Minor tidying up in the second pass example config.

Author: welucas2

examples/imsim-user-instcat-ffp-pass2.yaml

@@ -10,12 +10,6 @@ template: imsim-config-instcat
 #  Make your changes below.
 ################################################################
 
-# Put your own commands that override the defaults below here.  For example
-# input.instance_catalog.file_name: ./imsim_cat_197356.txt
-# input.instance_catalog.sort_mag: False
-# input.tree_rings.only_dets: [R22_S11]
-# image.nobjects: 5
-
 input.checkpoint: ""
 # input.instance_catalog: ""
 input.instance_catalog.file_name: $os.environ.get('IMSIM_HOME')+'/imSim/examples/example_instance_catalog_ffp.txt'
@@ -25,6 +19,8 @@ input.instance_catalog.sort_mag: False
 input.tree_rings: ""
 input.atm_psf: ""
 
+# In the second pass, we add off-detector photons to the image generated in the
+# first pass from the the on-detector photons. Give the image here.
 input.initial_image:
     dir: output
     file_name:
@@ -37,17 +33,13 @@ input.initial_image:
             - $det_name
             - "@output.det_num"
 
-# Simple off detector photon input reading one file.
-# input.off_detector_photons:
-#     file_name: "output/off_det_00398414-0-r-R22_S11-det094.fits"
-#     camera: $camera
-#     det_name: $det_name
-
-# If we're doing the preprocessing step then we've already reorganised the
-# photons so they live in one file per destination detector, so we only need to
-# read that one. But, we might feasibly also wish to directly specify a list of
-# off-detector photon files, which presumably haven't been preprocessed, so I
-# might want to add the capability to work from a file list too.
+# Two methods can be used to read files containing off-detector photons. If a
+# single file only is to be read, then give the file_name. Alternatively, we can
+# give a file_pattern containing the fields DETNAME and DETNUM, which are
+# wildcards for the detector name and number in an expected set of files
+# matching the pattern. The loader will then attempt to read from all files it
+# finds matching this patter, excluding the file with the same name/num as the
+# current detector.
 input.off_detector_photons:
     dir: output
     # file_name: