COMMISSION 27 OF THE I. A. U. INFORMATION BULLETIN ON VARIABLE STARS Number 3020 Konkoly Observatory Budapest 5 May 1987 HU ISSN 0374-0676 PHOTOELECTRIC PHOTOMETRY OF RHO CASSIOPEIAE The star Rho Cassiopeiae (Rho Cas, HD 224014, = SAO 035879) was observed with the 0.6 meter Cassegrain telescope and a STARLIGHT-1 photon counting photometer at the University of Northern Iowa (UNI) Hillside Observatory using standard B and V filters. HD 223173 (=SAO 035763,K3II, V=5.51m, B-V=1.65) was used as the comparison star. Rho Cas is a supergiant (F8pIa) star (Percy, and Keith 1985). It has been a known variable for 86 years (Pickering, 1901), much of the time being confined to a brightness between 4.1m to 5.1m (Bailey, 1978). Between August 1945 and June 1947 the star decreased in brightness to 6.8m. (Gaposchkin, 1949) after which it recovered to 4.5m to 4.9m (Bailey, 1978). More recent reports, (January to June 1986) show the magnitude of Rho Cas varying less than 0.1m (Taylor, 1986). Since June 1986 observations at UNI in both blue and visual colors have indicated that Rho Cas has increased in brightness approximately 0.71m in the visual and 0.98m in the blue. The obtained differential magnitudes in the sense of Rho Cas - HD 223173 are given in Table I, which are also plotted in Figure 1 and Figure 2. Table I Photoelectric observations of Rho Cassiopeiae J.D.2446000+ Delta V Delta B-V 604.665 -0.5433 -0.1042 610.710 -0.5448 -0.1265 613.672 -0.5497 -0.1479 613.721 -0.5837 ------ 614.733 -0.5967 -0.0863 614.802 -0.5864 -0.1168 615.724 -0.5801 -0.1364 616.701 -0.5992 -0.0828 623.757 -0.6551 ------ 624.666 -0.6437 -0.0903 626.651 -0.6376 -0.0913 627.710 -0.6613 -0.0692 628.693 -0.6622 -0.0832 629.736 -0.6709 -0.0895 631.708 -0.6896 -0.0751 632.692 -0.6901 -0.0713 633.704 -0.6897 -0.0842 635.682 -0.6911 -0.0890 637.673 -0.7202 -0.0994 638.660 -0.7178 -0.0691 649.655 -0.7780 -0.1123 651.632 -0.8040 -0.0514 655.639 -0.8055 -0.0815 664.676 -0.8032 ------ 670.616 -0.8156 -0.0858 671.663 -0.8051 ------ 674.591 -0.8383 -0.0789 675.665 -0.8541 -0.0559 678.642 -0.8597 -0.0876 680.638 -0.8546 -0.1134 681.658 -0.8764 -0.0908 686.573 -0.9095 -0.1109 699.547 -0.9765 -0.0494 701.622 -0.9447 -0.1681 701.720 -0.9533 ------ 704.544 -0.9639 -0.1550 705.625 -0.9774 ------ 708.547 -0.9918 -0.1670 708.621 -0.9938 ------ 709.550 -0.9841 -0.1798 711.540 -0.9893 ------ 713.545 -0.9644 -0.2419 718.585 -1.0618 -0.2091 720.536 -1.0386 ------ 722.530 -1.0581 -0.1719 731.516 -1.0020 -0.2299 737.527 -1.0444 -0.2040 740.684 -1.0410 ------ 743.548 -1.0595 -0.2265 749.538 -1.0676 ------ 759.542 -1.0944 -0.2541 769.546 -1.1415 -0.2270 775.523 -1.1434 -0.2593 783.542 -1.1750 -0.2979 800.600 -1.2401 -0.3515 804.559 -1.2393 -0.3454 808.544 -1.2372 -0.3357 811.553 -1.2436 -0.3709 814.531 -1.2324 -0.3514 819.520 -1.2461 -0.3414 820.592 -1.2517 ------ 826.577 -1.2646 -0.3504 828.521 -1.2638 -0.3575 833.524 -1.2514 -0.3476 834.545 -1.2608 -0.3537 835.541 -1.2657 -0.3341 837.686 -1.2601 ------ 838.529 -1.2606 -0.3559 839.641 -1.2870 -0.3496 844.671 -1.2546 -0.3667 850.542 -1.2747 -0.3331 856.730 -1.2590 ------ 857.683 -1.3330 -0.2086 858.650 -1.2647 -0.3622 859.548 -1.2665 -0.3184 862.566 -1.2739 -0.3199 888.701 -1.1552 -0.2532 889.597 -1.2058 -0.2650 890.513 -1.1635 -0.2810 891.574 -1.1642 -0.3222 892.636 -1.1393 -0.3259 893.615 -1.2319 -0.2244 894.578 -1.1785 -0.2611 [FIGURE 1] [FIGURE 2] P. STEVEN LEIKER DARREL B. HOFF Hillside Observatory, University of Northern Iowa, Cedar Falls, Iowa 50613 USA References: Bailey, J. 1978, Rho Cassiopeiae, 1964-1975, Journal of the British Astronomical Association, Vol. 88, No. 4. p. 397-401 [BIBCODE 1978JBAA...88..397B ] Gaposchkin, S., 1949, Harvard College Observatory Bulletin, Number 919, p. 18-19 [BIBCODE 1949BHarO.919...18G ] Percy, J.R. and Keith, D., 1985, The Quasi-Cepheid Nature of Rho Cassiopeiae, in: Cepheids: Theory, and Observations, 1985, Barry F. Madore, p. 89-90 [BIBCODE 1985cto..conf...89P ] Pickering, E.C., 1901, Sixty-Four New Variable Stars, Harvard College Observatory, Circular Number 54. [BIBCODE 1901HarCi..54....1P ] Taylor, M., 1986, British Astronomical Association Variable Star Section extract from circular 65 Page a.