attachment:Maximum_OTF_speed_vs_Elevation.txt of ListOfAstroTarget2012N5

   1 elevation 	max. tracking
   2 (deg.) 	("/sec.)
   3 20 	126
   4 25 	121
   5 30 	115
   6 35 	108
   7 40 	100
   8 45 	91
   9 50 	81
  10 55 	71
  11 60 	60
  12 65 	48
  13 70 	36
  14 75 	24
  15 76 	21
  16 77 	19
  17 78 	16
  18 79 	14
  19 80 	11
  20 81 	8
  21 82 	6
  22 83 	3
  23 84 	1
  24 
  25 Notes:
  26 
  27 At the moment the maximum antenna velocity for tracking a source is 150"/sec. Below that value the tracking error is good, we could say that the error is below 1". At tracking velocities higher than 150"/sec. must be avoided because the antenna switch to another controller less precise (used for large displacements in the sky) and then there is a steady pointing error about 10".
  28 
  29 The previous velocity 150"/sec. is in altazimuth coordinates. Just tracking a source at antenna low elevations implies antenna altazimuth velocities about 15"/sec. This altazimuth velocity increases at high elevations reaching values higher than 150"/sec. at higher antenna elevations than 83 deg.
  30 
  31 If in addition to the own movement of the source in the sky the observer request a scanning velocity, then the maximum antenna elevation must be corrected to avoid exceeding the 150"/sec. The table above resumes how much should be the maximum scanning velocity requested by the observer depending on the antenna elevation.