X 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_dx 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.obsgeodx', 'GuideStarExt.obsgeodx'] |
data type in DB | float |
instrument | ALL |
mode | All |
product level | 1b |
FITS hdu | SCI |
FITS header section | Ephemeris |