 1977, Doctoral Dissertation, University of Florida Rafert, J.B., 1982, Publ.Astr.Soc. Pacific 94, 485 [BIBCODE 1982PASP...94..485R ] Seeds, M.A. and Abernathy, D.K. 1982, Pub.Astr.Soc.Pac, 94, 1001 [BIBCODE 1982PASP...94.1001S ] Yulan, Y. and Qingyao, L., 1982, I.B.V.S. No. 2202