Up: Description of Associated Tasks
UV_GAIN computes a table of phase and/or amplitude gains from the self-
calibration of an observed UV table on a model UV table. The table of
self-calibrated visibilities is also output. The table of gain can then
be applied to another UV table through the UV_CAL task. This is useful
for instance to calibrate a line UV table from reference to the gain de-
rived from the self-calibration of the high signal-to-noise ratio con-
tinuum UV table of the same source. Only one channel of the observed UV
table can be calibrated at a time.
It is STRONGLY ADVISED to self-calibrate the phase first, then the am-
plitude using a longer smoothing time. You can choose between baseline-
based and antenna-based method to determine the gain.
- The baseline-based method output self-calibrated visibilities which are
identical to the modeled visibilities. This means that your model must
be correct to avoid bias.
- On the other hand, the antenna-based method takes the closure
relationships into account. You may thus iterate the self-calibration
using this method to try to converge. However, for this method to work,
decorrelation on the duration of each observed scan must be small to
avoid the loss of the amplitude closure relationships in the
averaging. In particular, the atmospheric phase contribution must be
stable on the scan duration.