This is the first of two images taken about one month before the
planned orbit insertion of Mars Observer.  For these images, the
spacecraft was specifically maneuvered and slewed so that the planet
passed through the MOC image plane.  This image was taken at 03:52:41
UT on 27 July 1993, and was compressed by about a factor of two using
the MOC lossless predictive compressor; no processing other than
contrast enhancement has been done, and some electronic noise is
visible in the image.

This image was also released to the press; this image is in original
orientation as received, while the press release version was rotated
to put north up.  The terminator is roughly vertical here because the
spacecraft was being slewed about an axis in the plane of the
ecliptic.