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    Zodiacal coordinates
    From: John Huth
    Date: 2012 Sep 14, 09:38 -0400


    I was hoping someone could help me decipher reports in ephemerides of celestial positions.   I know how to cope with right ascension and declination.   

    Where I get stuck is in the report of "longitude" and "latitude".    I'm using the site:

    http://www.ephemeris.com/ephemeris.php

    A typical entry is shown below.

    I'm assuming from inspection that "longitude" and "latitude" are based on an ecliptic/zodiacal coordinate system.   It seems, again from inspection, that the zero of latitude is taken as the the ecliptic.   What I don't understand is the notation for longitude.   There is a leading number, which I don't understand, followed by a zodiacal sign and then a number in minutes and seconds.   I'm assuming that the leading notation is some number of degrees, but I'm unsure.

    If this is the case, I see that all the numbers are positive - that indicates some 'handedness' to the notation - that the zero starts at some boundary of a zodiacal sign, but then, what determines the convention?   Is it tropical or sidereal?  Since one only sees the classical zodiac in these tables, I'm assuming that it doesn't correspond to the IAU convention.   

    Clearly there must be a convention somewhere for reporting these, but I just can't seem to put my hands on it.

    If someone has any pointers as to where to look, I'd be most grateful.


    Planet     Longitude Latitude    RA Decl

    Venus                 24 Lib 37'25"           0°27'23"          13:31:54         - 9°06'59"


    John H. 

       
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