objectType TimeFrame

A TimeFrame SHALL include a time scale and reference position. It MAY also include a reference direction.

classDiagram

        class TimeFrame{
        coords:RefLocation refPosition
ivoa:string timescale
coords:RefLocation refDirection

        }
        TimeFrame --|> CoordFrame

link CoordFrame "../CoordFrame"

Members

name	type	mult	description
refPosition	RefLocation		The spatial location at which the coordinate is considered to have been taken. This model supports locations provided as either a standard reference position (e.g. GEOCENTER), or a coordinate specifying a custom location (e.g. long, lat, height).
timescale	ivoa:string		The time scale sets the reference frame. The value MUST be selected from the controlled vocabulary at the given URL.
refDirection	RefLocation	optional	The reference direction is needed if the time stamps are transformed to a time frame with a different reference position. In those situations, the solar system ephemeris also comes into play. See: FITS WCS Paper IV for details, but in short: The reference direction, presumably the direction to the thing being observed, is used in conjunction with the reference position and planetary ephemeris to determine the correction applied for the path length change. To be fully useful, one also needs to know the location at which the observation was made ( i.e. the observatory location), which is not considered to be Frame metadata.