Directions for Measuring the Azimuth Axis Tilt with the Inclinometer
	Bill Peters						29 Nov 00

    The tilt of the azimuth axis is best done by taking inclinimeter
measurements over 360 degrees of azimuth.  To check for elevation and/or
direction dependence, the measurements are be made while moving CW and CCW and
can be done with the antenna either near the horizon or near the zenith or
both.  The program, GET_INC, will take the measurements and write them to
files, a separate file for each direction and each elevation (if more than 
one elevation is selected).

    1) The selection of the observing procedure depends upon whether the
measurements are to be done at the horizon or the zenith.  If the sun is
between 0 and 40 degrees, do only the zenith measurement by typing
@TEL$OBS:INCL_CMAP Z. If the sun is above 50 degrees elevation, do only the
horizon measurement by typing @TEL$OBS:INCL_CMAP H.  (@TEL$OBS:INCL_CMAP with
no parameter will do both.  It is usually not necessary to do both.  In order 
to do both, one will have to skip turning off the ELEV drive button in Step 2.)

    This will setup an observing procedure to move the antenna 360 degrees
CW/CCW beginning in the north with the antenna at the horizon or the zenith, as
specified above.  The antenna will start in the CW or CCW wrap depending which
is closer.  (If the antenna is near 180 degrees, the wrong direction may be
selected, driving the antenna into the wrap limits at -90 or +450 degrees.  If
this should happen, stop the slew with the CANCEL button start over at Step 1.)
To prevent spurious aborts from Drumbeat et al, turn off the BACKEND,
FRONTEND, and DATA AC buttons. 

    2) Turn off the START button.  Get the antenna in position by pressing the
LOAD button or with OBST by typing 

	OBSINP LOAD 

When the telescope reaches the elevation requested, turn off the ELEV drive 
button.  (This allows the fork wobble to be measured in addition to the
tilt of the azimuth axis.)

    3) Run GET_INC from the SMTSYS account:  At an SMTSYS> prompt,

	RUN SYS$SMT:[SMT.TEST]GET_INC

    Type in the acquisition parameters as requested.  (Use the values 
recommended by GET_INC for a CMAP observation.)  Next GET_INC will type
"Waiting for antenna to move in Azimuth".  Press the START button. When the
antenna begins to move, GET_INC will say "Now measuring".  As each file is
opened, a message to this effect is printed.  The measurements written are also
typed.  If the antenna is stationary for about 30 seconds, GET_INC will close
its file and exit. 

    See file INCLINOMETER.FIT for directions on fitting the data.