!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
!!! Copyright 2011 California Institute of Technology
!!!
!!! swap_sidebands.class
!!! 
!!! 2011-05-16 version 1.0 Initial release
!!! 2011-06-03 version 1.1 Copyright notice
!!!
!!! @swap_sidebands [ new_restf(MHz) ]
!!!
!!! Swaps signal and image sidebands.  Optionally moves reference channel and
!!! frequency.
!!!
!!! Use case: You have observed 12CO, 13CO, and C18O lines simultaneously with
!!! wideband receiver and spectrometer by doppler-tracking the 12CO frequency.
!!! The spectrometer was centered at the 12CO frequency in the signal sideband.
!!! Now you want scans *centered* at 13CO (or C18O) that was in the image
!!! sideband.
!!!
!!! file in ...
!!! file out ...
!!! find ...
!!! set variable spectro write
!!! set variable calibration write
!!! for i 1 to found
!!! get next
!!! @swap_sidebands 220398.6765
!!! write
!!! next
!!!
!!! C18O (J=2-1) 219560.3568 MHz
!!! 13CO (J=2-1) 220398.6765 MHz
!!! 12CO (J=2-1) 230538.0000 MHz

sic\let clight = 2.99792458e5 /new double ! Speed of light (km/s)

sic\let new_restf = image /new double
sic\let new_image = restf /new double
sic\let new_rchan = rchan /new real
sic\let new_fres = -fres /new real ! No change (topocentric!!!)
sic\let new_vres = -vres /new real

sic\if ("&1 ".ne." ") then
       sic\let new_restf = &1
sic\end if

sic\let new_image = (restf+image)-new_restf
sic\let new_rchan = rchan+(new_restf-image)*(1+doppler)/new_fres
sic\let new_vres = -clight*new_fres/((1+doppler)*new_restf)

sic\let restf = new_restf
sic\let image = new_image
sic\let rchan = new_rchan
sic\let fres = new_fres
sic\let vres = new_vres

sic\define real r4

sic\let r4 = tatms
sic\let tatms = tatmi
sic\let tatmi = r4

sic\let r4 = taus
sic\let taus = taui
sic\let taui = r4