Angular diameter measurements of 24 giant and supergiant stars from the Mark III optical interferometer

Preliminary stellar diameter measurements of 24 stars made with the Mark III optical interferometer are reported. The stellar diameters reported were obtained using 12.0 and 8.3 m baselines with a center wavelength of 674 nm and a bandwidth of 10 nm. The observed visibilities were normalized using observations of nine stars of small angular diameter. The calibrated visibilities and best-fit uniform disk models for 24 giant and supergiant stars of angular diameters 4 mas to 18 mas, with accuracies of order 0.5 mas are presented.