COMMISSION 27 OF THE I. A. U. INFORMATION BULLETIN ON VARIABLE STARS Number 3467 Konkoly Observatory Budapest 25 May 1990 HU ISSN 0374 - 0676 HD 93044: A NEW DELTA SCUTI VARIABLE? This note announces a possible new delta Scuti variable discovered in a photometric survey near the declination 40. The Cassegrain focus of the 0.6-m reflector at Xinglong Station of Beijing Observatory was used for this survey. The star light passes through the Johnson's V filter which consists of BG12(1mm) + GG13(4mm) filters and enters a photoelectric photometer in DC mode (Shi et al.,1987). The signal is then real-timely recorded by a micro-computer DATAMAX-8000, which can also display the observed light curve at any time and print out the observed data. On the night of April 8, 1990, we observed HD 93044 (SAO 043461), HD 92370 (SAO 043428) and HD 92221 (SAO 043420). With the high voltage of photoelectric amplifier being 2.7 kV, and the step of preamplifier high resistance being 10^7 ohm, and the diaphragm aperture being 1 mm (23"), these stars were observed in the order of sky, HD 93044, HD 92370 and HD 92221 for five hours. The integration time was 20, 30, 40 and 60 seconds, respectively. From the differential light curves presented in Figures 1a-b, it can be seen that the variation in brightness of HD 93044 is obvious. Because the uncertainty in the magnitude differences of the other two stars was as large as 0.032m (2 sigma), the observed variability needed to be confirmed. We continued to observe these stars on April 9, 1990. But the reference star HD 92221 which is the faintest (8.9m) in the group was abandoned and two other stars, HD 93457 (SAO 043475, 6.9m) and HD 93664 (SAO 043482, 7.8m) were added. The observing conditions were the same as those on the night of April 8. We performed six-hour differential observation in the order of sequence sky, HD 92370, HD 93044, HD 93664 and HD 93457, with the integration time of 20, 40, 30, 40 and 30 seconds, respectively. The light curves, no matter which of HD 93457 or HD 93664 was used as comparison, show the same periodic variations as presented in Figures 1c-d. The amplitude and period are about 0.09 and 2.0, respectively. The light curves of HD 93044 obtained on April 8 seem to have similar regularity. The observations April 9 were of high quality. Figure 1e shows the magnitude difference HD 93457 - HD 93664 which is constant within 0.001 mag. and gives sigma = 0.0049 mag. So, using these two stars as comparisons did not affect the basic feature of the light variation in HD 93044. [FIGURE 1a] Fig 1:a The light curve of HD93044 using HD92370 as comparison star [FIGURE 1b] Fig 1:b The light curve of HD93044 using HD92221 as comparison star [FIGURE 1c] Fig 1:c The light curve of HD93044 using HD93457 as comparison star [FIGURE 1d] Fig 1:d The light curve of HD93044 using HD93664 as comparison star [FIGURE 1e] Fig 1:e The differential curve of HD93457 - HD93664 In comparison with the eclipsing binaries, the light variation in HD 93044 is more complex. As the spectral class of HD 93044 is A7III, and its light variation is short-periodic and low-amplitude, we classify it tentatively as a delta Scuti variable. In Figure 1, the mv of the comparison stars, with some errors, are taken from the SAO Catalogue. This work was directed by Jiang Shi-yang, professor of Beijing Observatory. In analyzing the nature of the variable, professors Huang Lin, Shen Liang-zao and Zhang Ron-xian gave much help. Here we gratefully acknowledge their kindness. LI ZHI-PING Beijing Astronomical Observatory Academica Sinica Beijing, China TAN QING-QUAN Sichuan Normal College CAO MING Shaanxi Astronomical Observatory Reference Shi, C.M, Du, B.T. et al: 1987, Acta Astrophysica Sinica, 7, 230. [BIBCODE 1987AcApS...7..230S ]