Use Case:  Offset Alt/Az

Description:  Offset the Altitude and/or Azimuth axes of the given (alt,az) step.
The offset step is relative to the current position of the telescope (i.e. consecutive offset steps are accumulated). This command can be used only with the telescope standing still in a fixed position.

Role(s)/Actor(s): 
Primary: Operator, Maintenance
Secondary: Alt/Az Axis

Priority: Critical

Performance: up to 1.5 deg/sec in Alt and 2 deg/sec in Az

Frequency: Asynchronous up to 10 Hz

Package Assignment:  Tracking.

Preconditions: 

• ATCS is ONLINE
• Telescope standing still

Basic Course: 

• Send commandOFFSAA to offset the telescope of (Alt,Az) in arcsec
  Exception Course: Command failed
• ATCS sends the new offsets to Alt/Az axis

  Interface:  IfAltDrive,  IfAzDrive

  Exception Course: Command failed
• ATCS returns OK reply

Exception Course: Command failed

• ATCS returns ERROR reply

Postconditions: 

• Alt/Az axis are offset of the (alt,az) amount

Issues to be Determined or Resolved: 

Notes:

Last modified: Thu Jun 28 13:58:24 UTC 2001