REPEATABILITY TESTS FOR THE AZIMUTH AXIS


These numbers represent the deviation along the drive circle measured with a 
dial indicator after the telescope is driven away from a position by a given 
distance (in encoder counts) at a given rate (in encoder counts/sec) and then 
driven back.  The scale is roughly 5 arcsec per 0.001 inches.  Errors are of the 
order of 0.0005 inches (+/-3 arcsec).  We used the number of steps under "Distance"; 
the corresponding angles are very approximate.  The oscillation test drives the axis 
sinusoidally and looks for the amplitude of the changes in position.


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Rate -->            10 cps          200 cps         2500 cps         70,000 cps
________________________________________________________________________________
              |
Distance      |
              |
6,000 steps   |    0.0000in         0.0005in        0.0000in           N/A
(10 arcmin)   |                     0.0000          0.0000             
              |                    -0.0009          0.0000             
              |                     0.0000                       
              |                     0.0000                       
              |
36,000 steps  |      N/A           -0.0006         -0.0004             N/A
(1 deg)       |                    -0.0006          0.0000             
              |
360,000 steps |      N/A              N/A           0.0004           0.0000
(10 deg)      |                                     0.0018           0.0002  
              |                                                      0.0005  
              |
725,000 steps |      N/A              N/A           0.0001          -0.0012
(20 deg)      |                                     0.0009          -0.0003  
              |                                    -0.0002          -0.0025  
              |                                                     -0.0025  
              |
2,225,000 stps|      N/A              N/A             N/A            0.0080
(60 deg)      |                                                     -0.0013  
              |                                                      0.0059  
              |                                                      0.0050  
              |                                                      0.0020  
              |                                                      0.0020  
              |                                                      0.0030  
              |
8,000,000 stps|      N/A              N/A             N/A           -0.014
(full range)  |                                                     -0.008  
              |                                                     -0.014  
              |                                                     -0.014  
              |                                                     -0.014  
              |                                                      0.017  
              |                                                      0.019  
              |                                                      0.016  
______________|________________________________________________________________
              |
              |
Oscillation   |   Range = 0.0015 in 
test          |
______________|________________________________________________________________






These numbers represent the deviation along the drive circle (appx 50 inches 
in radius) measured with a dial indicator after the telescope is driven away from 
a position by a given distance (in encoder counts) at a given rate (in encoder 
counts/sec) and then driven back.