fill out ephemeris used to determine velocity

romanisim/image.py

@@ -879,10 +879,6 @@ def make_asdf(slope, slopevar_rn, slopevar_poisson, metadata=None,
     # ref_file: conceptually sound when we work from crds reference
     #     files
     # target: can push forward from APT file
-    # velocity_aberration:  I guess to first order,
-    #     ignore the detailed orbit around L2 and just project
-    #     the earth out to L2, and use that for the velocity
-    #     aberration?  Don't do until someone asks.
     # visit: start_time, end_time, total_exposures, ...?
     # wcsinfo: v2_ref, v3_ref, vparity, v3yangle, ra_ref, dec_ref
     #     roll_ref, s_region

romanisim/parameters.py

@@ -35,6 +35,14 @@
                    'detector': 'WFI07',
                    'optical_element': 'F184',
                    },
+    'ephemeris': {'time': Time('2026-01-01').mjd,
+                  'spatial_x': 0.,
+                  'spatial_y': 0.,
+                  'spatial_z': 0.,
+                  'velocity_x': 0.,
+                  'velocity_y': 0.,
+                  'velocity_z': 0.
+                  },
     'exposure': {'start_time': Time('2026-01-01T00:00:00'),
                  'type': 'WFI_IMAGE',
                  'ma_table_number': 1,
@@ -44,6 +52,7 @@
                  'target_dec': 66.0,
                  'target_aperture': 'WFI_CEN',
                  },
+    'velocity_aberration': {'scale_factor': 1.0},
     'wcsinfo': {'aperture_name': 'WFI_CEN',
                 'pa_aperture': 0.,
                 'ra_ref': 270.0,
@@ -56,7 +65,6 @@
                 # I don't know what vparity and v3yangle should really be,
                 # but they are always -1 and -60 in existing files.
                 },
-    'velocity_aberration': {'scale_factor': 1.0},
 }
 
 # Default metadata for level 3 mosaics

romanisim/ris_make_utils.py

@@ -10,6 +10,7 @@
 from astropy import table
 from astropy import time
 from astropy import coordinates
+from astropy import units as u
 import galsim
 from galsim import roman
 import roman_datamodels
@@ -98,6 +99,18 @@ def set_metadata(meta=None, date=None, bandpass='F087', sca=7,
         scale_factor = calc_scale_factor(meta['exposure']['start_time'], meta['wcsinfo']['ra_ref'], meta['wcsinfo']['dec_ref'])
     meta['velocity_aberration']['scale_factor'] = scale_factor
 
+    # Fill out some ephemeris information, presuming all is earth.
+    position, velocity = coordinates.get_body_barycentric_posvel('earth', meta['exposure']['start_time'])
+    position = position.xyz.to(u.km)
+    velocity = velocity.xyz.to(u.km / u.s)
+    meta['ephemeris']['time'] = meta['exposure']['start_time'].mjd
+    meta['ephemeris']['spatial_x'] = position.value[0]
+    meta['ephemeris']['spatial_y'] = position.value[1]
+    meta['ephemeris']['spatial_z'] = position.value[2]
+    meta['ephemeris']['velocity_x'] = velocity.value[0]
+    meta['ephemeris']['velocity_y'] = velocity.value[1]
+    meta['ephemeris']['velocity_z'] = velocity.value[2]
+
     return meta