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Basic Information on tmcal
Purpose: Gain/phase/polarization calibration for SMA data.
tmcal is a MIRIAD task which determines calibration corrections
(both antenna gains and instrumental polarisation characteristics).
Input visibility data file. No default. The visibility data
must be in time order.
Standard uv selection. Default is all data.
Standard line-type specification. Multiple channels can be given.
Generally it is better to give multiple channels, rather than
averaging them into a `channel-0'. The default is all the channel
data (or all the wide data, if there is no channel data).
The values of the I,Q,U Stokes parameters. If no values are
given, and it is a source known to tmcal, tmcal uses its known
flux as the default. If tmcal does not know the source, the
flux is determined by assuming that the rms gain amplitude is 1.
For a planet, the values are interpreted as brightness temperature
in Kelvin (planets are assumed to be unpolarised). Otherwise the values
are assumed to be in Janskys.
If the option `qusolve' is used, the given fluxes for Q and U are
used as the initial estimates.
The reference antenna. Default is 1. The reference antenna needs to be
present throughout the observation, and so needs to be chosen with some
care. Any solution intervals where the reference antenna is missing are
The minimum number of antenna that must be present before a
solution is attempted. Default is 2.
This gives the solution interval, in minutes. Antenna gains are assumed
to be constant over the solution interval.
Error tolerance. The default is 0.001, which should be adequate.
These options determine what TMCAL solves for. Several options
can be given,separated by commas.
nopass Do not apply any passband calibration.
qusolve Solve for Q and U fluxes. Good parallactic
angle coverage is required for this.
twoleak Solve for a "two part" leakage solution,
onegain Solve for a single antenna gain, which is assumed to be
independent of polarisation. When time-multiplexing of a single
feed is used to measure two states (e.g. R and L), then it should
be accurate to assume the antenna gains to R and L are the same.
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