Implemented new definition of (u,v) points

stix/idl/processing/imaging/stx_em.pro

@@ -38,6 +38,7 @@
 ;          June 2022, Massa P., 'aux_data' added
 ;          August 2022, Massa P., made it compatible with the up-to-date imaging software and added backrgound correction
 ;                       in the EM iterative scheme
+;          July 2023, Massa P., made it compatible with the new definition of (u,v)-points (see stx_uv_points)
 ;             
 ;CONTACT: massa.p@dima.unige.it
 
@@ -104,15 +105,11 @@ end
 phase_corr = grid_phase_corr + ad_hoc_phase_corr + phase_factor
 phase_corr *= !dtor
 
-;;**************** Giordano's (u,v) points
+;;**************** Define (u,v) points
 
-subc_str = stx_construct_subcollimator()
-
-uv = stx_uv_points_giordano()
-u = -uv.u * subc_str.phase
-v = -uv.v * subc_str.phase
-u = u[subc_index]
-v = v[subc_index]
+uv_data = stx_uv_points(subc_index)
+u = uv_data.u
+v = uv_data.v
 
 ;;**************** Transmission matrix
 

stix/idl/processing/imaging/stx_estimate_flare_location.pro

@@ -38,6 +38,7 @@
 ;           (default, 0)
 ;   
 ; HISTORY: October 2022, Massa P. (WKU), initial release
+;          July 2023, Massa P., made it compatible with the new definition of (u,v)-points (see stx_uv_points)
 ;
 ; CONTACT:
 ;   paolo.massa@wku.edu
@@ -62,20 +63,10 @@ pixel = rsun * 2.6 / imsize ; 2.6 is chosen arbitrarily so that field of view Ba
 ;;******* Construct the visibility structure
 mapcenter_stix = stx_hpc2stx_coord(mapcenter, aux_data)
 
-vis = stx_construct_visibility(path_sci_file, time_range, energy_range, mapcenter_stix, $
+vis = stx_construct_calibrated_visibility(path_sci_file, time_range, energy_range, mapcenter_stix, $
                                           path_bkg_file=path_bkg_file,subc_index=subc_index,  /silent, $
                                           _extra=extra)
 
-;;******* Use Giordano's (u,v) points: no need to perform projection correction (see Giordano et al., 2015)
-subc_str = stx_construct_subcollimator()
-uv = stx_uv_points_giordano()
-u = -uv.u * subc_str.phase
-v = -uv.v * subc_str.phase
-vis.u = u[subc_index]
-vis.v = v[subc_index]
-
-vis = stx_calibrate_visibility(vis)
-
 ;;******* Compute the Back Projection map
 bp_nat_map = stx_bproj(vis,imsize,pixel,aux_data)
 

stix/idl/processing/imaging/stx_uv_points.pro

@@ -0,0 +1,47 @@
+;+
+;
+; NAME:
+;   stx_uv_points
+;
+; PURPOSE:
+;   Compute the coordinates of the (u,v) points sampled by specific STIX sub-collimators. For more information, we refer to:
+;   
+;   - Giordano et al., "The Process of Data Formation for the Spectrometer/Telescope for Imaging X-rays 
+;     (STIX) in Solar Orbiter", SIAM Journal on Imaging Sciences, 2015
+;     
+;   - Massa et al., "STIX imaging I - Concept", arxiv, 2023
+;
+; CALLING SEQUENCE:
+;   uv_points = stx_uv_points(subc_index)
+;
+; INPUTS:
+;   subc_index: array containing the indices of the subcollimators to be considered for computing the (u,v) points
+;
+; KEYWORDS:
+;   d_sep: distance between the front and the rear grid [in mm]. Default, 545.30
+;   
+;   d_det: distance between the rear grid and the detector [in mm]. Default, 47.78
+;
+; HISTORY: July 2023, Massa P. (WKU), based on 'stx_uv_points_giordano'
+;
+; CONTACT:
+;   paolo.massa@wku.edu
+;-
+
+function stx_uv_points, subc_index, d_sep=d_sep, d_det=d_det
+
+default, d_sep, 545.30
+default, d_det, 47.78
+
+subc_str = stx_construct_subcollimator()
+subc_str = subc_str(subc_index)
+
+factor_f = (d_sep + d_det) / subc_str.front.pitch / 3600.0d / !RADEG ;; in arcsec^-1
+factor_r = d_det / subc_str.rear.pitch / 3600.0d / !RADEG            ;; in arcsec^-1
+
+u = -subc_str.PHASE * (cos(subc_str.front.angle * !dtor) * factor_f - cos(subc_str.rear.angle * !dtor) * factor_r)
+v = -subc_str.PHASE * (sin(subc_str.front.angle * !dtor) * factor_f - sin(subc_str.rear.angle * !dtor) * factor_r)
+
+return, {u:u, v:v}
+
+end

stix/idl/processing/vis/stx_calibrate_visibility.pro

@@ -19,11 +19,9 @@
 ;
 ; KEYWORDS:
 ; 
-;   phase_calib_factors: 32-element array containing the phase calibration factors for each detectors (degrees).
+;   phase_calib_factors: 32-element array containing the phase calibration factors for each detector (degrees).
 ;                        The default phase calibration factors consist of four terms:
 ;                         - a grid correction factor, which keeps into account the phase of the front and the rear grid;
-;                         - a projection correction factor, if the 'xy_flare' estimate of the flare location is provided 
-;                           in the visibility structure;
 ;                         - an "ad hoc" phase correction factor, which removes systematic residual errors. 
 ;                           The cause of these systematic errors is still under investigation;
 ;                         - a factor which is added so that the reconstructed image is centered in the 
@@ -46,6 +44,8 @@
 ;   Calibrated 'stx_visibility' structure.
 ;
 ; HISTORY: August 2022, Massa P., created
+;          July 2023, Massa P., removed visibility phase 'projection correction' since the new definition of 
+;          (u,v)-points is adopted (see stx_uv_points).
 ;
 ; CONTACT:
 ;   paolo.massa@wku.edu
@@ -63,26 +63,17 @@ modulation_efficiency = !pi^3./(8.*sqrt(2.))
 
 ;; Grid phase correction
 tmp = read_csv(loc_file( 'GridCorrection.csv', path = getenv('STX_VIS_PHASE') ), header=header, table_header=tableheader, n_table_header=2 )
-grid_phase_corr = tmp.field2[vis.ISC - 1]; * (-vis.phase_sense)
-
-;; Projection correction factor
-xy_flare = vis[0].XY_FLARE
-phase_proj_corr  = fltarr(n_vis)
-if ~xy_flare[0].isnan() then begin
-  proj_corr_factor = -xy_flare[0] * 360. * !pi / (180. * 3600. * 8.8) * (r2d_sep + f2r_sep/2.)
-  phase_proj_corr = phase_proj_corr + proj_corr_factor
-  ;phase_proj_corr  = phase_proj_corr * (-vis.phase_sense)
-endif
+grid_phase_corr = tmp.field2[vis.ISC - 1]
 
 ;; "Ad hoc" phase correction (for removing residual errors)
 tmp = read_csv(loc_file( 'PhaseCorrFactors.csv', path = getenv('STX_VIS_PHASE')), header=header, table_header=tableheader, n_table_header=3 )
-ad_hoc_phase_corr = tmp.field2[vis.ISC - 1]; * (-vis.phase_sense)
+ad_hoc_phase_corr = tmp.field2[vis.ISC - 1]
 
 ;; Mapcenter correction
 phase_mapcenter_corr = -2 * !pi * (vis.XYOFFSET[0] * vis.U + vis.XYOFFSET[1] * vis.V ) * !radeg
 
 default, amp_calib_factors, fltarr(n_vis) + modulation_efficiency
-default, phase_calib_factors, grid_phase_corr + ad_hoc_phase_corr + phase_proj_corr + phase_mapcenter_corr
+default, phase_calib_factors, grid_phase_corr + ad_hoc_phase_corr + phase_mapcenter_corr
 default, syserr_sigamp, 0.05 ;; 5% systematic error in the visibility amplitudes; arbitrary choice
 
 if vis[0].CALIBRATED eq 1 then message, "This visibility structure is already calibrated"

stix/idl/processing/vis/stx_pixel_data_summed2visibility.pro

@@ -52,6 +52,7 @@
 ;   - CALIBRATED: 0 if the values of the visibility amplitudes and phases are not calibrated, 1 otherwise   
 ;   
 ; HISTORY: August 2022, Massa P., created
+;          July 2023, Massa P., made it compatible with the new definition of (u,v)-points (see stx_uv_points)
 ;
 ; CONTACT:
 ;   paolo.massa@wku.edu
@@ -77,16 +78,9 @@ subc_str = subc_str[subc_index]
 
 ;;************** Define (u,v) points
 
-; take average of front and rear grid pitches (mm)
-pitch = (subc_str.front.pitch + subc_str.rear.pitch) / 2.0d
-; take average of front and rear grid orientation
-orientation = (subc_str.front.angle + subc_str.rear.angle) / 2.0d
-; convert pitch from mm to arcsec
-pitch = pitch / f2r_sep * 3600.0d * !RADEG
-; calculate u and v
-uv = 1.0 / pitch
-u = uv * cos(orientation * !DTOR) * (-subc_str.PHASE) ; TO BE REMOVED!
-v = uv * sin(orientation * !DTOR) * (-subc_str.PHASE) ; TO BE REMOVED!
+uv_data = stx_uv_points(subc_index)
+u = uv_data.u
+v = uv_data.v
 
 ;;************** Define visibility values