NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Index checks with laser and without
From: Alexandre Eremenko
Date: 2007 Jan 03, 17:44 -0800
From: Alexandre Eremenko
Date: 2007 Jan 03, 17:44 -0800
2 days ago Bill and I tried index checks using Frank's idea with laser pointers. We used a 120 feet corridor, 3 different laser pointers 2 sextants (Astra and SNO) and 2 telescopes (Astra's native and SNO inverting). The general conclusion is that one can indeed check the IE this way, probably to 0.1' if one uses a POWERFUL scope. All our attempts to focus the laser beam using Astra's native scope at 120 feet failed. The inverting one was OK. The test gave IC=-0.4 for the SNO. Here are the results of todays Sun checks. 20 observations with filters YY: IC=-0.6 4SD=65.2(perfect) sigma=0.2 21 observations with filters RY: IC=-0.3 4SD=65.2 sigma=0.1 4 observations with a home-made telescope filter (a precious gift from a member of this list) IC=-0.5, 4SD=65.2 sigma is less than 0.1 Conclusion: some filter prizmaticity is present, probably of the R-filter, maybe both. (This confirms my earlier observations from Lunar-Sun distances that this R-filter's prizmaticity correction is about +0.2) I also did horizontal checks. All 14 vertical checks give IC=-0.4 4SD perfect, sigma=0.1 All 14 handle up checks IC=-0.5 4SD perfect, sigma=0.1 All 13 handle down checks IC=-0.5 4SD within limits (65.5) sigma=0.2 All my star checks usually fail: the results I get are inconsistent and vary between 0 and -1'. I attribute this to my night vision deterioration (I am 52), just cannot tell precisely when two star images coincide. It is better with star distances because I can rotate ("rock") my sextant. But with index rocking will not help. Alex. --~--~---------~--~----~------------~-------~--~----~ To post to this group, send email to NavList@fer3.com To , send email to NavList-@fer3.com -~----------~----~----~----~------~----~------~--~---