Subject: topozone upgrade permits federal maritime tripointing down to degminsecs<br/>
Date: Feb 24, 2004 @ 16:58<br/>
Author: Michael Donner (&quot;Michael Donner&quot; &lt;barbaria_longa@...&gt;)<br/>
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<br/><br/>
<div id="ygrps-yiv-1370356034">actually several pleasant surprises this morning at topozone<br/>
<br/>
first<br/>
the long awaited topos of puerto rico & the virgin islands are finally being <br/>
filled in<br/>
& are now practically complete on at least one coverage level<br/>
<br/>
second<br/>
it is apparently now possible to use the coordinate format feature there to <br/>
get geopositions down to the nearest integral degminsecs<br/>
by simply clicking on any desired point<br/>
wow<br/>
& i say apparently only because i have previously found that the purported <br/>
accuracy levels of topozone may leave something to be desired<br/>
<br/>
but whatever the actual range of error here of each stated second of <br/>
latitude & longitude<br/>
we are now surely within a few hundred feet & hopefully within 100 feet of <br/>
the truth<br/>
even while we realize that the truth of the maritime tripoints will be <br/>
elusive in any case for a host of other reasons too<br/>
<br/>
<br/>
but at last we do have the means to at least try for the exact degminsecs<br/>
<br/>
<br/>
so in view of the above 2 discoveries<br/>
i immediately & excitedly tried for the 2 most difficult & problematic of <br/>
the 20 tripoints in this maritime category<br/>
prusvin & prusvis<br/>
which you may recall were last revisited in<br/>
<a rel="nofollow" target="_blank" href="http://groups.yahoo.com/group/BoundaryPoint/message/12670">http://groups.yahoo.com/group/BoundaryPoint/message/12670</a><br/>
<br/>
<br/>
now<br/>
tho i couldnt be absolutely sure that the maps provided by topozone actually <br/>
included the easternmost islands of the puerto rico group & the westernmost <br/>
of the virgin islands group<br/>
it does seem likely that<br/>
<a rel="nofollow" target="_blank" href="http://www.topozone.com/map.asp?lat=18.3185&lon=-65.225">http://www.topozone.com/map.asp?lat=18.3185&lon=-65.225</a><br/>
shows the base points on isla culebrita for the eastwardmost projections of <br/>
the 3league limits of puerto rico<br/>
namely<br/>
cabo del pasaje for the northeastwardmost arc<br/>
& the islet just southeast of punta del este for the southeastwardmost<br/>
<br/>
& if you zoom this swatch all the way out to 1000000k<br/>
you will see where these points are in relation to all the easternmost <br/>
islands of puerto rico<br/>
including the entire culebra group & vieques etc<br/>
& indeed in relation to the northeast coast of puerto rico itself<br/>
as well as in relation to the westernmost of the virgin islands<br/>
<br/>
& you will also see the virgin passage that lies between these 2 groupings<br/>
& where both of the tripoints will fall<br/>
on the atlantic & caribbean sides respectively of this passage<br/>
& actually within the area indicated in black there rather than blue<br/>
owing to the nonexistence of topos of the open sea<br/>
<br/>
<br/>
& proceeding next into similar detail on the virgin side<br/>
it seems similarly likely that the basepoints for the westwardmost <br/>
projections of the 3mile limits are<br/>
<a rel="nofollow" target="_blank" href="http://www.topozone.com/map.asp?lat=18.33778&lon=-65.08528">http://www.topozone.com/map.asp?lat=18.33778&lon=-65.08528</a><br/>
on one hand<br/>
for the southwesterly arc based on the islet just southeast of virgin point <br/>
on savana island<br/>
&<br/>
<a rel="nofollow" target="_blank" href="http://www.topozone.com/map.asp?lat=18.40583&lon=-65.06083">http://www.topozone.com/map.asp?lat=18.40583&lon=-65.06083</a><br/>
on the other hand<br/>
for the northwesterly arc based on the islet just west of cockroach island<br/>
<br/>
& btw you can again find your place if necessary by zooming all the way out <br/>
here too<br/>
<br/>
<br/>
so after clicking as carefully as possible on all 4 of these relevant base <br/>
points to get their best available degminsecs<br/>
i then mapped these points on graph paper & ran some trial arcs out from <br/>
them<br/>
at the respective 9nm & 3nm radii<br/>
in order to get rough positions for the 2 arc intersections<br/>
<br/>
<br/>
then with the help of this great circle calculation site<br/>
<a rel="nofollow" target="_blank" href="http://www.wcrl.ars.usda.gov/cec/java/lat-long.htm">http://www.wcrl.ars.usda.gov/cec/java/lat-long.htm</a><br/>
i was able to check & improve the accuracy of my intersection projections<br/>
thru 6 more trials in each case in fact<br/>
until i finally reached fully coordinated positions of<br/>
nlat 18d25m46s x wlong 65d06m35s<br/>
or about 3nm wnw of cockroach island<br/>
for prusvin<br/>
&<br/>
nlat 18d17m29s x wlong 65d03m53s<br/>
or about 3nm actually sse of savana island<br/>
for prusvis<br/>
<br/>
<br/>
as for the best available pics<br/>
these are only for prusvin<br/>
& probably only class e<br/>
<a rel="nofollow" target="_blank" href="http://www.vacationrentalsonline.com/vr/st/st1006/st1006.htm">http://www.vacationrentalsonline.com/vr/st/st1006/st1006.htm</a><br/>
with nothing at all yet for prusvis<br/>
<br/>
<br/>
but anyway<br/>
with both of these most difficult positions finally in hand<br/>
& with the considerable help already provided by lowell too<br/>
it should now be comparatively easy to find & zero in on the remaining 18 <br/>
maritime tripoints of the usa down to the same level of accuracy<br/>
<br/>
then we could scarf up pix not only of but actually from all 20 of these <br/>
tripoints on a single continuous cruise<br/>
<br/>
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