dcsetunits.pro

NRAO GBTIDL
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dcsetunits.pro

Last modification date:: Wed Sep 28 13:27:10 2016

dcsetunits

procedure dcsetunits, dc[, units], [tau=float], [ap_eff=float], [ret_tau=variable], [ret_ap_eff=variable], [ok=variable]

Set the units and convert the data to those units using the model described here.

This assumes that the units in the data container are in Ta, which is what they are immediately after the initial standard calibration (e.g. dofreqswitch). There is no attempt to look at the units field in the data container to see if this is appropriate or to undo any previous unit conversion prior to applying this conversion.

The recognized units and their associated scale factors are:

Ta - data are unchanged
Ta* - scale = exp(tau/sin(elevation))/0.99
Jy - scale = exp(tau/sin(elevation))/0.99 / (2.85*ap_eff)

The elevation is taken directly from the data container. Tau, the zenith opacity, may be supplied by the user. If not supplied, then the get_tau function is used, using the observed_frequency value from the data container. The aperture efficiency (ap_eff) can also be supplied by the user. If not supplied then the get_ap_eff function is used, using the observed_frequency from the data container.

Users are strongly encouraged to supply values for these keywords since the defaults are not very accurate.

Version: $Id$

Parameters

dc
in, required
data container The data container to use.

units
in, optional
string (def. 'Ta') The units to set, chosen from 'Ta','Ta*',and 'Jy'.

Keywords

tau
in, optional
float tau at zenith

ap_eff
in, optional
float aperture efficiency

ret_tau
out, optional
variable The tau actually used here.

ret_ap_eff
out, optional
variable The ap_eff actually used here.

ok
out, optional
variable This is 0 (false) if the units were unrecognized or tau and ap_eff were not between 0 and 1. In that case, the data are unchanged. Otherwise this is 1 (true).

Produced by IDLdoc 1.6 on Wed Sep 28 13:27:38 2016

Parameters
dc in, required data container	The data container to use.
units in, optional string (def. 'Ta')	The units to set, chosen from 'Ta','Ta*',and 'Jy'.

Keywords
tau in, optional float	tau at zenith
ap_eff in, optional float	aperture efficiency
ret_tau out, optional variable	The tau actually used here.
ret_ap_eff out, optional variable	The ap_eff actually used here.
ok out, optional variable	This is 0 (false) if the units were unrecognized or tau and ap_eff were not between 0 and 1. In that case, the data are unchanged. Otherwise this is 1 (true).