Simultaneous Six-way Observations from the Navy Precision Optical Interferometer

Abstract

Abstract We measured the angular diameters of six stars using the six-element observing mode of the Navy Precision Optical Interferometer (NPOI) for the first time since the early 2000s. Four of the diameters ranged from 1.2 to 1.9 mas, while the two others were much smaller at approximately 0.5 mas to 0.7 mas, which are the two smallest angular diameters measured to date with the NPOI. There is a larger spread in the measurements than data obtained with three-, four-, or five-element modes, which can be attributed in part to the flux imbalance due to the combination of more than two siderostats in a single spectrograph, and also to crosstalk between multiple baselines related to nonlinearities in the fast-delay-line dither strokes. We plan to address this in the future by using the VISION beam combiner.