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J.T. Armstrong, D. Mozurkewich (NRL), D.J. Hutter, J.A. Benson (USNO), T.E. Nordgren (USNO & Redlands Univ.), M. Karovska, D.D. Sasselov, M. Marengo, C. Papaliolios (CfA)
The Navy Prototype Optical Interferometer (NPOI) group has commissioned the first station on the outer part of the imaging array, i.e., beyond the three astrometric stations that have been the primary stations used so far. The new station, at pier W07 on the west arm, gives the NPOI a maximum baseline length of 64~m, or fringe spacings (B/\lambda) ranging from 2.7~mas at 850~nm wavelength to 1.8~mas at 550~nm. Cepheids observed previously with the 37~m baseline of the NPOI are among the first scientific targets of the new baseline. Long baseline interferometric measurements combined with disk bright distribution models derived from dynamic atmosphere models will allow accurate determinations of Cepheid angular diameters.