CCDS-Specific Prospero Commands

In addition to the general Prospero commands for taking data, there are a number of special commands specific to the CCDS:

Grating Setup

These commands must be used whenever the grating is changed, or after restarting Prospero for any reason.

GROOVES - set the grating ruling in grooves/mm

Example: GROOVES 350 for the 350 grooves/mm grating

ORDER - set the order of the grating

Example: ORDER 1 for first order

GRSETUP - Prompt user for grooves and order info. A novice version of GROOVES and ORDER

Grating Tilt

These commands are used to control the tilt of the grating to select a specific central wavelength.

CENTER - set the central wavelength

Example: CENTER 5520 - set the central wavelength to 5520Å

NEWCENTER - recalibrate the central wavelength

Example: NEWCENTER 5500 - tell CCDS that the actual central wavelength is 5500Å, correcting any zero-point offset.

This is done if you select a central wavelength using CENTER and find that the actual central wavelength is different.

GRATZERO - tilt the grating to the zero-th order position

GRATTILT - tilt the grating to a specific device-encoder setting.

Example: GRATTILT 59100 - commands the grating to tilt to the position defined by 59100 encoder units. This is a low-level command that should only be used if you want to scan the grating without reference to wavelength (like CENTER).

Grating System Reset and Status

These are engineering commands used to reset the grating mechanism (e.g., before or after a grating change or major IE fault), or to check the current values of the grating system parameters when debugging problems.

GRESET - reset the grating tilt mechanism

Used to reset the tilt mechanism by driving the grating to its home position (well past zero-th order). This operation takes 3-4 minutes and should only be done if absolutely necessary.

GRATPARS - print the current CCDS Grating Parameters

This command dumps the internal Grating parameter tables to the screen. These data are only useful for engineering or troubleshooting problems.