Initial implementation of Roman PSF

devel/roman/.gitignore

@@ -0,0 +1,5 @@
+ffov_13906_test_v251020.fits
+stars_13906_test_v251105.parquet
+Roman_SRR_WFC_Pupil_Mask_Shortwave_2048_reformatted.fits.gz
+*.png
+*.piff

devel/roman/piff.yaml

@@ -0,0 +1,76 @@
+input:
+
+    # This file is quite large, so not saved in the repo.
+    # It and the cat_file are available from here:
+    #   https://drive.google.com/drive/folders/1akvHjdKSTMppPTcNfXjEy9SVq_hFBDBc
+    image_file_name: 'ffov_13906_test_v251020.fits'
+    image_hdu: [1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18]  # hdu = SCA
+    badpix_zeros: True
+
+    cat_file_name: 'stars_13906_test_v251105.parquet'
+
+    ra_col: ra
+    dec_col: dec
+    properties:
+        sca: '$@image_num + 1'
+    noise: BKGNDVAR
+    gain: EQVGAIN
+    sky: median
+
+    stamp_size: 25
+
+select:
+
+    min_snr: 50           # reject very faint stars
+    max_snr_weight: 500   # don't over-weight very bright stars
+    #max_mask_pixels: 10   # how many pixels in stamp are allowed to be masked.
+    hsm_size_reject: 5    # number of inter-quartile ranges from median to reject size estimate.
+    max_pixel_cut: 50000  # reject stars with a pixel value higher than this. (sort of)
+    min_sep: 1.0          # reject stars with a neighbor closer than 1 arcsec away.
+    #nstars: 100
+
+output:
+    file_name: 'ffov_13906_1.piff'
+
+    stats:
+        - 
+          type: StarImages
+          file_name: stars.png
+          nplot: 0  # all stars
+
+psf:
+
+    type: Sum
+
+    components:
+
+      -
+        type: RomanOptics
+        filter: H158
+        chromatic: False
+        max_zernike: 12    # Fit Zernike coefficients 4-12 inclusive.
+        aberration_prior_sigma: 0.05   # Gaussian prior on all Zernike coefficients in absolute units.
+        nproc: 4
+
+      - 
+        type: Simple
+        model:
+            type: PixelGrid
+            scale: 0.11
+            size: 5
+        interp:
+            type: BasisPolynomial
+            order: 2
+
+    outliers:
+      -
+        type: Chisq
+        nsigma: 5
+        max_remove: 0.01
+      -
+        type: Centroid
+        max_offset: 0.2 # arcsec
+
+
+
+verbose: 2

piff/__init__.py

@@ -118,6 +118,7 @@
 # Leave these in their own namespaces
 from . import util
 from . import des
+from . import roman
 from . import wavefront
 from . import meta_data
 from . import readers

piff/roman/__init__.py

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+# Copyright (c) 2026 by Mike Jarvis and the other collaborators on GitHub at
+# https://github.com/rmjarvis/Piff  All rights reserved.
+#
+# Piff is free software: Redistribution and use in source and binary forms
+# with or without modification, are permitted provided that the following
+# conditions are met:
+#
+# 1. Redistributions of source code must retain the above copyright notice, this
+#    list of conditions and the disclaimer given in the accompanying LICENSE
+#    file.
+# 2. Redistributions in binary form must reproduce the above copyright notice,
+#    this list of conditions and the disclaimer given in the documentation
+#    and/or other materials provided with the distribution.
+
+"""
+Some specialized features that specific to the DES survey and the DECam camera.
+"""
+
+from .roman_psf import RomanOpticsPSF, RomanOpticalModel, RomanSCAInterp