Use Case:
Prepare for VLTI Focus Adjustment
Description:
Part of the focusing procedure (on general interferometer control level)
is to find the best focus for each telescope at the Combined Focus. In
this Use Case, the AT subsytems are setup to enable ISS to
perform the VLTI Focus Adjustment.
Role(s)/Actor(s):
Primary: User (Operator, Maintenance, VLTICS-ISS)
Secondary: Nasmyth Wheel
Priority:
Major.
Performance:
A
few seconds (10-15 seconds)
Frequency:
Whenever
necessary.
Preconditions:
-
A star for focusing has been selected
-
Telescope is Tracking (event. guiding or field stabilizing).
-
M2 in ONLINE
-
Nasmyth Wheel is ONLINE
Basic Course:
-
Send command PREPFOC to prepare for VLTI combined focus adjustment with Nasmyth Free-Hole or with Nasmyth Half-Masks
-
ATCS Sets
Nasmyth Wheel to requested position
-
ATCS sends final OK reply
Exception
Course: Command failed
-
ATCS sends final ERROR reply
Postconditions:
-
The subsytem are positioned as needed.
Issues to be Determined
or Resolved:
Notes:
As part of the AT Optical Alignment Parameters,
add the focus positions Coude-Focus-FAS, Coude-Focus-FSS
and Coude-Focus-VLTI
The most common configuration (i.e. highest priority) will be: Telescope
in Field Stabilisation, Free-hole configuration
When using the Nasmyth Half-Masks for focus adjustment the ISS will will use the chopping
features of the Nasmith Wheel by using in a loop:
Last modified: Thu Jun 28 13:40:15 UTC 2001
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