5.1.2.0 sd.scantable.gain_el

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sd.scantable.gain_el - Function

5.1.2 Apply gain-elevation correction based on user-provided correction factors
Description

Return a scan after applying a gain-elevation correction. The correction can be made via either a polynomial or a table-based interpolation (and extrapolation if necessary). You specify polynomial coefficients, an ascii table or neither. If you specify neither, then a polynomial correction will be made with built in coefficients known for certain telescopes (an error will occur if the instrument is not known). The data and Tsys are *divided* by the scaling factors.

The polynomial coefficients to compute a gain-elevation correction should be given as that of a function of elevation in degrees. Contents of the ascii table specified by filename argument is correction factors as a function of time and elevation (in degree). The first row of the ascii file must give the column names and these MUST include columns ”ELEVATION” (degrees) and ”FACTOR” (multiply data by this) somewhere. The second row must give the data type of the column. Use ’R’ for Real and ’I’ for Integer. An example file would be (actual factors are arbitrary) :

TIME	ELEVATION	FACTOR
R	R	R
0.1	0	0.8
0.2	20	0.85
0.3	40	0.9
0.4	60	0.85
0.5	80	0.8
0.6	90	0.75

The interpolation method can be specified by method argument. Valid options are ’nearest’, ’linear’ (default), ’cubic’, and ’spline’.

Arguments


Inputs
poly	Polynomial coefficients to comput a gain-elevation correction
	allowed:	float array
	Default:	None
filename	The name of an ascii file holding correction factors
	allowed:	string
	Default:	”
method	Interpolation method when correcting from a table
	allowed:	string
	Default:	’linear’
insitu	If False a new scantable is returned
	allowed:	bool
	Default:	None

Returns
scantable

Example

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