Monthly report for April 2002 by Christian A. Hummel: Hummel reduced 12 nights of astrometric data, and investigated the problems causing the data quality to be poorer than that of the old 3-station configuration. For that purpose he wrote and updated several raw data analysis procedures. He also helped design test observations for the astrometry. Hummel modified his IDL based imaging routines to allow speedier processing of larger images. This is in preparation of a lab session prepared by Hummel on imaging with NPOI at this year's Michelson Summer School on Interferometry in June at the CfA.