Use case: observe with Taurus

Purpose: to make etalon-spectroscopy observations

Actors: observer.

Outline: observer sets up the format for each readout and the number of etalon positions per observation. Observer carries out observations that produce data cubes, with one etalon position and readout per plane of the cube.

Realted use-cases:

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 adjusts the spectrograph through the ICS.

3. User defines the number of etalon positions in each observation. System remembers this number as the number of planes in a data cube needed to store each observation.

4. User sets the details of each readout (binning etc.) by running the use case set readout format System notes that these new details apply to all subsequent readouts.

5. User asks for a glance run, stating the exposure time and title. System sets up a file for a single, planar image. System closes the shutter, clears the CCDs, preflashes, exposes and reads out. In parallel, system executes the sequence make FITS header and read and store pixel data, completing the FITS file.

6. User asks for a bias frame. System sets up a file for a single, planar image. System closes the shutter, clears the CCDs, preflashes, exposes reads out. In parallel, system executes the sequence make FITS header and read and store data, completing the FITS file. DAS executes the sequence save to archive.

7. User asks for an observation stating the observation type (run, dark, sky, flat), exposure time and title. System sets up to receive a data cube of the previously given depth. System repeats this sequence for each plane of the cube:

ICS adjusts the etalon setting.
DAS closes the CCD shutter if it is open.
DAS clears the CCD, preflashes, exposes for the given time, and reads out the CCD
DAS executes the sequence read and store pixel data, producing a FITS image.
In parallel, DAS executes the sequence make FITS header, completing the FITS file. After all planes are done, DAS executes the sequence save to archive.

8. User repeats the steps above in any order.

	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 adjusts the spectrograph through the ICS.
3.	User defines the number of etalon positions in each observation.	System remembers this number as the number of planes in a data cube needed to store each observation.
4.	User sets the details of each readout (binning etc.) by running the use case set readout format	System notes that these new details apply to all subsequent readouts.
5.	User asks for a glance run, stating the exposure time and title.	System sets up a file for a single, planar image. System closes the shutter, clears the CCDs, preflashes, exposes and reads out. In parallel, system executes the sequence make FITS header and read and store pixel data, completing the FITS file.
6.	User asks for a bias frame.	System sets up a file for a single, planar image. System closes the shutter, clears the CCDs, preflashes, exposes reads out. In parallel, system executes the sequence make FITS header and read and store data, completing the FITS file. DAS executes the sequence save to archive.
7.	User asks for an observation stating the observation type (run, dark, sky, flat), exposure time and title.	System sets up to receive a data cube of the previously given depth. System repeats this sequence for each plane of the cube: ICS adjusts the etalon setting. DAS closes the CCD shutter if it is open. DAS clears the CCD, preflashes, exposes for the given time, and reads out the CCD DAS executes the sequence read and store pixel data, producing a FITS image. In parallel, DAS executes the sequence make FITS header, completing the FITS file. After all planes are done, DAS executes the sequence save to archive.
8.	User repeats the steps above in any order.

Variations:

Step 4 is missed out. Each readout, for biases, glances and planes of cubes, has the default format in the camera's profiles.
Step 3 is missed out. Each observation has the default number of planes specified in the camera's profiles.
In an observation other than a bias or glance, the user asks for storage in a scratch file. The system executes save in scratch file instead of save in archive file.