Merge pull request #295 from lsst/tickets/DM-29187

DM-29187: Do not fix RASTART header for LATISS after 2021-02-12

python/lsst/obs/lsst/translators/latiss.py

@@ -62,6 +62,9 @@
 # instead of degrees.
 RASTART_IS_HOURS = Time("2021-02-11T18:45", format="isot", scale="utc")
 
+# From this date RASTART is correct as-is.
+RASTART_IS_OKAY = Time("2021-02-12T00:00", format="isot", scale="utc")
+
 # DATE-END is not to be trusted before this date
 DATE_END_IS_BAD = Time("2020-02-01T00:00", format="isot", scale="utc")
 
@@ -378,9 +381,9 @@ def fix_header(cls, header, instrument, obsid, filename=None):
                 modified = True
 
         # RASTART/END headers have a TAI/UTC confusion causing an offset
-        # of 37 seconds. Once this is fixed in the acquisition system
-        # the correction will have an upper date bound.
-        if date > RASTART_IS_BAD:
+        # of 37 seconds for a period of time.
+        if RASTART_IS_BAD < date < RASTART_IS_OKAY:
+            modified = True
             offset = (37.0 / 3600.0) * 15.0
             for epoch in ("START", "END"):
                 h = "RA" + epoch

tests/test_translator.py

@@ -852,14 +852,15 @@ def test_fix_header(self):
         # Not all headers are used in metadata translation
         test_data = (
             ("latiss-AT_O_20210212_000006.yaml",
-             dict(RASTART=260.1785517385836)),
+             dict(RASTART=260.024385071917)),
             ("latiss-AT_O_20210210_000011.yaml",
              dict(RASTART=355.41750341182313)),
         )
         for filename, expected in test_data:
             with self.subTest(f"Testing {filename}"):
                 header = read_test_file(filename, dir=self.datadir)
-                fix_header(header)
+                modified = fix_header(header)
+                self.assertTrue(modified)
                 for k, v in expected.items():
                     self.assertEqual(header[k], v, f"Testing {k} in {filename}")