Monthly report for October 1999 by Christian A. Hummel: Hummel attended the quarterly meeting of the NPOI group in Flagstaff. Hummel began a more systematic investigation into the dispersion correction and related issues by extending and making use of raw data analysis procedures written in IDL. He has assembled the raw data files of 7 nights for a comparative analysis. Tools like power spectra computation, large data set plot graphical user interfaces, and image displays have been added to the OYSTER software. Hummel helped with the APD fiber preparation and dewar installation.