  The IAU Commission 4 Working Group on Standardizing Access to Ephemerides
recommends the use of the Spacecraft and Planet Kernel (SPK) format as a
standard format for the position ephemerides of planets and other natural solar
system bodies, and the use of the Planetary Constants Kernel (PCK) format for
the orientation of these bodies. It further recommends that other supporting
data be stored in a text PCK. These formats were developed for use by the SPICE
Toolkit by the Navigation and Ancillary Information Facility of NASA's Jet
Propulsion Laboratory (JPL). The CALCEPH library developed by the Institut de
mecanique celeste de calcul des ephemerides (IMCCE) is also able to make use of
these files. High accuracy ephemerides available in files conforming to the SPK
and PCK formats include: the Development Ephemerides (DE) from JPL, Integrateur
Numerique Planetaire de l'Observatoire de Paris (INPOP) from IMCCE, and the
Ephemerides Planets and the Moon (EPM), developed by the Institute for Applied
Astronomy (IAA). The bulk of this report is a description of the portion of PCK
and SPK formats required for these ephemerides. New SPK and PCK data types,
both called Type 20: Chebyshev (Velocity Only), have been added. Other changes
to the specification are (i) a new object identification number for coordinate
time ephemerides and (ii) a set of three new data types that use the TCB rather
than the TDB time scale for the ephemerides, but are otherwise identical to
their TDB versions.
