COMMISSION 27 OF THE I. A. U. INFORMATION BULLETIN ON VARIABLE STARS Number 3345 Konkoly Observatory Budapest 27 June 1989 HU ISSN 0374 - 0676 PHOTOELECTRIC PHOTOMETRY OF rho CASSIOPEIAE The peculiar variable star rho Cassiopeiae (HR 9045, HD 224014, SAO 035879) was observed by two observatories using photoelectric photometers. Observations covered the period of time from December 1987 through February 1989. This paper represents a follow-up of photometric data on the same star presented in earlier bulletins (Leiker, et al., 1988 and Leiker and Hoff, 1987). rho Cas is a supergiant (F8pIA) star (Percy & Keith, 1985). rho Cassiopeiae was discovered to be a variable in 1900 by Louise D. Wells (Pickering 1901). Much of the time this star was confined to a brightness between 4.1m and 5.1m (Bailey, 1978). Between August 1945 and June 1947 rho Cas decreased in brightness more than a magnitude (Gaposchkin, 1949). After it recovered from this minimum, rho Cas continued its irregular variation in brightness of 4.1m and 5.1m (Leiker 1987). rho Cas was observed by Leiker and Hoff at the University of Northern Iowa (UNI) Hillside Observatory from May 1988 until January 1989. A 0.4 meter Cassegrain telescope and a STARLIGHT-1 photon counting photometer with standard B and V filters was used. HR 9010 (HD 223173, SAO 35761, K3 II, V=5.51 m, B-V=1.65) was used as the comparison star. These delta magnitudes are not corrected for color or extinction. Standard deviation (sigma) was calculated in the usual manner. Table 1 lists the DeltaV and DeltaB magnitudes. Figure 1 displays the visual data obtained by both Leiker, Hoff, and Milton. Figure 2 is a graphical representation of the blue data presented in Table 1. Milton observed rho Cas from December 1987 to February 1989 using a 0.2 meter Schmidt-Cassegrain telescope with a pulse counting photoelectric photometer. HR 9010 was used as the comparison star. Table 2 lists V delta magnitudes corrected for color and extinction. Milton's data is also displayed in Figure 1. Standard deviation was calculated in the usual manner. Milton also observed tau Cassiopeiae (HR 9008, HD 223165, SAO 35763, K1 III, V=4.87 m) as a check star. The check star delta magnitudes are corrected only for extinction. [FIGURE 1] Figure 1. DeltaV magnitudes of rho Cas obtained by Leiker, Hoff, and Milton Table I. DeltaV and deltaB magnitudes of rho Cas obtained by Leiker and Hoff HJD V Mean sigma # HJD B Mean sigma # 2447306.652 -0.990 0.029 3 2447306.6629 -1.204 0.015 3 2447317.663 -0.963 0.007 3 2447317.6744 -1.208 0.005 3 2447318.648 -0.951 0.008 3 2447318.6605 -1.203 0.007 3 2447323.646 -0.902 0.043 3 2447323.6669 -1.246 0.014 3 2447323.707 -0.995 0.008 3 2447338.6670 -1.252 0.016 3 2447324.688 -0.958 0.067 3 2447359.6585 -1.320 0.006 3 2447338.654 -0.980 0.018 3 2447363.7012 -1.335 0.003 3 2447359.648 -1.017 0.034 3 2447384.6295 -1.380 0.018 3 2447363.691 -1.034 0.012 3 2447385.6315 -1.407 0.012 3 2447384.616 -1.079 0.009 3 2447389.6327 -1.394 0.003 3 2447385.619 -1.079 0.009 3 2447397.6708 -1.390 0.009 3 2447389.610 -1.079 0.005 3 2447401.7315 -1.380 0.021 3 2447397.658 -1.071 0.004 3 2447404.7234 -1.400 0.032 3 2447401.717 -1.066 0.002 3 2447445.6452 -1.280 0.028 3 2447404.711 -1.059 0.002 3 2447448.5911 -1.264 0.006 3 2447442.626 -1.022 0.031 2 2447465.5758 -1.251 0.007 3 2447445.634 -0.982 0.004 3 2447473.7037 -1.256 0.006 3 2447448.576 -0.964 0.007 3 2447479.5335 -1.244 0.001 3 2447465.566 -0.959 0.004 3 2447498.7143 -1.229 0.003 3 2447473.693 -0.958 0.012 3 2447479.521 -0.958 0.002 3 2447497.522 -0.945 0.010 3 2447498.702 -0.944 0.003 3 2447506.522 -0.944 0.008 3 2447553.545 -1.020 0.008 3 [FIGURE 2] Figure 2. DeltaB magnitudes of rho Cas obtained by Leiker and Hoff Table II. DeltaV magnitudes of rho Cas obtained by Milton HJD V Mean sigma # Check 2447141.831 -1.033 0.012 3 -0.703 2447185.723 -0.938 0.015 3 -0.665 2447193.654 -0.925 0.003 3 -0.688 2447206.666 -0.912 0.003 3 -0.666 2447222.665 -0.956 0.008 3 -0.700 2447352.845 -0.970 0.010 3 -0.679 2447365.787 -1.018 1 2447372.845 -1.028 0.013 3 -0.674 2447392.819 -1.037 0.001 3 -0.689 2447401.757 -1.033 0.006 3 -0.685 2447408.816 -1.017 0.006 3 -0.673 2447415.696 -1.022 0.007 3 -0.670 2447430.667 -1.007 0.003 3 -0.680 2447444.685 -0.936 0.005 3 -0.675 2447457.649 -0.909 0.004 3 -0.672 2447464.664 -0.912 0.003 3 -0.686 2447510.692 -0.884 0.009 3 -0.689 2447538.651 -0.927 0.042 3 -0.665 2447545.692 -0.973 0.008 3 -0.691 2447551.688 -0.969 0.008 3 -0.692 2447555.660 -0.985 0.002 3 2447562.668 -0.984 0.004 3 -0.690 2447582.675 -1.005 0.017 3 -0.661 This work was supported in part by a computer equipment grant from a Theodore Dunham, Jr. Grant of the Fund for Astrophysical Research. P. STEVEN LEIKER Hillside Observatory Department of Earth Science University of Northern Iowa Cedar Falls, Iowa 50614-0506 USA DARREL B. HOFF Harvard-Smithsonian Center for Astrophysics 60 Garden St. Cambridge, MA 02138 USA RUSSELL MILTON Klamath Observatory 94522 Highway 96 Somes Bar, CA 95568 USA References: Bailey, J. (1978). Rho Cassiopeiae, 1964-1975. Journal of the British Astronomical Association. 88, (4), 397-401. [BIBCODE 1978JBAA...88..397B ] Gaposchkin, S. (1949). Rho Cassiopeiae. Harvard College Observatory Bulletin Number 919, 18-19. [BIBCODE 1949BHarO.919...18G ] Leiker, P. S. and Hoff, D. B. (1987). Photoelectric photometry of Rho Cassiopeiae. Information Bulletin on Variable Stars. Number 3020. Leiker, P. S. (1987). A review of photometric research on rho Cassiopeiae including photoelectric observations obtained at the University of Northern Iowa. Unpublished Master's Thesis. University of Northern Iowa. Cedar Falls, Iowa, USA Leiker, P. S., Hoff, D. B., Nesbella, J., Gainer, M., Milton, R., & Pray, D. (1988). Photoelectric photometry of rho Cassiopeiae. Information Bulletin on Variable Stars. Number 3172. Percy, J. R., & Keith, D. W. (1985). The quasi-cepheid nature of Rho Cassiopeiae. Madore, B. F. Cepheids: Theory and Observations. University of Cambridge Press. [BIBCODE 1985cto..conf...89P ] Pickering, E. C. (1901). Sixty-four new variable stars. Harvard College Observatory Circular. Number 54. [BIBCODE 1901HarCi..54....1P ]