satellite streaks from instance catalogs

imsim/instcat.py

@@ -211,6 +211,7 @@ def _load(self, logger=None):
             'point' : 13,
             'sersic2d' : 17,
             'knots' : 17,
+            'streak' : 16
         }
         default_dust_index = 15  # For fits files
 
@@ -264,7 +265,10 @@ def _load(self, logger=None):
                     sed = ((tokens[5], float(tokens[6])))
                     # gamma1,gamma2,kappa
                     lens = (float(tokens[7]), g2_sign*float(tokens[8]), float(tokens[9]))
-                    # what are 10,11?
+                    # Columns 10 and 11 are delta_ra, delta_dec, which
+                    # are additional offsets in RA, Dec, optionally
+                    # used by phosim.  imSim does not use these
+                    # columns.
                     dust_index = dust_index_dict.get(tokens[12].lower(), default_dust_index)
                     objinfo = tokens[12:dust_index]
                     dust = tokens[dust_index:]
@@ -480,6 +484,17 @@ def getObj(self, index, gsparams=None, rng=None, exptime=30, logger=None):
         if params[0].lower() == 'point':
             obj = galsim.DeltaFunction(gsparams=gsparams)
 
+        elif params[0].lower() == 'streak':
+            # Note that satellite streaks are not sources at infinity
+            # and so would be out-of-focus compared to stars or
+            # galaxies and would therefore have a different PSF.  This
+            # implementation does not account for that difference.
+            length = float(params[1])
+            width = float(params[2])
+            obj = galsim.Box(length, width, gsparams=gsparams)
+            position_angle = galsim.Angle(float(params[3]), galsim.degrees)
+            obj = obj.rotate(position_angle)
+
         elif params[0].lower() == 'sersic2d':
             a = float(params[1])
             b = float(params[2])

tests/data/satellite_streak.txt

@@ -0,0 +1,22 @@
+rightascension 53.00913847303155535
+declination -27.43894880881512321
+mjd 59580.13974597222113516
+altitude 66.34657337061349835
+azimuth 270.27655488919378968
+filter 2
+rotskypos 256.75075318193080420
+dist2moon 124.2838277
+moonalt -36.1323801
+moondec -23.4960252
+moonphase 3.8193650
+moonra 256.4036553
+nsnap 2
+seqnum 0
+obshistid 230
+rottelpos 0.0000000
+seed 230
+seeing 0.8662850
+sunalt -32.7358290
+vistime 33.0000000
+# object id ra dec magnorm SED_file redshift gamma1 gamma2 kappa delta_ra delta_dec source_type length(arcsec) width(arcsec) position_angle(degrees)
+object 0 53.00913847303155535 -27.43894880881512321 16.0 starSED/phoSimMLT/lte034-4.5-1.0a+0.4.BT-Settl.spec.gz 0 0 0 0 0 0 streak 600 1e-6 0 none none

tests/test_instcat_parser.py

@@ -492,6 +492,19 @@ def test_radec_clarification(self):
             ]
         )
 
+    def test_satellite_streaks(self):
+        """Test satellite streak modeling."""
+        cat_file = os.path.join(self.data_dir, "satellite_streak.txt")
+        sed_dir = os.path.join(self.data_dir, 'test_sed_library')
+        det_name = "R22_S11"
+        wcs = self.make_wcs(instcat_file=cat_file,
+                            sensors=[det_name])[det_name]
+        cat = imsim.InstCatalog(cat_file, wcs, sed_dir=sed_dir)
+        self.assertEqual(cat.getNObjects(), 1)
+        self.assertTrue((cat.objinfo == np.array(['streak', '600', '1e-6', '0'])).all())
+        obj = cat.getObj(0)
+        self.assertTrue(isinstance(obj.original.original, galsim.Box))
+
 
 if __name__ == '__main__':
     unittest.main()