The question now is when Gienah is culminating. Allen has stated the month is May. According to the definition of right ascension 0h is the point in the sky dome which is straight above when Sun is at 'the first point in Aries' (an old misleading term when nowadays vernal equinox north of the equator is on its way to move from Pisces to Aquarius).

"Any units of angular measure can be used for right ascension, but it is customarily measured in hours (h), minutes (m), and seconds (s), with 24h being equivalent to a full circle. This is a result of the method of measuring right ascensions by timing the passage of objects across the meridian as the Earth rotates." (Wikipedia)

Thus, when Sun is at March 21 and a star is invisible behind or close to Sun the star will cross the meridian together with Sun at noon, and its right ascension must be close to 0h. We could say it has a superior culmination together with Sun in the middle of the day. The inferior culmination of the star would then be 12 hours later when it is together with Sun below Earth at midnight, when the position is nadir and not zenith.

Gienah will have a superior culmination with Sun in September 23 - it will follow Sun from dawn to evening and cross the meridian at noon. Also at the inferior culmination 12 hours later will it be invisible, this time primarily because Earth is in the way of sight.

If we change the month to March the Earth will no longer be hiding Gienah when we are looking for it in the night sky. In March both Leo and Corvus should be visible with Sun on the back side of Earth.

The meridian in the night is straight above, at zenith, and Gienah should be seen when crossing it, when culminating. We should call also such a culmination for superior because the star is straight above at zenith.

This was my theory and I needed to use the program Cartes du Ciel to verify it. In the first attempt I gave as input the date 2012-03-21 and the result was:

Corvus is not far from where it should be according to my ideas, viz. shown to be between 150º and 180º (which I assume equals 10h respectively 12h). The location of the observer is not Easter Island but the standard default value of the program, viz. 46º 13' N, 6º 9' E, and 375 m above sea level (wherever that might be).

Next I tried with May 10. Corvus has now moved well past the 180º line and is just about to leave also the line for 210º (presumably 14h):

As a last attempt I then searched for the time of the night in May 10 when Corvus was at the meridian (180º). The result was 9h 40m p.m., which expressed in minutes after midnight is 1300 (= 21 * 60 + 40). Could this be another definition of 'culmination', a definition which Allen for some reason has used?