Ensure external sky maps are normalized

CHANGES.rst

@@ -50,6 +50,8 @@ Changelog
 
 -   Add platform and hostname information to the Flask dashboard.
 
+-   Ensure external sky maps are normalized.
+
 0.12.3 (2020-03-24)
 -------------------
 

gwcelery/tasks/external_skymaps.py

@@ -285,7 +285,8 @@ def create_external_skymap(ra, dec, error, pipeline, notice_type=111):
             weight * hp.sphtfunc.smoothing(skymap, sigma=np.radians(scale))
             for weight, scale in zip(weights, scales))
 
-    return skymap
+    # Renormalize due to possible lack of precision
+    return skymap / skymap.sum()
 
 
 def write_to_fits(skymap, event, notice_type, notice_date):

gwcelery/tests/test_tasks_external_skymaps.py

 from importlib import resources
 from unittest.mock import patch
 
+import numpy as np
 import pytest
 
 from . import data
@@ -150,7 +151,9 @@ def test_create_swift_skymap(ra, dec, error, pix):
 def test_create_fermi_skymap():
     """Test created single pixel sky maps for Swift localization."""
     ra, dec, error = 0, 90, 10
-    external_skymaps.create_external_skymap(ra, dec, error, 'Fermi')
+    assert (np.sum(external_skymaps.create_external_skymap(
+               ra, dec, error, 'Fermi')) ==
+           pytest.approx(1.0, 1.e-9))
 
 
 @patch('gwcelery.tasks.gracedb.upload.run')