I’m trying to make a tool that allows the user to compute anything they ever wanted to know about spectrographs. It’s here:
DESIGN YOUR OWN SPECTROGRAPH: http://nickkonidaris.github.io/SpectrographCalculator/
The default parameters are for DBSP on the Hale 200-inch telescope. The parameters are listed the following format:
Parameter name (variable name) [ text box with value ]
If you put your mouse over a parameter name, you’ll see how the value is computed. The page displays the actual code to compute the variable. I know, documentation is needed.
1) The final variable called “pixel system throughput” (PST) allows you to compute the watt per pixel expected. Given a spectral irradiance from the source in erg / s / cm2 / Ang multiply by PST and you’re good to go.
2) If you’re worried about echelle spectrographs, set the grating rotation (grotate) to 0.