Addition of re-projection to a common observer

arccnet/utils/transformations.py

@@ -0,0 +1,59 @@
+import sunpy.map
+from sunpy.coordinates.frames import HeliographicStonyhurst
+
+from astropy import units as u
+from astropy.coordinates import SkyCoord
+
+
+def reproject_instrument(
+    sunpy_map: sunpy.map.Map,
+    radius: u.Quantity = 1 * u.au,
+    scale: u.Quantity = u.Quantity([0.5, 0.5], u.arcsec / u.pixel),
+):
+    """
+    Reproject a `sunpy.map.Map` to a new observer location with a specified radius and plate scale.
+
+    Parameters:
+    -----------
+    sunpy_map : `sunpy.map.Map`
+        The input map to be reprojected.
+
+    radius : `astropy.units.quantity.Quantity`, optional
+        The radius at which the new observer is located. Default is 1 astronomical unit (1*u.au).
+
+    scale : `astropy.units.quantity.Quantity`, optional
+        The plate scale of the output map. Default is [0.5, 0.5] arcsec per pixel.
+
+    Returns:
+    --------
+    out_map : `sunpy.map.Map`
+        The reprojected map with the specified observer location, radius, and plate scale.
+
+    """
+
+    original_observer = sunpy_map.reference_coordinate.frame.observer
+
+    new_observer = SkyCoord(
+        0 * u.arcsec,
+        0 * u.arcsec,
+        frame="helioprojective",
+        rsun=sunpy_map.reference_coordinate.rsun,
+        obstime=original_observer.obstime,
+        observer=HeliographicStonyhurst(
+            original_observer.lon,
+            original_observer.lat,
+            radius,
+            obstime=original_observer.obstime,
+            rsun=original_observer.rsun,
+        ),
+    )
+
+    out_header = sunpy.map.make_fitswcs_header(
+        sunpy_map.data.shape,
+        new_observer,
+        scale=scale,
+    )
+
+    out_map = sunpy_map.reproject_to(out_header)
+
+    return out_map