1.2.1.0 ms.tofits

1.2.1 Convert a measurement set to a uvfits file
Description

This functions writes a UVFITS file that contains the data in the measurement set associated with this tool. The FITS file is always written in floating point format and the data is always stored in the primary array of the FITS file.

If the measurement set has been processed by many of the imaging tools, including imager and calibrator, it may contain additional data columns. You need to select which of these data columns will be written to the FITS file. The possible options are:

The parsing of these strings is case insensitive. If any other option is specified then the observed data will be written.

By default a single-source UVFITS file is written, but if the measurement set contains more than one field or if you set the multisource argument to True a multi-source UVFITS file will be written. Because of limitations in the UVFITS format you have to ensure that the data shape is fixed for all the data you intend to write to one FITS file. See the general description of this tool for how you can select data to meet this condition.

The combinespw argument is used to control whether data from different spectral windows will be written as different entries in the FITS FQ (frequency) table or combined as different IF’s within one entry in the FQ table. You should set this to True only if you know that the data from different spectral windows was observed simultaneously, and the data in the measurement set can be equally divided between all the spectral windows. Use of this switch is recommended for data to be processed in classic AIPS (if possible, e.g., standard dual IF observations).

The FITS GC (gain curve) and TY (system temperature) tables can be optionally written by setting the writesyscal argument to True. This is a rather WSRT-specific operation at the moment and may not work correctly for measurement sets from other telescopes.

The three parameters ’start’, ’nchan’, ’width’ are for channel averaging while outputing the data to the fits file. The default values of -1 will copy the channels of the input as is. ’start’ is input channel number that will be the first channel of the output. ’nchan’ is the number of channels wanted in the output data. ’width’ is the number of channels of the input data to make 1 channel of the output data. Hence (nchan*width+start) should not be larger than the number of channels in the original data.


Inputs
fitsfile	Name of the new uvfits file
	allowed:	string
	Default:
column	Data column to write, see above for options
	allowed:	string
	Default:	corrected
field	Field ids (0-based) or fieldnames to split out
	allowed:	any
	Default:	variant
spw	Spectral windows to split
	allowed:	any
	Default:	variant
nchan	number of channels in output, default of -1 implies all
	allowed:	int
	Default:	-1
start	Start channel in input data
	allowed:	int
	Default:	0
width	number of input channels to average
	allowed:	int
	Default:	1
baseline	Antenna names or Antenna indices to select
	allowed:	any
	Default:	variant
time	Limit data selected to be within a given time range. Syntax is the defined in the msselection link
	allowed:	string
	Default:
scan	Limit data selected on scan numbers. Syntax is the defined in the msselection link
	allowed:	any
	Default:	variant
uvrange	Limit data selected on uv distance. Syntax is the defined in the msselection link
	allowed:	any
	Default:	variant
taql	For the TAQL experts, flexible data selection using the TAQL syntax
	allowed:	string
	Default:
writesyscal	Write GC and TY tables
	allowed:	bool
	Default:	false
multisource	Write in multisource format
	allowed:	bool
	Default:	false
combinespw	Handle spectral window as IF
	allowed:	bool
	Default:	false
writestation	Write station name instead of antenna name
	allowed:	bool
	Default:	false

This example writes part (the first 2 fields and the third spectral window) of the corrected data to the fits file.

ms.tofits - Function