Sometimes it is necessary for engineering to move the building and let the
telescope follow. This way one gets a smoother movement of the building.

To enter this mode, you have to select computer control for azimuth on the
Krupp rack. Then go to the Koenigsbacher window and use one of the SMTSYS
windows to run the following commands:

SOMEPRIV
STOP FAHREN			! FAHREN should not have control over the
				! antenna
SET DEF KDATA:[SMT.PDP11]
RUN NULLA			! Clears AZ micro so that it does not send
				! the antenna elsewhere or stops it

SET DEF KDATA:[SMT.TEST]	! Special program to make the antenna follow
@FOLLOW_HOUSE			! the building

You will be asked for two optional amplification factors.  The defaults of 1.0
and 1.0 can be gotten by simply striking RETURN.  These work well enough and
generally keep the antenna centered to better than 0.1 degree except when
starting and stopping.  (Undoubtably these values could be improved if one took
the time.) 

Now go to Building Servo Unit in the control room.  It is the device which 
didn't fit into the half rack on the table and is sitting to the left of it
on the table.  The A/M button controls whether the building is in automatic (A)
mode following the telescope or in manual (M) mode, paying no attention to the
antenna position.  Toggle the A/M button to put the building into manual mode
(red LED lights up). Toggle the "D" button until you get a "V" display (the
character "V" lights in the upper right area). The display should show a number
around 50 which is the zero point (right now probably rather 49.8) where the
building is not moving. Use the knob to control the rate at which the building
moves CCW (50 to 100) or CW (50 to 0). The right bar graph shows the difference
angle between the building and the antenna. 0 and 100 are the limits. With the
default choice of amplification factors this graph will go up to 60 and down to
40.  Should it go beyond 85 or below 15, this will trip the hard limit in
azimuth and you have to do the "grey box trick" to get out of this situation. 

Once you are done with the work and want to get back into normal mode, move the
V value to 50, toggle the A/M button to automatic (A) (green LED lights up),
and strike CTRL-C in the FOLLOW_HOUSE window.  This will zero out the antenna
speed and take the antenna out of computer control.  DON'T WAIT VERY LONG
BEFORE STRIKING CTRL-C!  When FOLLOW_HOUSE is running and the building is in
Automatic mode, there is no "leader", both are trying to follow the other. This
is unstable equilibrium, and the antenna could start to slew. 

The following sequence will restart FAHREN:

    SET DEFAULT KDATA:[SMT.PDP11]
    @SMTLOADM
    FAHREN