The following example changes the RA phase centre by 10 seconds of time and also corrects a delay error of -3 ns on antenna 2 (by adding a phase gradient across the band). uvedit has the option to turn off the recomputation of u and v which might otherwise be done (options=nouv). This can be useful for say, entering a delay change (which does not need u and v to be recomputed) because Miriad does not compute u and v as accurately as the on-line ephemeris routines.
|vis=multi.uv||Input visibility dataset|
|source=0823-500||Specify source; unset means all|
|antpos||No change to antenna coordinates|
|ra=10||Move RA phase centre|
|dec||No change to DEC|
|time||No clock offset|
|delay=0,-3,0,0,0,0||Delay error on antenna 2|
|out=multi_corr.uv||Output visibility dataset|
|options||Do the works|
The task uvredo also `edits' a visibility dataset. Unlike uvedit, however, it only modifies ancillary data in the dataset that are derived from other information. For example, it can recompute the sky feed angle (``chi'') and velocity information.