This shows the alignment of USNO-A2.0 Stars with a test image before the
world coordinate system has been fit. The coordinates plotted are based
on the telescope pointing direction (RA and DEC in the image header),
the image plate scale (SECPIX in the image header), and the image size
(NAXIS1 and in the image header.
[Image with Nominal WCS]
[Image with Fit WCS]