The following from Phil's web page:

# model 0 oct97 -

* used 4 term model: offset, cosaz,sinaz,sinza.

* sband tx receiver with turret at 60.54 degrees.

* Sources from AO catalog (chris salter).

# model 1 dec97 -

* 10 terms. added sin(za)^2, sin(3az), cos(3az), sin(za-bal)*cos(3az) , sin(za-bal)*sin(3az), sin(za*57).

# model 7 jan98 -

* 13 terms. removed sin(za*57), added sin(2az), cos(2az), sin(6az), cos(6az).

So the pointing model results in the following corrections:

Let az and za be the desired ("ideal") coordinates and az' and za' be the commands, i.e. these commands will cause the encoders reach the same values, az' and za'.

The model is then

az' = az + az offset + A1 cos(az) + A2 sin( az) +A3 sina (za) + A4 sin(za)^2 +A5 sin(3az) + A6 cos(3az) +A7 sin(za-bal)*cos(3az) +A8 sin(za-bal)*sin(3az) + A9 sin(2az) +A10 cos(2az) +

+ A11 sin(6az) + A12 cos(6az)

za' = za + azoffset + B1 cosaz + B2 sin az +B3 sina za + B4 sin(za)^2 +B5 sin(3az) + B6 cos(3az)

+B7 sin(za-bal)*cos(3az) +B8 sin(za-bal)*sin(3az) + B9 sin(2az) +B10 cos(2az)

+ B11 sin(6az) +B12 cos(6az)

The parameter bal is the Gregorian zenith angle that balances the azimuth arm when the carriage house is at 10 degrees, its normal parking place. Including bal, there are a total of 27 parameters.

For the present pointing model (Model 15, May 2004), the parameters are:

bal =

azoffset =

zaoffset =

A1=

.....

.....

A12 =

B1 =

......

.....

B12=