Space Telescope Science Institute  3.5 Equinox for Coordinates [Equinox] 3.7 Radial Velocity or Redshift [RV_ or _Z]

3.6 Coordinate Reference Frame [Reference_Frame]

This keyword replaces Coordinate_Source starting with Cycle 14 Calibration and all Cycle 15 programs. Select one of the following Reference_Frame values for each target.

ICRS

To be used if the coordinate reference frame is tied to the International Celestial Reference System (ICRS). Catalogs tied to the ICRS include: HST Guide Star Catalog 2 (GSC2), Hipparcos Catalog and the Tycho-2 Catalog.

Other

To be used if the coordinates are notICRS.

3.5 Equinox for Coordinates [Equinox] 3.7 Radial Velocity or Redshift [RV_ or _Z]
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