Use case: prepare to observe

Purpose: bring the DAS on-line.

Actors: observer or TO or DE; or any two of the above working together.

Subordinate use cases:

Outline: users start the sub-systems TCS and DAS, then start the CIA and ICS in the central sub-system. The system is then ready to use.

Typical course of events:

Action System response

1. The users come to the telescope and check the displays to see which sub-systems are running. The status displays make it obvious which parts of the observing system are running.

2. If the TCS is not running, one user works through use case start TCS. The system allows him/her to complete this within five minutes. Afterwards, the TCS is on-line.

3. If the DAS is not running, one user works through use case start DAS. The system allows him/her to complete this within five minutes. Aftwards, the DAS (server and controller programs) is on-line.

4. A user works through the use case start CIA and ICS. The system allows him/her to complete this within five minutes. Aftwards, the ICS servers are on-line, the status displays are on-line and the overall system is linked up and ready to use.

	Action	System response
1.	The users come to the telescope and check the displays to see which sub-systems are running.	The status displays make it obvious which parts of the observing system are running.
2.	If the TCS is not running, one user works through use case start TCS.	The system allows him/her to complete this within five minutes. Afterwards, the TCS is on-line.
3.	If the DAS is not running, one user works through use case start DAS.	The system allows him/her to complete this within five minutes. Aftwards, the DAS (server and controller programs) is on-line.
4.	A user works through the use case start CIA and ICS.	The system allows him/her to complete this within five minutes. Aftwards, the ICS servers are on-line, the status displays are on-line and the overall system is linked up and ready to use.