The user may optionally input the results of SYNPHOT calculations for the count rate per unit flux. There are two reasons for possibly doing this:
1) If one wants an accurate conversion from the intensity input to count rate (i.e. an accurate calibration of not only f and PA, but I as well), or:
2) If one wants an accurate calibration of the polarizer throughputs (~1% or better) which takes into account the spectral properties of the target.
However, if one merely wants an approxiamte calibration of only the fractional polarization (f) and PA, accurate to ~2%, then these parameters may be left set to zero, and the program will make some rough guesses about them.
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