Southern African Large Telescope

Prime Focus Imaging Spectrograph

PFIS PI Planning Tool Design Description


Brian L Babler

Modification Record
Version Date Comments
1.0 18-Jul-2003 Preliminary Version

The PFIS PI Planning Tool will be a java application tool. The prospective PFIS user will input his/her desired target(s) (or provide an appropriately formatted file for input) as well as the target's magnitude (or surface brightness), and a choice of spectral energy distribution. Also required will be a selection of sky brightness (dark, grey, or bright) and degree of seeing (good, median, or poor). Finally the desired amount of exposure time or level of signal-to-noise will be chosen.

Following these inputs the user will select which mode of observing is desired, Imaging, Spectroscopy, or Fabry-Perot, and if Polarimetry is to be performed. Upon selection of the specfic observing mode, the permitted configuration options for that mode will then be highlighted and selectable. Illegal instrument configurations will not be allowed. Configurations which are technically not illegal but would result in impractical data will generate a 'red-flag'. This type of configuration will produce a commentary box requesting the user to submit an explanation of the proposed setup configuration and explain that the chosen setup may be an unsupported mode of operation. There will be several configuration options which will produce automatic selection of other configuration options, in these cases if the user chooses to override the automatic selection option, again a red-flag will be issued requesting explanation.

For example, with long-slit spectroscopy, the selection of a grating and central wavelength will automatically select the appropriate grating angle, if the user chooses to select a different grating angle then the user would be requested to explain why the grating angle selection was overridden. Configurations that produce a red flag are considered non-standard set-ups.

With the configuration options set, a COMPUTE button will enable an automatic calculation of the desired S/N output. The output will be a plot of S/N versus wavelength (for spectroscopy) or versus magnitude (for imaging). For cases where the S/N was inputted and an exposure time is the desired output, the exposure time will be calculated and displayed for the central wavelength of the chosen configuration and the resultant S/N plot will be displayed.

See general flowchart of PI Planning Tool.

See configuration options for Imaging observing mode.

See configuration options for Spectroscopy observing mode.

See configuration options for Fabry-Perot observing mode.