Monthly report for October 2000 by Christian A. Hummel: Hummel attended the quarterly meeting of the NPOI team and presented his new dispersion correction algorithm. He also led a discussion of NPOI calibration issues. Hummel estimated positional uncertainties for narrow angle (i.e. relative) astrometry based on two experiments using the new dispersion algorithm to be about 3 mas for stars brighter than 2nd mag., and 14 mas to 20 mas for stars between V=4 and V=5. The three stars had about 25 scans each. Hummel attended the CHARA dedication on Mt Wilson. Hummel reduced, with help from N. Elias, about 11 nights of NPOI observations, of which three were regular stellar observations. He showed that Sigma Orionis, a triple system suggested by Deane Peterson, is observable with NPOI and could be a good candidate for imaging with the new six-station array.