Fits2field: Add AIPS compatilibity

resolve/fits.py

@@ -64,6 +64,7 @@ def fits2field(file_name, ignore_units=False, from_wsclean=False):
         assert image_data.shape[0] == 1  # Only one Stokes component
         image_data = image_data[0]
         head = hdu_list[0].header
+        if len(set(["CUNIT1", "CUNIT2", "CUNIT3"]) & set(head.keys())) >= 1:
             assert head["CUNIT1"].strip() == "deg"
             assert head["CUNIT2"].strip() == "deg"
             assert head["CUNIT3"].strip() == "Hz"
@@ -87,7 +88,20 @@ def fits2field(file_name, ignore_units=False, from_wsclean=False):
         if not ignore_units:
             if head["BUNIT"].upper() == "JY/BEAM":
                 fac = np.pi / 4 / np.log(2)
-                scale = fac * head["BMAJ"] * head["BMIN"] * (np.pi / 180) ** 2
+
+                if "BMIN" in head:
+                    bmin, bmaj = head["BMIN"], head["BMAJ"]
+                else:
+                    def parse(lst, iden):
+                        # Can parse strings of the form:
+                        # AIPS   CLEAN BMAJ=  2.5976E-04 BMIN=  2.2344E-04 BPA= -58.25
+                        res = list(filter(lambda ll: iden in ll, lst))
+                        assert len(res) == 1
+                        res = list(filter(lambda s: s != "", res[0].split(" ")))
+                        return res[res.index(iden) + 1]
+                    bmaj = float(parse(head["HISTORY"], "BMAJ="))
+                    bmin = float(parse(head["HISTORY"], "BMIN="))
+                scale = fac * bmin * bmaj * (np.pi / 180) ** 2
             elif head["BUNIT"].upper() == "JY/PIXEL":
                 scale = abs(refs[0][2] * refs[1][2])
             else: