atcsucStopImageAlignmentIp

Use Case: Stop Image Alignment

Description: After VLTI ISS has finished Image Alignment, the ATCS updates its "VLTI Coude pointing reference point" and the AT subsystems are put back to a safe state.

Role(s)/Actor(s):
Primary: User (Operator, Maintenance, VLTI-ISS)
Secondary: Nasmyth Beacon

Priority: Major

Performance: A couple of seconds (10 to 15 seconds)

Frequency: After any Image Alignment (see Prepare for Image Alignment)

Package Assignment: Optical Adjustments.

Preconditions:

Nasmyth sub-system is switched On and ONLINE
FAS sub-system is ONLINE (if selected)
FSS sub-system is ONLINE (if selected)

Basic Course:

Send command STOPIALto stop Image Alignment.
ATCS updates the value stored in its database for "VLTI Coude pointing reference point" using the current X-Y position of the FSS X-Y Table (if FSS is selected) or the X-Y centroid position of the beacon image on the FAS (if the FAS is used).
ATCS Switches Off Nasmyth Beacon Light Source

Exception Course:

ATCS returns OK reply

Exception Course: Command failed

ATCS returns ERROR reply

Postconditions:

Beacons are switched Off
Optical Alignment Parameter file has been updated with VLTI Coude pointing reference point"
Entry in Log File has been created (parameters TBD)

Issues to be Determined or Resolved:
Note:
In addition to storing the "VLTI Coude pointing reference point" in the DB, it could be usefull to store the alpha/beta of M6 which is needed to place the Nasmyth Beacon on the "VLTI Coude pointing reference point" (this value shall be defined for a given Azimuth angle).

Last modified: Thu Jun 28 13:40:20 UTC 2001