./contrib
scalUtils.pro

Last modification date:

Wed Sep 28 13:27:15 2016

scalUtils is a collection of routines that return various quantities needed for calibration. Users will need to look over and maybe modify getTau and getFluxCalib before using any of the other scal or getVctr routines. Contact the contributor for additional details.

See also the scal User's Guide found in the documentation for scal.pro

Contributed By: Ron Maddalena, NRAO-GB

Routine Summary  6 routines

function getFluxCalib(src, freq, [coeffs=coeffs], [specindex=specindex])
Returns a vector of fluxes for a given vector of frequencies for standard calibrators.

function getApEff(elev, freq, [coeffs=vector])
Returns a vector of aperture efficiencies.

function getTau(freqs, [coeffs=coeffs])
Returns a vector of atmospheric zenith opacities.

function AirMass(elev)
Estimate the airmass as a function of elevation in degrees.

procedure Ta2Flux, tau=tau, ap_eff=ap_eff
Converts data in buffer 0 from Ta to Jy.

function quickTatm(freqs, TempK)
Calculates an estimate to Tatm from ground air temperature and frequencies.

Routine Details

getFluxCalib

function getFluxCalib(src, freq, [coeffs=coeffs], [specindex=specindex])

Returns a vector of fluxes for a given vector of frequencies for standard calibrators.

Can also be used to generate fluxes for non-standard calibrators.

Note: If coeffs is given, then src and specindex are ignored. If specindex is given, then src is ignored. src is only used if both specindex and coeffs is not used.

Recognized source names are: 3C48, 3C123, 3C147, 3C161, 3C218, 3C227, 3C249.1, VIRA, 3C286, 3C295, 3C309.1, 3C348, 3C353, NGC7027.

Calibrator coefficients are from the Ott et all or Peng list of calibrators.

Returns

a vector of fluxes at the given frequencies.

Version

$Id$

getApEff

function getApEff(elev, freq, [coeffs=vector])

Returns a vector of aperture efficiencies.

Note: You cannot supply a surface rms without also supplying a long wavelength efficiency.

Returns

vector of aperture efficiences at freq

Examples

 a = getApEff(45.0, freqs) ; returns the PTCS  model for ap_eff
 a = getApEff(45.0, freqs, coeffs=[0.69]) ; uses 184 microns but a long-wavelength eff of 69% 
 a = getApEff(45.0, freqs, coeffs=[0.73, 250]) ; uses 250 microns and a long-wavelength eff of 73%
 

getTau

function getTau(freqs, [coeffs=coeffs])

Returns a vector of atmospheric zenith opacities.

Returns

vector of atmospheric zenith opacities at freqs

Examples

 a = getTau(freqs, coeffs=[0.01]) ; an opacity that is constant with freq
 a = getTau(freqs, coeffs=[0.0234, 0.4567, 0.0045])
 

AirMass

function AirMass(elev)

Estimate the airmass as a function of elevation in degrees.

Returns

airmass

Ta2Flux

procedure Ta2Flux, tau=tau, ap_eff=ap_eff

Converts data in buffer 0 from Ta to Jy.

Keywords
tau in, required	atmospheric zenith opacity encoded as a vector. See the documentation for getTau for the format of the vector.
ap_eff in, required	aperture efficiency encoded as a vector. See the documentation for getApEff for the format of the vector.

quickTatm

function quickTatm(freqs, TempK)

Calculates an estimate to Tatm from ground air temperature and frequencies.

Only appropriate for freqs < 50 GHz.

The results of Maddalena & Johnson (2005, Bulletin of the American Astronomical Society, Vol. 37, p.1438). The rms uncertainty in my model is 3.5 K

Parameters
freqs in, required float	list of frequencies in MHz for which an opacity is needed
TempK in, required float	ground temperature in K