NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: Byron Franklin
Date: 2013 Jan 14, 09:03 -0800
Byron: The horizon Disk can be place at the correct Lat & Long.
Not only the over-head but the accuracy near the Horizon is very good. The shape of the Horizon and AZ& HT change very little with a small change of Lat. Say 45 placed at 41. It's the placement of the 10 degree jump of the 2102-D that hurts.The change in the stars SHA & Dec for the Star Disk will be good for our life time ++++++.
To find the GMT of any set up, occurrence, you need only - the M&D GMT.
Time of Sunrise/ Set can be placed on the star disk by NA. SR, local newspaper, I did compare they were with-in one minute. Jan 12th news=07:12 NA=07:11 GMT 07:12+5=GMT 12:12.
I Got the GMT for that Month & day Jan 12=19:28 add the GMT12:12 of paper SR.=31:40-24=07;40 Place Aries @ 07:40 Next run a line from the Pole to the GMT 07:40. Place Aries on the outer base plate07:40. The stars are in their correct position. Run a straight edge from the pole to the GMT of sun rise 12:12 on the base disk. The sun is on the horizon and this line. Marks the sun on the star disk at the horizon with a grease pencil, read the amp bearing. 117 You can than track the sun across you sky.
I also checked this sun position on the horizon by Pole Distance. DEC was 22S + 90 =112 degrees, an arc from the Pole passes the horizon on the same 117 degrees.
This took me less than 2 minutes set up.
I checked the accuracy. The stars were < 2 degrees in AZ & HT. LAN Finder 16:46 HT 27,AZ 180.
The compute LAN was 16:47 HT 27 AZ178.
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