COMMISSION 27 OF THE I. A. U. INFORMATION BULLETIN ON VARIABLE STARS Number 1024 Konkoly Observatory Budapest 1975 July 29 H beta-PHOTOMETRY OF HR 8024 AND HR 8102 HR 8012 (1900 : alpha=21h6.2m; delta=-14d53') was classified by Cowley et al. (1969) as a suspected delta Del-type variable. In order to investigate the possible variability of this star, it was observed extensively at the Mt. John University Observatory, Lake Tekapo, N.Z. in 1972 and at the Kitt Peak National Observatory in 1973 on the uvby system. Because of the close proximity of this star to HR 8024 (alpha = 20h53.2m; delta = -14d52'; F0 IV), the latter was also included on our observing program. Both stars are now identified as short period variables with amplitudes of the order of 0.1m and periods less than 3 hours according to our preliminary reductions. Extensive uvby analyses of these stars are presently being pursued. Photoelectric H_beta observations of these stars were collected on September 4, 1973 using the No. 4 40-cm telescope of Kitt Peak National Observatory. A 1P21 photomultiplier tube and H_beta filters nos. 493 and 494 were used in this investigation. SAO 169013 (1950: alpha =20h54m9; delta = -16d13.5'; A3) was used as a comparison star. The observations were obtained according to the following routine. Three 10-second integrations were obtained for each narrow- and wide-band filter and two 10-second integrations of background were recorded with each filter. The H_beta index thus obtained was put on the standard system using 10 A/F standards from Crawford and Mander (1966). For the variables the probable error for one beta -index is +-0.003m. The mean H_beta index computed for SAO 164013 is 2.855 +-0.002. Table 1 gives the observational data on the standard H_beta system for both stars. The first column lists the U.T. of observation and columns 2 and 3 give the H_beta indices for HR 8024 and HR 8102, respectively. The H_beta indices show peak-to-peak scatters of 0.015m for HR 8024 and 0.020m for HR 8102 and thus there are no H_beta index variations comparable to those observed in uvby photometry. No periodic variations were noticed during the whole observing run which lasted nearly two pulsation cycles. Average beta - indices of 2.799 +- 0.003 and 2.757 +- 0.004 were derived for HR 8024 and HR 8102, respectively. For A/F stars the beta index may be a more reliable and useful temperature indicator than is the (b-y) index. Our results suggest that there may be no large temperature variations for these stars during the pulsational cycles or that the stars could have been quiescent at the time of observation. At the present time, the former conclusion seems more likely. The absolute visual magnitudes of these stars were computed using the calibrations given by Crawford (1975) and have yielded M_v = + 1.85 for each of these stars. The absolute visual magnitudes thus derived and the preliminary periods identifies these stars as members of the normal delta Scuti group according to the classification given by Dworak and Zieba (1975). GOPAL C. KILAMBI Flower and Cook Observatory University of Pennsylvania Philadelphia, PA. 19174. U.S.A. References: Cowley, A., Cowley, C:, Jaschek, M. and Jaschek, C., 1969, A.J. 74, 375. [BIBCODE 1969AJ.....74..375C ] Crawford, D.L. 1975, Dudley Observatory Reports no. 9, 17. [BIBCODE 1975mpth.conf...17C ] Crawford, D.L. and Mander, J. 1966, A.J. 71, 114. [BIBCODE 1966AJ.....71..114C ] Dworak, T.Z. and Zieba, S. 1975, IBVS no. 1005. Table I. H_beta OBSERVATIONS OF HR 8024 AND HR 8102 ------------------------------------------------------ U.T.(non-hel.) HR 8024 HR 8102 ------------------------------------------------------ 1973Sept.4. 01h51m 2.805 56 2.776 02 08 2.814 12 2.760 16 2.798 20 2.764 28 2.800 30 2.747 35 2.817 43 2.749 52 2.816 57 2.775 03 01 2.800 04 2.758 14 2.804 18 2.776 21 2.800 25 2.752 34 2.801 37 2.771 41 2.782 45 2.764 57 2.809 04 01 2.754 05 2.782 09 2.762 17 2.800 21 2.752 25 2.795 30 2.749 37 2.803 41 2.753 46 2.792 51 2.761 05 00 2.815 03 2.743 08 2.786 12 2.754 19 2.797 23 2.751 27 2.821 32 2.754 44 2.787 49 2.752 05h53m 2.792 56 2.746 06 04 2.801 09 2.738 14 2.801 18 2.754 25 2.796 30 2.752 34 2.780 38 2.752 49 2.788 06 53 2.763 ------------------------------------------------------