Fix astal crashes at high and low latitudes

Author: rrobinett

suntimes_astral2-2.py

@@ -8,5 +8,31 @@
 zone=sys.argv[3]
 l = LocationInfo('wsprep', 'local', zone, lat, lon,)
 d = date.today()
-sun=sun(l.observer, date=d, tzinfo=zone)
-print( str(sun['sunrise'])[11:16] + " " + str(sun['sunset'])[11:16] )
+#
+# Addition of try:  and except * : exception handling for use in high north and south latitudes
+# at times when the sun does not dip more than 6 deg below horizon, or rises above 6 deg below 
+# Gwyn G3ZIL 26 July 2023
+#
+# Complication is that the same exception is raised whether the sun never sets or the sun
+# rises. So look at day of year and which hemisphere in series of four ifs
+#
+# calculate day of year
+today=datetime.datetime.now()
+day_of_year=int(today.strftime('%j'))       # day of year as integer
+
+try:
+  sun=sun(l.observer, date=d, tzinfo=zone)
+  print( str(sun['sunrise'])[11:16] + " " + str(sun['sunset'])[11:16] )
+except ValueError as e:
+  if (('Sun never reaches') or ('Sun is always') in str (e)):                # exception raised
+    if (lat> 60) and (100 <= day_of_year <=260):                            # Northern hemisphere summer 
+      print('00:00 23:59')                                                   # it is light all day
+    elif (lat >60) and (1 <= day_of_year <=80 or 280 <= day_of_year <366):  # Northern hemisphere winter
+      print('00:00 00:01')                                                   # it is dark all day
+    elif (lat< -60) and (100 <= day_of_year <=260):                         # Southern hemisphere winter
+      print('00:00 00:01')                                                   # it is dark all day
+    elif (lat <-60) and (1 <= day_of_year <=80 or 280 <= day_of_year <366): # Southern hemisphere summer
+      print('00:00 23:59')                                                   # it is light all day
+    else:
+      print ('Should never get here given latitude and day of year')
+