This illusive feature lies just north of Fra Mauro and Parry (With an "A") crater on the edge of the Mare Cognitum region. If the Fra Mauro region sounds familiar, that's because it was the site slated for the aborted Apollo 13 landing, which was eventually performed on Apollo 14. Read more
The Curtiss Cross (IAU designation "Fra Mauro Zeta"), an X-shaped illumination effect similar to the first quarter lunar X on the moon, can be seen at ~10:30 UT, 31st July, (just past Last Quarter Moon) between the Parry and Gambart craters in the Fra Mauro region