2. A preliminary period analysis
We used the RVs reported by Campbell & Moore (1928) and Smalley et al. (1997) in a preliminary period analysis. ISDA (Irregularly Spaced Data Analysis; Pelt 1992) gives several possibilities to derive periods from irregularly spaced data. Three different methods gave consistently a period of 7.87 days. Note, that this period is quite short compared to the sampling rate of both the old and the data by Smalley et al. (1997). Since neither of these methods assumes anything about the shape of the phase diagram, it was further encouraging to note that the phase diagram for this period had the shape of an elliptical RV-curve with a sharp minimum (lasting about 0.2 in phase; the RV-curve with this period has km s-1 and ; the typical measurement has km s-1, consistent with the above considerations about the measurement errors). Thus, we decided to observe Crt in an observing run at the Bulgarian National Astronomical Observatory, Rozhen, in May 1997.
© European Southern Observatory (ESO) 1997
Online publication: March 26, 1998