Hi Greg, The east-west equivalent of the meridian is called the prime vertical. W. Chauvenet's Manual of Spherical and Practical Astronomy (1863) notes that it is very useful for determining an observer's latitude.
The method involves setting up a transit instrument in the prime vertical, then timing when a star crosses it in the east and later in the west. Chauvenet speaks of a star's "transits over the vertical circle." -- Roger ----- Original Message ----- From: "Greg Gómez" <[email protected]> To: <[email protected]> Sent: Wednesday, January 14, 2009 12:29 PM Subject: East/West "meridian?" > > Hello: > > The last full moon I was taking a walk and was marveling that when the > moon is near it's northern extreme, it is quite high when it crosses 90 > degrees azimuth. > > A question occurred to me: > Is there an east/west equivalent to the meridian? In other words, what > is the term for the great circle that goes through azimuth 90 and 180 > degrees and through the zenith? > > Also, is there a term for when an object crosses that line? > > Thanks! > Greg > > > > > > --------------------------------------------------- > https://lists.uni-koeln.de/mailman/listinfo/sundial > > --------------------------------------------------- https://lists.uni-koeln.de/mailman/listinfo/sundial
