The Reconstructed Orbit file (*SC*ROS.ASC) contains the orbit position of the spacecraft. A single ASCII file is created for each observation and slew period. The numbers are Chebyshev Polynomial coefficients from which the orbit position can be calculated as a function of time. Details of the orbit files are provided in . For faster delivery, predicted orbit information is used if no reconstruction data are available. These are usually available within two weeks after an observation. The letter 'R' in the first column indicates that reconstructed orbit data are given, while a 'P' indicates that predicted data are given. The entries with letter 'P' are being replaced in the Reconstructed Orbit file as the reconstructed information comes in, and entries with 'P' should only occur in ODF data that are less than two weeks old.