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Venus with Earth Oblateness - 3rd time a charm?
From: Michael Dorl
Date: 2004 Oct 13, 15:09 -0500
From: Michael Dorl
Date: 2004 Oct 13, 15:09 -0500
I guess I did it again, my help desk says things should be better now.
Hopefully no html aka 'styled text'
Michael
=========
Here are the details on the calculation of TPC for Geocentric coordinates
from Mosier's
routines for Venus and the Moon
11/9/2004
11:13:05
dt = 64.4 seconds
temp = 5Cpressure 1010 MB
elevation 294M
Venus
Moon
geocentric RA 10h34m45.1022s 9h37m13.8949s
diurnal aberration 0.0076s 0.0113s
dirunal
parallax 0.3498s 2m7.3158s
refraction -5.6126s
-3.2805s
tpc RA 10h34m39.8470s 9h39m17.9415s
geocentric DECL 9d40'04.3470'" 19d29'00.7421"
diurnal aberration -0.0346" -0.0573"
diurnal
parallax -4.8748" -26'23.5639"
refraction 1'18.7829s
41.3482"
tpc
DECL 9d41'18.2205" 19d3'18.4692"
I can supply the details on the J2000 to Geocentric transformation if that
would help but I think we are agreed on the Geocentric position.
Calculating Venus/Moon Ctr/Ctr distance from TPC coordinates, one gets
16d20'22.16". Assuming Moon semi-diameter of 15'3.876" gives distance from
Venus to Moon limb of 16d05'18.284" = 16d05.3".
As far as I can tell there is nothing in the routines to allow for
oblateness of the earth. One can specify a elevation. Looks like the earth
is assumed to have a radius of 6378137 Meters, same as equatorial radius in
my 1988 AA page K6.
If I include an elevation of -9600 meters, I get a ctr/ctr distance of
16d20'25.88". Taking off a moon semi-diameter of 15'3.88" gives a ctr to
limb distance of 16d5'22" or 16d5.37' which is close to Frank's 16d5.5'. I
got the -9600 meters by considering the earth to be an oblate spheroid. I
think Mosier considers the earth to have an equatorial radius so setting
the elevation negative should compensate for the oblateness.
Michael
