Force the center pixel to be the center of image

This helps ensure better consistency between the solutions. If it is not
set then astrometry.net will pick CRPIX on its own. That ensures the
headers cannot be compared, though the angular positions calculated from
the WCS should be very close.

Author: mwcraig

astroquery/astrometry_net/tests/test_astrometry_net_remote.py

@@ -67,6 +67,8 @@ def test_solve_image_upload():
     result = a.solve_from_image(image,
                                 force_image_upload=True,
                                 downsample_factor=1)
+                                downsample_factor=1,
+                                crpix_center=True)
     expected_result = fits.getheader(os.path.join(DATA_DIR,
                                                   'thumbnail-wcs-sol.fit'))
     for key in result:
@@ -111,7 +113,7 @@ def test_solve_image_detect_source_local():
                                 downsample_factor=1,
                                 fwhm=1.5, detect_threshold=5,
                                 center_ra=135.618, center_dec=49.786,
-                                radius=0.5)
+                                radius=0.5, crpix_center=True)
     expected_result = fits.getheader(os.path.join(DATA_DIR,
                                                   'thumbnail-wcs-sol-from-photutils.fit'))
     for key in result: