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This version is identified by code_version_uvt_syst =
code_version_uvt_v22 = 22:
- the frequency given in the spectral axis is also the rest
frequency, in the source frame (at the source velocity in the
selected system frame)
- the spectral resolution is in that same source frame
- a time dependent Doppler factor, equal to
, is
specified, where
is the Geocentric to selected system frame.
- it is stored in an extra column in the UV Table. This column is
identified by code_uvt_topo. It can replace one of the 7
mandatory column when in place modification is requested.
- when Doppler variations are small, this column may be absent and
in such a case, must be replaced by the global Doppler factor %gil%dopp.
- The source velocity within the selected system frame comes in
addition
- u,v coordinates are in a "pseudo-normal" length, as measured in the
geocentric frame. The effective angular resolution is computed
from the apparent observing frequency, given by
 |
(3) |
- when merging two UV Tables with different Doppler factors, the
Doppler column must be propagated, or created from the mean Doppler
factors of each table.
- the UV Table header has an observatory section to store the
observatory coordinates required to evaluate the Doppler factors.
Time and Date are already in the 7 mandatory uv columns.
In conclusion, v2.2 has precise spectral axis definition and precise
angular resolution.
Next: The new layout
Up: UV tables subversions and
Previous: Version 2.1: Global Doppler
Contents
Gildas manager
2023-06-01