To make these images I used the command:
% SimIm1 Y Y
The second argument if the flip parameter that indicates I am flipping the image about
the Y axis. The original image is in the left panel, and the flipped image is in the
right panel. The RED line is a 1 arcmin segment that points NORTH, and the YELLOW line
is a 0.5 arcmin segment that points EAST. Here are the WCS cards installed in the
transformed (right) image:
CTYPE1 = 'RA---TAN' / Gnomonic Projection
CTYPE2 = 'DEC--TAN' / Gnomonic Projection
CRPIX1 = 100.000 / Axis 1 Reference
CRPIX2 = 100.000 / Axis 2 Reference
CRVAL1 = 180.000000000 / Ra at Frame, J2000 (deg)
CRVAL2 = 32.500000000 / Dec at Frame, J2000 (deg)
CROTA2 = 0.000000000000 / Image Twist +AXIS2 W of N, (deg)
CDELT1 = 0.0002777777845 / Axis 1 Pixel Size (degs)
CDELT2 = 0.0002777777845 / Axis 2 Pixel Size (degs)
CRVALE = 50.000 / Combined CRVAL error (arcsec)
Notice that I have higlighted the CDELT1 value to stress that all I have
done for this Y-axis flip and change the sign of CDELT1. Compare this header
to the previous header example in SimIm0.
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