diff --git a/LICENSE b/LICENSE
index fd4afaf..ba48312 100644
--- a/LICENSE
+++ b/LICENSE
@@ -1,6 +1,6 @@
 MIT License
 
-Copyright (c) 2018 Michael Kelley
+Copyright (c) 2018-2019 University of Maryland and the calviacat contributors
 
 Permission is hereby granted, free of charge, to any person obtaining a copy
 of this software and associated documentation files (the "Software"), to deal
diff --git a/README.md b/README.md
index 96d3657..48df092 100644
--- a/README.md
+++ b/README.md
@@ -1,6 +1,10 @@
-# calviacat v1.0.1
+# calviacat v1.0.2
 Calibrate star photometry by comparison to a catalog.  PanSTARRS 1 and SkyMapper catalogs currently implemented.  Catalog queries are cached so that subsequent calibrations of the same or similar fields can be more quickly executed.
 
+## Attribution and license
+
+calviacat is written by Michael S. P. Kelley, with contributions from: Tim Lister.  It is licensed with the MIT License (see LICENSE for details).
+
 ## Requirements
 
 * sqlite3
diff --git a/calviacat/catalog.py b/calviacat/catalog.py
index b4ca92f..dd0156b 100644
--- a/calviacat/catalog.py
+++ b/calviacat/catalog.py
@@ -13,7 +13,16 @@
 from astropy.coordinates import SkyCoord
 from astropy.stats import sigma_clipped_stats, sigma_clip
 from astropy.modeling import models, fitting
-from astropy.version import version_info as astropy_version
+
+try:
+    from astropy.version import version_info as astropy_version
+except ImportError:
+    import astropy.version
+    astropy_version = [int(x) for x in astropy.version.version.split('.')]
+
+
+class CalibrationError(Exception):
+    pass
 
 
 class TableDefinition:
@@ -418,10 +427,16 @@ def cal_color(self, matched, m_inst, filt, color, C=None,
             fitting.LinearLSQFitter(), sigma_clip)
 
         i = np.isfinite(dm) * ~dm.mask
-        if astropy_version[0] > 3 or (astropy_version[0] == 3 and astropy_version[1] >= 1):
-            # Return order changed in astropy 3.1 (http://docs.astropy.org/en/stable/changelog.html#id10)
-            # Also now returns a boolean mask array rather than a MaskedArray of the data which could
-            # be applied back to reconstuct 'line' if needed (not currently used)
+        if sum(i) == 0:
+            raise CalibrationError('All sources masked.')
+
+        if (astropy_version[0] > 3 or
+                (astropy_version[0] == 3 and astropy_version[1] >= 1)):
+            # Return order changed in astropy 3.1
+            # (http://docs.astropy.org/en/stable/changelog.html#id10)
+            # Also now returns a boolean mask array rather than a
+            # MaskedArray of the data which could be applied back to
+            # reconstuct 'line' if needed (not currently used)
             fit, mask = fitter(model, cindex[i], dm[i])
         else:
             line, fit = fitter(model, cindex[i], dm[i])
diff --git a/setup.py b/setup.py
index 4e8158b..cdedec0 100755
--- a/setup.py
+++ b/setup.py
@@ -3,7 +3,7 @@
 from distutils.core import setup
 
 setup(name='calviacat',
-      version='1.0.1',
+      version='1.0.2',
       description='Calibrate star photometry by comparison to a catalog.',
       author='Michael S. P. Kelley',
       author_email='msk@astro.umd.edu',