COMMISSION 27 OF THE I. A. U. INFORMATION BULLETIN ON VARIABLE STARS Number 2632 Konkoly Observatory Budapest 26 November 1984 HU ISSN 0374 - 0676 DISCOVERY THAT HR 454 IS A VARIABLE STAR HR 454 was included in a list of twenty bright suspected variables (Hall, 1983) after Bidelman (1983) reported observing strong Ca II emission and therefore suspecting it may be an RS CVn-type variable. According to the Yale Bright Star Catalogue the spectral type is gK1 and the apparent magnitude is V = 5.92m. Altogether eight different observatories made photoelectric observations, mostly in V, on 107 nights between October 20-21, 1983 and March 23- 24, 1984. The comparison star was 51 Andromedae, which is less than 20 arcminutes from HR 454 and differs less than 0.1m in B-V color index. The nightly mean differential magnitudes, corrected for differential atmospheric extinction and transformed differentially to the UBV system have been sent to the I.A.U. Commission 27 Archive for Unpublished Observations of Variable Stars (Breger 1982), where they are available as file no. 136 (Boyd) and file no. 54 (the others). The data in file no.136 were not corrected for dead time, because the dead time parameter had not yet been determined accurately. That my be a problem in this particular case because the comparison star is so bright (V = 3.6m) and the magnitude difference between it and HR 454 is so large ( DeltaV = 2.4m). The nightly means in V are plotted in Figure 1. The magnitudes in file no. 136, appeared systematically 0.05m brighter than the magnitudes in file no. 54 at corresponding times, we presume because of the above-mentioned dead-time problem. Therefore they have been plotted 0.05m fainter. In Figure 1 we see immediately that HR 454 is difficult to describe. Four minima are apparent (at JD 2445640, at 2445706, at 2445742, and at 2445782 or letter) but the intervals between are definitely not equal. Moreover, there appears to be a secular brightening, at a rate of approximately 0.045m/100 days. [FIGURE 1] Figure 1 Our light curve of HR 454 in V, with 51 And as the comparison star. The total range seen in 0.09m, but no simple periodicity is evident. Each symbol is a nightly mean, with a distinction made if the uncertainty is less than (+) or greater than (.) +- 0.010m. Table I ----------------------------------------------- Observers Providing Photometry of HR 454 Observer Observatory Aperture Nights ----------------------------------------------- Barksdale Barksdale 14-inch 18 Boyd Fairborn West 10-inch 38 Chang Riverdale 10-inch 3 Ingvarsson Tjorn Island 14-inch 28 Persinger E.T.S.U. 8-inch 6 Stelzer Stelzer 14-inch 1 Wasson Sunset Hills 8-inch 11 Ziegler Gila 11-inch 2 We plan to continue photometry of this interesting bright variable, to see if there is a periodicity in the variation and to see if the secular brightening continues. WILLIAM S. BARKSDALE, Jr. 633 Balmoral Road Winter Park, Florida 32789 LOUIS J. BOYD and RUSSELL M. GENET Fairborn Observatory 629 North 30th Street Phoenix, Arizona 85008 SANDY CHANG Riverdale Observatory 3249 Kingsbridge Avenue Bronx, New York 10463 DOUGLAS S. HALL Dyer Observatory Vanderbilt University Nashville, Tennessee 37235 STIG I. INGVARSSON Tjorn Island Astronomical Observatory Glashed 302 S-440 60 Skarhamn Sweden WILLIAM T. PERSINGER and HARRY D. POWELL Physics Department Eastern Tennessee State University Johnson City, Tennessee 37614 HAROLD J. STELZER 1223 Ashland Avenue River Forest, Illinois 60305 NORMAN F. WASSON Sunset Hills Observatory 15870 Del Prado Drive Hacienda Heights, California 91745 KENNETH W. ZIEGLER Gila Observatory P.O. Box 362 Claypool, Arizona 85532 References: Bidelman, W. P. 1983, I.A.U. Circ. No. 3765. [BIBCODE 1983IAUC.3765....3B ] Breger, M. 1982, I.B.V.S. No. 2246. Hall, D. S. 1983, I.A.P.P.P. Communication No. 13, 6. [BIBCODE 1983IAPPP..13....6H ] [DATAFILE 1] [DATAFILE 2]