Add observation_reason property

python/astro_metadata_translator/properties.py

@@ -82,6 +82,9 @@
               "observation_id": ("Label uniquely identifying this observation "
                                  "(can be related to 'exposure_id').",
                                  "str", str),
+              "observation_reason": ("Reason this observation was taken, or its purpose ('science' and "
+                                     "'calibration' are common values)",
+                                     "str", str),
               "exposure_group": ("Label to use to associate this exposure with others "
                                  "(can be related to 'exposure_id').",
                                  "str", str),

python/astro_metadata_translator/translator.py

@@ -789,6 +789,24 @@ def to_exposure_group(self):
         else:
             return str(exposure_id)
 
+    @cache_translation
+    def to_observation_reason(self):
+        """Return the reason this observation was taken.
+
+        Base class implementation returns the ``science`` if the
+        ``observation_type`` is science, else ``unknown``.
+        A subclass may do something different.
+
+        Returns
+        -------
+        name : `str`
+            The reason for this observation.
+        """
+        obstype = self.to_observation_type()
+        if obstype == "science":
+            return "science"
+        return "unknown"
+
 
 def _make_abstract_translator_method(property, doc, return_typedoc, return_type):
     """Create a an abstract translation method for this property.

tests/test_cfht.py

@@ -40,6 +40,7 @@ def test_megaprime_translator(self):
                            object="w2.+2+2",
                            observation_id="1038843",
                            observation_type="science",
+                           observation_reason="science",
                            physical_filter="i.MP9702",
                            pressure=617.65*u.hPa,
                            relative_humidity=39.77,
@@ -64,6 +65,7 @@ def test_megaprime_translator(self):
                            object="D3",
                            observation_id="849375",
                            observation_type="science",
+                           observation_reason="science",
                            physical_filter="r",
                            pressure=615.79*u.hPa,
                            relative_humidity=15.76,

tests/test_decam.py

@@ -39,6 +39,7 @@ def test_decam_translator(self):
                            object="DES supernova hex SN-S1 tiling 22",
                            observation_id="ct4m20130901t060255",
                            observation_type="science",
+                           observation_reason="science",
                            physical_filter="z DECam SDSS c0004 9260.0 1520.0",
                            pressure=779.0*u.hPa,
                            relative_humidity=23.0,
@@ -64,6 +65,7 @@ def test_decam_translator(self):
                            object="postflats-BIAS",
                            observation_id="ct4m20121211t220632",
                            observation_type="zero",
+                           observation_reason="unknown",
                            physical_filter="Y DECam c0005 10095.0 1130.0",
                            pressure=777.0*u.hPa,
                            relative_humidity=38.0,
@@ -89,6 +91,7 @@ def test_decam_translator(self):
                            object="Blind15A_03",
                            observation_id="ct4m20150220t004721",
                            observation_type="science",
+                           observation_reason="science",
                            physical_filter="g",
                            pressure=777.0*u.hPa,
                            relative_humidity=76.0,
@@ -114,6 +117,7 @@ def test_decam_translator(self):
                            object="",
                            observation_id="ct4m20190402t050618",
                            observation_type="science",
+                           observation_reason="science",
                            physical_filter="VR DECam c0007 6300.0 2600.0",
                            pressure=779.0*u.hPa,
                            relative_humidity=38.0,

tests/test_sdss.py

@@ -39,6 +39,7 @@ def test_sdss_translator(self):
                            object="82 S",
                            observation_id="6377 4 g 407",
                            observation_type="science",
+                           observation_reason="science",
                            physical_filter="g",
                            pressure=None,
                            relative_humidity=None,

tests/test_subaru.py

@@ -39,6 +39,7 @@ def test_hsc_translator(self):
                            object="STRIPE82L",
                            observation_id="HSCA90402400",
                            observation_type="science",
+                           observation_reason="science",
                            physical_filter="HSC-I",
                            pressure=621.7*u.hPa,
                            relative_humidity=33.1,
@@ -62,6 +63,7 @@ def test_hsc_translator(self):
                            object="SSP-Wide",
                            observation_id="HSCA04090000",
                            observation_type="science",
+                           observation_reason="science",
                            physical_filter="HSC-R",
                            pressure=625.4*u.hPa,
                            relative_humidity=8.6,
@@ -93,6 +95,7 @@ def test_suprimecam_translator(self):
                            object="Ecliptic Deep Field",
                            observation_id="SUPE00535770",
                            observation_type="science",
+                           observation_reason="science",
                            physical_filter="W-S-R+",
                            pressure=621.5*u.hPa,
                            relative_humidity=4.9,