function IPS_params, nagoya=Nagoya, cambridge=Cambridge, sandiego=SanDiego,	$
	freqmhz=FreqMHz, arcsec=ArcSec, sourcescale=SourceScale

@compile_opt.pro		; On error, return to caller

;+
; NAME:
;	IPS_params
; PURPOSE:
;	Sets parameters for calculating IPS velocities and g-levels
; CATEGORY:
;	Physics
; CALLING SEQUENCE:
;	R = IPS_params( /nagoya )
;	R = IPS_params( freqmhz=FreqMHz, arcsec=ArcSec, sourcescale=SourceScale)
; OPTIONAL INPUT PARAMETERS:
;	/nagoya			if set, returns [327 , 0.1, 1.0]
;	/cambridge		if set, returns [81.5, 0.3, 1.0]
;	/sandiego		if set, returns [73.8, 0.3, 1.0]
; OUTPUTS:
;	R			array[3]; type: float; default: [327, 0.1, 1.0] (Nagoya values)
;					R[0]: observing frequency in MHz
;					R[1]: source size (arcsec)
;					R[2]: source scale (multiplicative factor to be applied to source size)
; MODIFICATION HISTORY:
;	JUN-2000, Paul Hick (UCSD/CASS; pphick@ucsd.edu)
;-

if keyword_set(Nagoya) then begin
	FreqMHz = 327.		; Observing frequency (MHz)
	ArcSec  = 0.1		; Source size (arcsec)
endif else if keyword_set(Cambridge) then begin
	FreqMHz = 81.5
	ArcSec  = 0.3
endif else if keyword_set(SanDiego) then begin
	FreqMHz = 73.8
	ArcSec  = 0.3
endif else begin
	if n_elements(FreqMHz) eq 0 then FreqMHz = 327
	if n_elements(ArcSec ) eq 0 then ArcSec  = 0.1
endelse

if n_elements(SourceScale) eq 0 then SourceScale = 1.

return, [FreqMHz, ArcSec, SourceScale]  &  end