Use Case:  Calibrate Az axis

Role(s)/Actor(s):
Primary: User (Operator, Maintenance, VLTI-ISS)
Secondary:   Azimuth axis, Nasmyth Beacon, M6, Coude Beam Switching Device, FAS, FSS Filter Wheel

Priority: Major

Performance: A couple of minutes (3-10 minutes)

Frequency: Asynchronous, typ. once after relocation, or any time for maintenance/test purpose

Package Assignment:  Optical Adjustments.

Preconditions:

• FAS sub-system is ONLINE (if selected)
• FSS sub-system is ONLINE (if selected)
• CBSD at the right position (FSS or FAS)
• Nasmyth wheel in Beacon position
• Telescope Azimuth axis ONLINE

• Send command CALAZ to calibrate Az axis
• ATCS sets CBSD to appropriate postion (FSS or FAS)
• ATCS sets NDF to appropriate value
• ATCS sets Nasmyth Beacon Intensity level to appropriate value for Az axis calibration
• ATCS switches ON Nasmyth Beacon
• ATCS centers M6
• ATCS moves Azimuth axis on 360° by step and for each step record X-Y positions of beacon image on FAS (or FSS)

Alternate Course: ATCS moves Azimuth continously and record long exposure with FAS (more complicated for image processing => may be dropped)
• ATCS computes best-fit center of obtained circle
• ATCS updates the "Azimuth axis reference point"
• ATCS switches OFF Nasmyth Beacon
• ATCS sends final OK reply

• ATCS returns ERROR reply

• Azimuth axis reference is updated
• Nasmyth Beacon OFF
• Entry in Log File has been created (parameters TBD)

Notes:

Last modified: Thu Feb 28 10:37:49 UTC 2002