Basic Information on select

Key: select
	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). Subcommands include:

	  time(t1,t2)
	Select data between times t1 and t2 (UT). Times are in the format:
	  yymmmdd.fff
	or
	  yymmmdd:hh:mm:ss.s
	Various abbreviations are possible. If no date part is given, then
	the time matches all data (regardless of its date) for the given
	time of day. The year is given by just two digits. The year is
	assumed to be in the century 1940 to 2040.      

	  antennae(a1,a2,...)(b1,b2...)
	Select all baselines pairs formed between first and second list of
	antennas. The second list is optional and defaults to all antennas.

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

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

	  visibility(n1,n2)
	Select visibilities numbered n1 to n2 inclusive.

	  increment(inc)
	Select every inc'th visibility.

	  ra(r1,r2)
	Select visibilities whose RA is in the range r1 to r2. RAs are given
	in the format
	  hh:mm:ss
	or
	  hh.hhh
	Various abbreviations are possible.
	
	  dec(d1,d2)
	Select visibilites whose DEC is in the range d1 to d2. Declinations
	are given in the format
	  dd:mm:ss
	or
	  dd.ddd
	Various abbreviations are possible.

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

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

	  pointing(p1,p2)
	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.

	  seeing(p1,p2)
	Select visibilities with the rms seeing (pathlength) in the range 
        p1 to p2 microns. If only one number is given, p1 is taken as 0.
        The corresponding uv variable is called smonrms.

	  polarization(p1,p2,p3,...)
	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).

	  source(srcnam1,srcnam2,...)
	Select correlations from the particular source. Several sources
	can be given. An asterisk in the source name is treated as a
	wildcard.

	  purpose(p1,p2,...)
	Select correlations with the particular purpose (CARMA) or 
        calcode (ATCA). 
        Several values can be given.

	  frequency(f1,f2)
	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.

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

	  shadow(d)
	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).

	  ha(h1,h2)
	Select based on the hour angle of the data. h1 and h2 are the
	hour angle (in decimal hours).

	  elevation(e1,e2)
	Select data based on the elevation at which the data were observed.
	e1 and e2 give the elevation range in degrees.

	  lst(l1,l2)
	Select data based on the LST of the observation. l1 and l2 are the
	start and end LST values, and can be given in the form hh:mm:ss
	or in decimal hours.

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

	  on
	This is used with single dish observations, anbd selects based
	whether the "on" variable in the data is on!

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

	  window(w1,w2,...)
	Select by spectral window (IF band in AIPS terminology). See
	the help on window for more information.

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