At the US Naval Observatory, raw data from the interferometer is first reduced through CONSTRICTOR, which is a stand-alone program which computes the visibilities and averages the data into 1 second intervals, i.e. the so-called point data. Averaged raw data from CONSTRICTOR can be found in /data/npoi/con, on gemini and in /home/constrictor on octans at the site. It is best to start up OYSTER in a directory owned by the user, and then to enter the full path to the data file when opening it. The path is stripped off by OYSTER when deriving output file names from the input file name so that all files are written into the local directory. Due to the size of the .con files, it is best not to make copies of them.
Averaged scan data from OYSTER is output into HDS files with the extension .cha. If you have a file with unknown history, the data might have been calibrated, or they might not. It is best to assume that they have to be calibrated, in which case one should remove any existing calibration before continuing. In order to find the right file for observations of a particular star, use the obsdates procedure (see section 8.15).