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A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Sextant Positions versus Map Datums?
From: Rodney Myrvaagnes
Date: 2002 Jan 17, 1:44 PM
From: Rodney Myrvaagnes
Date: 2002 Jan 17, 1:44 PM
THe legend on the 1990 (cancelled) edition of chart 12339-- East River, Tallman Island to Queensboro Bridge, not too far from Jones Beach, say the difference from WGS84 and NAD27 iaverages 0.365" in lat and 1.509" long. THis is about 38 m as your program indicated. Way too small to be of concern except for GPS users. Chart 12334, the Upper Bay and Narrows anchorage chart. has a slightly different correction but very close. It also has dotted ticks every 5000 feet showing the New York State Grid Long Island Zone, which I suppose would connect it to Topo maps. On Thu, 17 Jan 2002 13:18:18 -0500, Jared Sherman wrote: > >Anyway...using CORPSCAN in the area of N40d 35.703m, W073d 29.596m and inputting that as NAD84, that position shifts by some 38 meters when translated to NAD27. (38 meters found by taking the offsets produced by the program and calculating the length of the diagonal.) > >And that ignores the question of whether land maps (topos) may be using various state co-o Rodney Myrvaagnes J36 Gjo/a "Religious wisdom is to wisdom as military music is to music." "What contemptible scoundrel stole the cork from my lunch?" -- W. C Fields Rodney Myrvaagnes J36 Gjo/a "Religious wisdom is to wisdom as military music is to music." "What contemptible scoundrel stole the cork from my lunch?" -- W. C Fields
