telescope ephem pointing with sband

• The sband software would read the ephemeris.
  
• At a user specified rate, it would send ra,dec, offsets, and rates to the pointing program
• The rates would be computed by :
• sbtelpostm , users specifies the time for rates. The default is 900 seconds.
• sbtelpos looking different minutes in the ephemeris file.

Pointing problems:

• When the sband software was written (1990's)  the telescope pointing program did not support tracking an object using an ephemeris file. This functionality was put in the sband software.
  
• mono static object tracking:
  
• originally written for objects with slowly varying ra,dec.
• At the start of the transmit cycle:
• get tx apparent ra,dec at the start of the transmit cycle
• get rx apparent ra,dec at the start of the receive cycle
• compute a rate suing
  
• every minute:
• grab the apparent ra,dec from the ephemeris file for the requested time t0
  
• Compute a rate using the ra,dec  at t0 and a second value t1 (typically 1 minute in the future).
• Send the apparent ra,dec and computed rate to the pointing program.
• This worked well for planets, asteroids, etc...
• This mode of tracking does not
  
• take the apparent ra, dec from the ephemeris file and send  it to the pointing program.
• This was typically done on a 1 minute cycle.
  
• The code would also
  

    We had trouble with the sband control software.  

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