Data Acquisition

The following is an example sequence for data acquisition:

• CCD wipe

• Exposure (open and close of the shutter. Shutter is not opened for dark data. Exposure is not done for bias data).

• Acquisition of the status of the environment and instrument at start, middle and end of the exposure.*

• Readout of CCD data.

• Acquisition of frame ID (see Section ).

• Production of FITS format data.

• Data transfer to OBC.

• Display data on OBS.

* The status of parameters that are variable during the exposure (e.g., the pointing of telescope, angle of the image rotator) is obtained at the start, middle and end of each exposure. These are written in the FITS header.

Data acquisition for objects and calibration sources are done with the following abstract commands.

Table 10: Commands for data acquisition

command	function	parameter
GetObject	data acquisition for object	ExpTime (exposure time) [sec]
GetStandard	data acquisition for standard star	ExpTime (exposure time) [sec]
GetComparison	data acquisition for Th-Ar	ExpTime (exposure time) [sec]
GetOBEFlat	data acquisition for flat (halogen lamp)	ExpTime (exposure time) [sec]
GetDark	acquisition of dark data	ExpTime (time) [sec]
GetBias	acquisition of bias data	-

The data set obtained by one exposure consist of two FITS files, corresponding to the two CCDs. The characteristics of the data are explained in Section .