COMMISSION 27 OF THE I. A. U. INFORMATION BULLETIN ON VARIABLE STARS Number 3365 Konkoly Observatory Budapest 8 August 1989 HU ISSN 0374-0676 SEARCH FOR VARIABLE STARS IN A FIELD IN THE LMC The region 0.6deg x 0.9deg of the Large Magellanic Cloud centered near NGC 1854 (05h10m -68.9d) was surveyed for new variable stars. 7 exposures of the LMC made in 1967-72 (JD 2439849-2441385) with the 50-cm Maksutov reflector of the Chilean Station of Pulkova Observatory and 7 plates obtained in September-October 1988 with the 66-cm astrograph at the Mount Stromlo Observatory by A.A. Tokovinin and A. Loggins were used. The positive-negative ("Harvard") technique was used for the discovery of variable stars. The plates are of different quality and only 2-3 pairs could be selected for the comparison. The 16 stars not identified with known variables were suspected of variability. The identification charts for the suspected variables are given in Figure 1, north is up, the size of the squares is 3' if not indicated otherwise in the corner. Despite the use of the Harvard technique the variability is not certain at low amplitudes, such cases are marked with ?, e.g. VAR?-1. The Table contains coordinates for 1950.0, magnitude estimates and ranges of variation in the color system close to B. Photoelectric standards from Tifft et al. (1971, 1973) were used directly as comparison stars for the estimation of magnitudes. The moments of observation of some Chilean plates and of the 2 plates taken in Australia appear to be recorded with ~< 1 day error. These moments were corrected from the lightcurves of known short-period cepheids, e.g. TU Dor and SZ Dor. Most of the variable stars in this field are cepheids and the same applies to the newly discovered stars as well. Their periods must be in the 2-12 day range as estimated from the mean magnitudes. About 50 cepheids have been discovered previously in this field at the Harvard Observatory. The new stars have typically low amplitudes and low discovery probabilities. It is likely that no more than 50-75% of such stars have been discovered in the LMC. Further search for variable stars in LMC seems necessary. Table I. JD 24... VAR?-1 VAR-2 VAR-3 VAR?-4 VAR?-5 VAR?-6 VAR-7 VAR-8 R.A. 050616 050644 050716 050745 050802 050805 050820 050913 Dec. -6910.5 -6858.1 -6846.6 -6851.3 -6842.0 -6906.7 -6845.0 -6854.7 39849.9 16.40: 16.40 14.86 16.25 15.18 16.70 16.40 16.40 39852.75 16.58: 16.35 15.15 16.20 15.38 16.65 16.42 15.45 39948.6 16.82 16.35 14.85 15.96 15.40 16.80 16.25 15.18 40270.6 16.77 16.25 15.10 15.80 15.35 16.75 16.32 16.45 40272.55 16.58 15.93 15.18 15.80 15.15 16.70 16.35 15.70 40885.65 16.40 16.25 15.02 15.90 15.03 15.70: 15.75 16.23 41384.65 17.12 16.38 15.20 16.00 15.40 16.85 15.85 16.30 47410.125 - 15.50 15.13 15.83 15.12 - 15.70 15.98 47418.120 16.65 15.65 15.24 15.80 15.25 16.75 16.00 16.50 47423.172 16.82 16.20 15.20 15.90 15.13 16.40 16.45 16.18 47428.160 16.93: 16.12 15.30 15.95 14.90 16.63 15.67 15.16 47429.125 16.72 15.60 15.40 15.75 15.13 16.65 16.35 15.75 47441.169 - 15.58 15.12 16.00 15.16 - 16.60 15.12 47446.139 17.34 15.75 15.00 15.70 14.82 16.63 15.73 15.62 Max 16.4 15.5 14.85 15.7 14.8 15.7: 15.7 15.1 Min 17.3 16.4 15.4 16.25 15.4 16.85 16.6 16.5 VAR-9 VAR-10 VAR-11 VAR-12 VAR-13 VAR?-14 VAR?-15 VAR-16 R.A. 051006 051021 051058 051352 051419 051450 051453 051457 Dec. -6856.6 -6857.1 -6850.4 -6900.4 -6901.2 -6843.1 -6910.8 -6857.9 39849.9 16.00 16.30: 15.13 17.3: 15.97 15.85 15.10 16.90 39852.75 15.92 16.22 15.37 17.0: 15.63 16.05 15.15 16.95 39948.6 15.62 17.4:: 15.14 16.90: 15.65 15.10 15.20: 15.76 40270.6 15.16 16.25 15.60 16.50: 16.17 15.70 15.15 15.84 40272.55 15.12 17.20 15.78 16.95: 16.30: 15.65 15.08 16.87 40885.65 15.70: 17.42: 15.50 17.10: 15.64 15.85 15.35 16.75 41384.65 15.9:: 17.35: 15.26 15.50: 15.77 15.62 15.30 15.70 47410.125 15.23 17.05 15.57 - - - - - 47418.120 15.11 17.32: 15.25 16.52 15.87 15.20 15.45 16.67 47423.172 15.78 17.18: 15.70 16.95: 15.36 15.70 15.18 16.00 47428.160 15.72 17.15: 15.50 16.78: - - - - 47429.125 15.68 16.9: 15.44 16.82 - - - - 47441.169 15.43 16.73: 15.57 - - - - - 47446.139 15.84 16.37 15.42 - - - - - Max 15.1 16.2 15.1 15.5: 15.4 15.1 15.1 15.7 Min 16.0 17.4: 15.8 17.3: 16.3: 16.05 15.45 16.95 [FIGURE 1] N.E. KUROCHKIN, A.A. TOKOVININ Sternberg State Astronomical Institute, Moscow A. LOGGINS Yale University, Columbia, U.S.A. References: Tifft, W.G., Snell, Ch.M., 1971, M.N., 151, 365. [BIBCODE 1971MNRAS.151..365T ] Tifft, W.G., Connolly, L.P., 1973, M.N., 163, 93. [BIBCODE 1973MNRAS.163...93T ]