The angular diameter of X Cancri

Analysis of an occultation reappearance of the semiregular variable X Cancri observed with the 107-inch telescope of McDonald Observatory on 9 November 1971 by the laser group using slightly modified laser equipment. The problem of the effective temperature of this carbon star is discussed, and estimates near 2500 K are derived both from the occultation data and from an integration based on the multicolor photometry reported by Mendoza (1967). This figure is 300-400 K higher than Mendoza's calibration, and it is clear that unsolved problems remain in many areas connected with these stars.