Report of the IAU Commission 4 Working Group on Standardizing Access to Ephemerides and File Format Specification

Abstract : The IAU Commission 4 Working Group on Standardizing Access to Ephemerides recommends the use of the Spacecraft and Planet Kernel (SPK) file format to provide a uniform format for the position ephemerides of planets and other natural solar system bodies, and the use of the binary Planetary Constants Kernel (PCK) format for the orientation of a body. It further recommends supporting data be stored in a text PCK. These formats are used by the SPICE system developed by the Jet Propulsion Laboratory. A new data type, Type 20: Chebyshev (Velocity Only) has been added. Other changes to the specification are new object identification numbers for coordinate time ephemerides, and a set of three new data types that uses the TCB rather than the TDB timescale.