UV analysis

In addition to the basic UV_MAP, the following tasks can also be used to perform analysis or operation on UV tables.

• UV_ASCAL
  Self-Calibrate a UV data set. It references the Phases and Amplitudes to a point source measured (almost) simultaneously.

• UV_CENTER
  Find the position of peak emission (for a presumably centro-symmetric brightness distribution) from UV data.

• UV_CLIP
  Clip UV data to flag bad points that escaped previous notice.

• UV_COMPRESS
  Compress UV data by spectral channel averaging.

• UV_EXTRACT
  Extract some spectral channels from UV table.

• UV_FIT
  Fit radial brightness distributions to UV data, and determine the center of symmetry.

• UV_FITC
  A less intelligent, but faster radial brightness distributions fitting to UV data. The source is assumed to be centered at the phase tracking center. Combination of two simple source models is allowed, if both are centro-symmetric around the same position.

• UV_FLAG
  Flag data in a UV table, following conventions similar to those used in CLIC.

• UV_MERGE
  Can merge two different UV tables.

• UV_SHIFT
  Displace phase center of a UV data set, and optionally rotate the axis.

• UV_SHORT
  Make a ``short spacings'' UV table from a single-dish map (30-m or other telescope). Can be merged later with another UV table. Caution: there are some limitations about single-dish map properties for this method to work.

• UV_SINGLE
  Make a ``short spacings'' UV table from a single-dish table (30-m or other telescope, as produced by CLASScommand GRID). No restriction of use. Can be merged later with another UV table.

• UV_STAT
  Make some ``statistics'' on a UV table. This task actually evaluates the beam size and noise level under various weighting and tapering combinations. It can be used prior to UV_MAP to get reasonable mapping parameters (specially UV_CELL and MAP_CELL).

• UV_ZERO
  Add zero spacing flux to a UV table (continuum or line).

• UV_SORT
  This task is a necessary step before some tasks can be used. It sorts UV data in an order appropriate for further gridding and mapping (negative and increasing V values) (UV order), or self-calibration and time averaging (TB order).