Option 1: direct conversion from iraf to python

Description

Option 1 would consist on implementing this into python. Most of this has been done already. But we probably need to review the code and compare it with this flowchart.

flow chart

This is a flow chart for dsimulator.

Some notes about it.

The input/output in light blue is in the sky plane. The input/output in green is the mask plane.
Iraf procedures are in CAPITAL letters.
The only use of actual distorsions is in LEN_SLITS. This procedure, which is triggered if ADJ_SLIT = YES, only affects the slit edges.

# Open X-Projection mapping
        fdx = open (XPROJ_MAP, READ_ONLY, TEXT_FILE)
        call gs_ingest (fdx, asfx, asfy)

      ......
# We will need to recalculate something ...

                xlow = X2(sdat,ndx1) + SLIT_GAP(indat)
                xupp = X1(sdat,ndx2) - SLIT_GAP(indat)
                xcen = 0.5 * (xlow + xupp)

                yas = Y2(sdat,ndx1)
                dxlow = gseval (asfx, xcen, yas)
                yas = Y1(sdat,ndx2)
                dxupp = gseval (asfx, xcen, yas)
                dxavg = 0.5 * (dxupp + dxlow)
                dxlow = dxlow - dxavg
                dxupp = dxupp - dxavg
call eprintf ("%6.3f %6.3f\n")
call pargr (dxlow)
call pargr (dxupp)

                if (pc1 == CODE_AS) {
                        del1 = 0.
                        del2 = X1(sdat,ndx2) - xlow - (dxupp - dxlow)
                } else if (pc2 == CODE_AS) {
                        del1 =  xupp - X2(sdat,ndx1) + (dxlow - dxupp)
                        del2 = 0.
                } else {
                        del1 = xcen - 0.5*SLIT_GAP(indat) - X2(sdat,ndx1) + dxlow
                        del2 = X1(sdat,ndx2) - (xcen + 0.5*SLIT_GAP(indat)) - dxupp
                }



                X2(sdat,ndx1) = X2(sdat,ndx1) + del1
                if (del1 != 0. && RELPA(sdat,ndx1) != INDEF) {
                        tana = tan (RELPA(sdat,ndx1))
                        Y2(sdat,ndx1) = Y2(sdat,ndx1) + del1 * FLIP * tana
                }

                X1(sdat,ndx2) = X1(sdat,ndx2) - del2
                if (del2 != 0. && RELPA(sdat,ndx2) != INDEF) {
                        tana = tan (RELPA(sdat,ndx2))
                        Y1(sdat,ndx2) = Y1(sdat,ndx2) - del2 * FLIP * tana
                }

The other distorsion (based on an optical model of Keck) is done at GNOM_TO_DPROJ procedure.

#
# GNOM_TO_DPROJ: adjust gnomonic coords to curved surface, take projection
# onto plane, and apply distortion correction, resulting in distortion-
# adjusted projected coords ready for a vertical projection to slitmask.
# Double inputs, outputs;  outputs may be the same arguments as inputs.
#
#####
## NB: We assume Sutin's ray trace is already producing radii to curved surface.
####

procedure gnom_to_dproj (xg, yg, xd, yd)

double  xg, yg                  # x,y gnomonic projection
double  xd, yd                  # returned x,y projected on plane (distorted)

double  rho                     # radius of input angle (approx from h)
double  cosa, sina              # cos, sin of azimuth in image plane

begin
        rho= sqrt (xg * xg + yg * yg)
        cosa = yg / rho
        sina = xg / rho

# Apply map gnomonic projection --> real telescope
        rho = rho * (1. + DIST_C0 + DIST_C2 * rho * rho)
        xd = rho * sina
        yd = rho * cosa
end

In this procedure, DIST_C0 = 0.0e-4 and DIST_C2 = -1.111311e-8

Staff Astronomers

Option 1: direct conversion from iraf to python

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Description

flow chart

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