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Hi,

I am new to this list but perhaps I can help.

The site you have visited is an astrological website and the celestial 
positions are given according to astrological conventions.

The first number is indeed the degree, followed by the zodiacal sign (Aries 
starts at 0, Taurus at 30, Gemini at 60, etc.) and then the number of 
arcminutes and arcseconds. The positions are ecliptical and appear to be 
tropical.

The R found at the end of some longitudes indicates that the planet's motion 
is retrograde (astrologers find this very important).

I hope that this helps.

Rob van Gent

-----Original Message-----
From: NavList@fer3.com [mailto:NavList@fer3.com] On Behalf Of John H
Sent: 14 September 2012 15:40
To: Gent, R.H. van (Rob)
Subject: [NavList] Zodiacal coordinates

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.




: http://fer3.com/arc/m2.aspx?i=120580

   

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