I have this picture:
I need to determine what sidereal time it is (in hours), or how long has it been since the upper culmination of the point of the vernal equinox. How can I do that?
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I've drawn in the position of the zenith, a line from the pole star to the zenith and the position of the autumnal equinox (RA=12)
I notice that the "pointers" are on the meridian, and the pointers have a right ascension of 11hr. (I don't know the RA of all the stars, but it is easy to check with a star chart)
It is therefore 11 hours after the culmination of the vernal equinox.