Fix what appears to be an off-by-one error

Author: mwcraig

astroquery/astrometry_net/core.py

@@ -441,6 +441,10 @@ def solve_from_image(self, image_file_path, *, force_image_upload=False,
             sources.reverse()
             if verbose:
                 print(sources)
+
+            # It turns out astrometry.net is 1-indexed, so add 1 to the source positions.
+            sources['xcentroid'] += 1
+            sources['ycentroid'] += 1
             return self.solve_from_source_list(sources['xcentroid'],
                                                sources['ycentroid'],
                                                ccd.header['naxis1'],