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This version is identified by code_version_uvt_dopp =
code_version_uvt_v21 = 21:
- 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 mean Doppler factor, equal to
, is specified, where
is the Geocentric to selected system frame. It is stored in
the %gil%dopp variable.
- The source velocity within the selected system frame comes in
addition
- u,v coordinates are in a "normal" length, as measured in the
geocentric frame. The effective angular resolution is computed
from the apparent observing frequency, given by
 |
(2) |
- When merging two UV Tables with different Doppler factor, u,v
coordinates are NOT rescaled to a common Doppler factor. Instead a
mean Doppler factor is re-computed, and a warning of precision loss
given.
In conclusion, v2.1 has precise spectral axis definition, but lousy
angular resolution.
Next: Version 2.2: Local Doppler
Up: UV tables subversions and
Previous: Version 2.0: Historical Frequency
Contents
Gildas manager
2023-06-01