NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: Greg Rudzinski
Date: 2013 Mar 17, 16:43 -0700
Alan,
Arc Sin [ (Cos 29.5533)(Sin 46.2733) / Cos 31.2266 = 47.3* = Z
180* + 47.3* = 227.3* azimuth
Seems to be the same as USNO
Greg Rudzinski
Azimuth discrepancy?
From: Alan S
Date: 2013 Mar 17, 16:06 -0700
Using Jeremy's raw sextant data for Fomalhaut, on 13 January, 2013, listed in his March post as follows:
Watch Time: 19:12:24
Hs: 31D 19,9M
Height of Eye: 83'
Index Error: 0.9 On Arc
ZD: -8
DR: 08D 50.0M North x 109D 40.0M East
Temp: 80D F.
Bar. Press.: 1013MB HG
Using the 2013 Commercial edition Nautical Almanac Daily Pages and LOC Method for Sight Reduction, I got the following:
LHA: 46D 16.4M
Ho: 31D 09.9M
Hc: 31D 13.6M
Dec: 29D 33.2 South
a: 3.7 NM Away
Zn 240D
I made no adjustment for temp. or pressure.
The above results seem ""Kosher"".
Using U.S. Naval Observatory Gastronomic Applications Department Celestial Navigation Data, for the time, date and DR coordinates given, I got the following results:
GHA: 296D 36.5
Dec.: 29D 33.2M South
Hc: +31D 13.5M
Zn: 227.3D, call it 227D
Differences in GHA, Hc and Dec, being 0.1M seem minor, however a difference of 13 D in Zn seems significant and leaves me curious. Clarification or explanation please.
----------------------------------------------------------------
NavList message boards and member settings: www.fer3.com/NavList
Members may optionally receive posts by email.
To cancel email delivery, send a message to NoMail[at]fer3.com
----------------------------------------------------------------