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".

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.

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 below resumes how much should be the maximum scanning velocity requested by the observer depending on the antenna elevation.

> elevation 	max. tracking
> (deg.) 	("/sec.)
> 20 	126
> 25 	121
> 30 	115
> 35 	108
> 40 	100
> 45 	91
> 50 	81
> 55 	71
> 60 	60
> 65 	48
> 70 	36
> 75 	24
> 76 	21
> 77 	19
> 78 	16
> 79 	14
> 80 	11
> 81 	8
> 82 	6
> 83 	3
> 84 	1
Anyway, it is recommended to keep some protective margin with respect to the previous values.