Content-type: text/html Manpage of calmake


Section: User Commands (1)
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calmake - Create gcal file from observation of calibrator(s)  






CALMAKE is a MIRIAD task which creates a calibration dataset. it is needed because the calibration programs do not work directly on standard visibility files.

CALMAKE reads in dataset(s) of amplitude/phase calibration source(s), and creates a calibration dataset, called a ``gcal'' file. The data within the gcal file is taken from either the wide band correlation channels or some averaged value from the narrow band channels.  


Input visibility dataset(s) to be used for calibration. No default.
The output gain calibration dataset. No default.
The ``line'' parameter determines the channels that are to be processed from a uv data-set. The parameter value consists of a string followed by up to four numbers. Defaults are used for any missing trailing portion of the parameter value.

A uv data-set can have correlations from either (or both) a spectral or a wideband (continuum) correlator. Both the spectral and wideband correlators produce multiple correlations (channels). The string part of the line parameter is used to select the spectral or wideband channels. It may be one of:

  "channel"   Spectral channels.
  "wide"      Wideband (continuum) channels.
  "velocity"  Spectral channels, resampled at equal increments in
              velocity (using the radio definition). The resampling
              involves a weighted average of the spectral channels.
              This is useful if the source was not Doppler tracked
  "felocity"  Similar to "velocity", except that the parameters are
              given using the optical velocity definition.
Generally the default is "channel" if the data-set has spectral channel data, and "wide" otherwise.

The four numbers that accompany the string give:

  nchan, start, width, step

These four numbers specify which channels to select from the input dataset and how to combine them to produce the output channels that the Miriad task will work on.

nchan is the number of output channels produced. Generally it

        defaults to the number of input channels.

start is the first channel from input dataset that is to be used.

        It defaults to 1 (i.e. first channel).

width gives the number of input channels to average together to

        produce a single output channel. It defaults to 1.

step gives the increment between selected input channels. It

        defaults to the value of "width".

For "velocity" linetype, the start, width and step parameters are given in km/s. The output channels are centered on velocities: start, start+step, start+2*step, etc.

The `line' parameter interacts with the "select=window" selection for "channel" and "velocity"/"felocity" linetypes. See the help on select for more information.

For example:


selects 10 output channels, being input spectral channels 1 to 10. Similarly


selects 10 output channels, starting at input channel 8, and skipping every second input channel, whereas


selects 10 output channels, again starting at input channel 8, but each of the output channels consists of the average of two of the input channels. Finally


resamples the spectral data in velocity, to give 10 channels of width 1 km/s. The channels are centered at -10.0,-9.0,-8.0, etc, km/s. Default: ``wide,2,1,1,1'', i.e. the digital wideband data. Note that the number of channels MUST be 2.

This keyword selects the subset of the visibility data to be processed. There are a number of subcommands, which may be abbreviated. Each may be prefixed with a plus or minus sign to indicate using or discarding the selected data. Many subcommands can be given (separate them by commas). Examples:

See also documentation for subroutine selprobe(), which may very well differ slightly from this document.

Subcommands include:

Select data between times t1 and t2 (UT). Times are in the format:
Various abbreviations are possible. If no date part is given, then the time matchs all data (regardless of its date) for the given time of day. e.g. time(03OCT30:05:41:08,03OCT30:05:43:09)

Select all baselines pairs formed between first and second list of antennas. The second list is optional and defaults to all antennas.

Select visibilities with uv radius between uvmin and uvmax (in kilo wavelenghts). If only one value is given, uvmin is taken as zero.

Select visibilities with uv radius between uvmin and uvmax (in nanoseconds). If only one value is given, uvmin is taken as zero.

Select visibilities numbered n1 to n2 inclusive.

Select every inc'th visibility.

Select visibilities whose RA is in the range r1 to r2. RAs are given in the format
Various abbreviations are possible.

Select visibilites whose DEC is in the range d1 to d2. Declinations are given in the format
Various abbreviations are possible.

Selects on hour angle (values in decimal hours or hh:mm:ss)

Selects on LST (values in decimal hours or hh:mm:ss)

Selects on elevation (values in degrees)

Select visibilities for which the RA of the pointing center is offset from the main pointing center by between p1 and p2 arcseconds.

Select visibilities for which the DEC of the pointing center is offset from the main pointing center by between p1 and p2 arcseconds.

Select visibilities for which the DAZIM offset is between p1 and p2 arcseconds.

Select visibilities for which the DELEV offset is between p1 and p2 arcseconds.

Select visibilities with the rms pointing error in the range p1 to p2 arcseconds. If only one number is given, p1 is taken as 0.

Select visibilities on the basis of their polarization/Stokes parameter. p1,p2,p3,... can be selected from "i,q,u,v,xx,yy,xy,yx,rr,ll,rl,lr" Conversion between polarizations Stokes parameters (e.g. convert linears to Stokes) is not performed by this mechanism (see keyword stokes).

Select correlations from the particular source. Several sources can be given. An asterisk in the source name is treated as a wildcard. Note that the sourcename match is done IGNORING CASE.

Select based on the intent/purpose of the observation. Introduced in CARMA, where the letters B (bandpass), F (fluxcal), G (gaincal), P (polarization), R (radio pointing), S (science) and O (other) are used. Multiple letters from this set can be chooses. No wildcards allowed.

Select on seeing monitor rms path length (in microns). The UV variable used is smonrms for ATCA, rmspath for CARMA

Select correlations, where the sky frequency of the first correlation is in the range f1 to f2 (in GHz). If only a single frequency is given, then correlations are selected if the first correlation is within 1% of the given frequency. Note this selects the whole record. This may include several spectral-windows whose frequency is quite different from the first correlation in the first window.

Select any correlation, where the amplitude is between "amplo" and "amphi". If only one value is given, then "amphi" is assumed to be infinite.

Selects data that would be shadowed by an antenna of diameter "d" meters. If "d" is zero, then the actual diameter of the antennas (if known) is used. If some data is shadowed, it is advisable to use an antenna diameter value greater than the physical antenna size (e.g. 20% larger).

Select visibilities which have pulsar bin numbers in the range b1 to b2 inclusive. If b2 is omitted, just pulsar bin b1 is selected.

This is used with single dish observations, anbd selects based whether the "on" variable in the data is on (1) or off (0).

This is used with files that contain a mix of autocorrelations and crosscorrelations. This selects just the autocorrelation data.

Select by spectral window (IF band in AIPS terminology). See the help on window for more information.

The list of subcommands before and after the 'or' are "ored" together.

Default ??? Default: all data from the input datasets.
A logical, signalling if breakpoints are to be set automatically when the source name changes. Data before and after a breakpoint are then fit independently by separate polynomials in subsequent fitting programs. Also, data observed between the calibrators on either side of the breakpoint will be flagged bad in calapply if flagbad=true,true. Default: False (does not set breakpoints automatically).
List of sources and associated fluxes in Jy to be used for calibration. The format is name of the source, followed by its flux, and optionally more sources, e.g. fluxes=3c273,10.3,3c84,12.3,bllac,2.2 Currently no frequency dependency can be specified.
Name of the calibrators flux table file. If no name provided, the system default (MIRCAT/cals.fluxes) is taken. The user can also supply fluxes by hand (see keyword fluxes= above) in which case the flux table derived values are ignored. Note that reported frequencies of 0.0 means the flux was determined from interpolation accross different frequencies.




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Time: 18:35:38 GMT, July 05, 2011