Monthly report for June 1998 by Christian A. Hummel: CAH added code to the NPOI modeling software which simulates arbitrary observations of hierarchical stellar systems. The corresponding data files can be exported into FITS for mapping in AIPS. CAH installed the NPOI data reduction package OYSTER, written for PV-WAVE, on octans. CAH presented a talk at the IAU colloquium 170 in Victoria, "PRECISE STELLAR RADIAL VELOCITIES", on "Imaging and modeling of double stars with the Navy Prototype Optical Interferometer: a continuation of the Mark III double star program".