Wrap sci PA to the range -30 to 30 degrees.

src/gort/gort.py

@@ -54,6 +54,7 @@
     run_in_executor,
     set_tile_status,
 )
+from gort.transforms import wrap_pa_hex
 
 
 if TYPE_CHECKING:
@@ -851,6 +852,12 @@ async def observe_tile(
         if adjust_focus:
             await self.guiders.adjust_focus()
 
+        # Wrap the PA to the range -30 to 30.
+        new_pa = wrap_pa_hex(tile.sci_coords.pa)
+        if new_pa != tile.sci_coords.pa:
+            self.log.debug(f"Wrapping sci PA from {tile.sci_coords.pa} to {new_pa}.")
+            tile.sci_coords.pa = new_pa
+
         if tile.tile_id is not None:
             dither_positions_str = ", ".join(map(str, dither_positions))
             self.log.info(

src/gort/transforms.py

@@ -35,6 +35,7 @@
     "Siderostat",
     "HomTrans",
     "Mirror",
+    "wrap_pa_hex",
 ]
 
 
@@ -421,6 +422,34 @@ def calculate_field_angle(
     return siderostat.field_angle(target, time=obstime)
 
 
+def wrap_pa_hex(pa: float):
+    """Wraps a position angle to the range -30 to 30 degrees.
+
+    Parameters
+    ----------
+    pa
+        The position angle to wrap. Always in degrees in the range 0 to infinity.
+
+    Returns
+    -------
+    pa_wrap
+        The wrapped position angle in the range -30 to 30 degrees.
+
+    """
+
+    # First convert to the range 0 to 360 degrees.
+    pa = pa % 360
+
+    # Then wrap to the range 0 to 60 degrees to account for the IFU hexagonal symmetry.
+    pa = pa % 60
+
+    # Finally, wrap to the range -30 to 30 degrees.
+    if pa > 30:
+        pa -= 60
+
+    return pa
+
+
 class Siderostat:
     """A siderostat of 2 mirrors.