VLBI observations are unique in that we don't (can't) steer the sky 
frequency according to the rest frequency and object velocity.  Instead,
the sky frequency is held to what is dialed in manually at the receiver.
To get the radial velocities right in the CLASS spectra, we put FEORGA 
in a mode where it modifies the object velocity so that if it could 
tune the receiver, it would tune it to the sky frequency that we're using
for VLBI.

Actually, there are two frequencies planned for the April 2002 VLBI:
147 GHz (which is very close to the CS(3-2) rest frequency) and the rest 
frequency of the SiO(3-2)v1 line.  There's a script can be used to put 
FEORGA in this mode or put it back into the normal mode.  Type 

    @TEL$OBS:VLBI_FREQ CS
or  @TEL$OBS:VLBI_FREQ SIO
or  @TEL$OBS:VLBI_FREQ NONE

In addition to specifying the VLBI sky frequency, the script automatically
executes the appropriate LINE command.

If you forget to do this script, the VLBI data will still be recorded, but the 
CLASS header will have the standard object velocity, so the lines will 
appear to be at the wrong radial velocity.  If you go back to normal observing
and forget to turn off the FEORGA mode, the receiver will not be tuned 
to the line/velocity you want.


One more thing:  In VLBI mode, you ought to depress the VLBI button.  This 
disables the START button.  Instead, the Start will happen when the OBSINP
MEAS command is given (which is incorporated in the VLBI OBST scripts).
This is meant to get the telescope to start observing at a time controlled
by OBST.