Use Case:  Set M2 Center Position

Description:  Set M2 center position. This case is used during telescope alignment procedure at begining of the night and/or whenever required by VLTICS-ISS/INS.

Role(s)/Actor(s): 
Primary: Operator, Maintenance
Secondary: M2

Priority: Critical

Performance: 1 second

Frequency:  Asynchronous, typically while alignement procedure, up to a couple of times per minute.

Package Assignment:  M2 Subsystem.

Preconditions: 

• M2 is ONLINE

Basic Course: 

• Send command SETCPOS <X,Y> to set M2 at given center position (X,Y)
  Exception Course: Command failed
• ATCS sends the command to M2 sub-system

  Interface:  IfM2.Centering.SetAbs,  IfM2.Centering.SetRel

  Exception Course: Command failed
• ATCS returns OK reply

Exception Course: Illegal center position

• (X,Y) position out of range (sqrt(X^2 + Y^2) < 0.7 mm)
  ATCS returns ERROR reply

Exception Course: Command failed

• ATCS returns ERROR reply

Postconditions: 

• M2 at center position

Issues to be Determined or Resolved: 

Notes:At INIT time, the mirror is moved at the configured center position, configurable in the OLDB (in mm and arcsec)

Last modified: Fri Nov 23 13:19:23 UTC 2001