摘要
UBV photometric observations of LQ And and EM Cep were made with 60 cm telescope at Beijing Astronomical Observatory from 1990 to 1992. Some results are briefly summarized as follows:(1) LQ And317 data sets have been obtained. HR9011 was used as the comparison star. Combining these data with some published VBV measurements of secured during 1983-1988, an improved period of light variation has been derived, and a new ephemeris for minimum light has been suggested:T min. light = HJD 2445621.5964 + 0.309418 × E.(2) EM Cep277 data sets have been obtained. HD208218 was used as the comparison star. With these data a minimum light time base been derived at HJD 2448912.0452. Combining this value with all published previously, an improved linear ephemeris has been derived with a rms of 0.01382:T min. light = HJD 2440134.7338 + 0.8061840 x EIt is of interest to note that there is also a possibility of decrease tendency of the period. We have derived an ephemeris by using a binomial fitting with a rms of 0.01155:
UBV photometric observations of LQ And and EM Cep were made with 60 cm telescope at Beijing Astronomical Observatory from 1990 to 1992. Some results are briefly summarized as follows:
(1) LQ And
317 data sets have been obtained. HR9011 was used as the comparison star. Combining these data with some published VBV measurements of secured during 1983-1988, an improved period of light variation has been derived, and a new ephemeris for minimum light has been suggested:
T min. light = HJD 2445621.5964 + 0.309418 × E.
(2) EM Cep
277 data sets have been obtained. HD208218 was used as the comparison star. With these data a minimum light time base been derived at HJD 2448912.0452. Combining this value with all published previously, an improved linear ephemeris has been derived with a rms of 0.01382:
T min. light = HJD 2440134.7338 + 0.8061840 x E
It is of interest to note that there is also a possibility of decrease tendency of the period. We have derived an ephemeris by using a binomial fitting with a rms of 0.01155:
T min. light = HJD 2440134.7368 + 0.8061861 × E -3.5679 × 10-10 × E
It means the dp / dt = -8.8514 ×10-10
It seems that the binomial fitting is better than the linear more or less. We expect to confirm it in further observations.
