Use case: do classical observing with a CCD

Purpose: general observing.

Actors: observer.

Outline: the observer alternates between these operations:

Setting the readout format (binning, windows, gain, speed).
Single, archived exposures.
Sequences of archived exposures.
Single exposures to test signal and location on the sky (glance, scratch).

For a given camera, the system does only one of these operations at a time.

Related use-cases:

Set readout format

Standard sequences:

Typical course of events:

User action System response

1. The use case begins when the user has started up the TCS, DAS, CIA and ICS successfully. The entries below can be combined in any order and with any number of repetitions.

2. User sets the parameters of a readout by running the user case set readout parameters System remembers the parameters for subsequent observations.

3. User asks for an single observation stating the exposure time and title. DAS closes the CCD shutter if it is open. DAS clears the CCD, exposes for the given time, and reads out the CCD. DAS executes the sequence read and store pixel data, producing a FITS image. DAS executes the sequence make FITS header, completing the FITS file. DAS executes the sequence save in archive file. The whole operation takes no more than 30s plus the exposure time.

4. User asks for a sequence of archived observations, stating number of exposures, the exposure time and title. The system repeats case 2 above for the given number of observations.

5. User selects a set of readout channels from a camera with more than one channel. System remember the set of channels. Subsequent readouts use only the requested channels.

	User action	System response
1.	The use case begins when the user has started up the TCS, DAS, CIA and ICS successfully. The entries below can be combined in any order and with any number of repetitions.
2.	User sets the parameters of a readout by running the user case set readout parameters	System remembers the parameters for subsequent observations.
3.	User asks for an single observation stating the exposure time and title.	DAS closes the CCD shutter if it is open. DAS clears the CCD, exposes for the given time, and reads out the CCD. DAS executes the sequence read and store pixel data, producing a FITS image. DAS executes the sequence make FITS header, completing the FITS file. DAS executes the sequence save in archive file. The whole operation takes no more than 30s plus the exposure time.
4.	User asks for a sequence of archived observations, stating number of exposures, the exposure time and title.	The system repeats case 2 above for the given number of observations.
5.	User selects a set of readout channels from a camera with more than one channel.	System remember the set of channels. Subsequent readouts use only the requested channels.

Variations:

Observation type may be bias, in which case there is no exposure.
Observation type may be dark, in which case the shutter doews not open and the delay between clear and readout is timed in the same way as for an exposure.
Observation may be a scratch run. System does save in scratch file instead of save in archive file.
Observation may be a glance run. System doesn't do save in archive file.