Z component of the JWST velocity vector, relative to the geocentric terrestrial reference frame, in meters/second, at the mid-point of the exposure in the J2000 (ECI) coordinate system, which is an Earth-centered inertial frame defined by the Earth's mean equator and equinox on 2000-Jan-01. Science Data Processing code (SDP) obtains this from the observatory ephemeris data. Science Data Processing code (SDP) reads this from the observatory ephemeris data.
| Attribute | Value |
|---|---|
| data type | float |
| enumerated Values | not defined |
| units | m/s |
| example | |
| default value | |
| special processing | VALUE_REQUIRED |
| source | Science Data Processing (SDP) |
| software source | |
| calculation | jwst_dz value from either DefEphemeris or PredictEphemeris tables where useAfter date is closest to the exposure's EXPMID time, converted from km/s to m/s. |
| DB destination | ['ScienceCommonExt.obsgeodz', 'GuideStarExt.obsgeodz'] |
| data type in DB | float |
| instrument | ALL |
| mode | All |
| product level | 1b |
| FITS hdu | SCI |
| FITS header section | Ephemeris |