The program requires the values of polarizer transmission for parallel and perpendicular waves. The program can either estimate these assuming a flat slectrum, or the user can input SYNPHOT results containing this information.
If no SYNPHOT results are given, it will assume a flat spectrum, derive an effective wavelength for the spectral filter, and use the polarizer transmissions at this wavelength. In nearly all cases this should be accurate to ~1 percent.
On the other hand, observations of targets with steep spectra in broad filters will probably benefit from a custom generated set of transmissions from SYNPHOT.
If one wishes to input these parameters, they may be calculated with the CALCPHOT task in SYNPHOT. One would run CALCPHOT three times, with the obsmode successively set to, e.g. for F555W:
wfpc2, f555w, a2d7 wfpc2, f555w, polq_par, a2d7 wfpc2, f555w, polq_perp, a2d7
The spectrum might, for example, be specified as rn(bb(5500),band(wfpc2,f555w),1.,fnu) which will creat a 5500K black-body spectrum and normalize it to 1 erg cm-2 s-1 Hz-1 in the observation band.
The output "form" would be specified as "counts."
The above thus has the results for the successive obsmode settings:
Obsmode Count rate per unit flux wfpc2,f555w,a2d15 1.459E28 wfpc2,f555w,a2d15,polq_par 9.648E27 wfpc2,f555w,a2d15,polq_perp 3.986E26
These values would then be input into the appropriate blanks on the fill-out form.
Note that SYNPHOT can model many different types of spectra. See SYNPHOT manual for further details.
J. Biretta, STScI