Fw: Ex-meridian Time Sight Fix & Air/Space
From: Bruce J. Pennino
Date: 2013 Nov 13, 17:08 -0500
Hi Frank:
I sent the attached email in response to the email
" Ex-meridian time sight fix". I guess my email is floating around in cyber
space.
More success now?
Bruce
----- Original Message -----
Sent: Tuesday, November 12, 2013 7:18 PM
Subject: Ex-meridian Time Sight Fix & Air/Space
Hello:
I was going to do the same type of analysis, but I
seem to remember that the greatest accurcacy occurs with the time sight done a
few hours (at least) before or after noon. FER wrote this not to long
ago? I was going to use some earlier recorded sight data, but never
got to it. Data with HS 15-20 degrees. Given the variation in sine
and cosine functions it makes sense that accuracy is probably quite good (not
very sensitive relatively) with the sun low in the sky. I believe it was
standard practice to do early morning and early evening sights, in the
1850s - early 1900s? I think I read this in Mixter 's Primer of
Navigation??
This past weekend we were in DC and went to
Air/Space. I spent 1 1/2 hours in "Time and Navigation". I could
have spent another hour. It is excellent and gives great credit to Weems.
Just down the hall is an excellent exhibit on "The Wright Brothers"; I also
briefly listened to an "Old Timer" ...kinda like me....discussing the Wrights,
lift/drag, etc. Also excellent! I never reached the exhibit "Pioneers of
Flight".......I must get back there when time is less pressing. I
recomend it all, very highly.
Best regards,
Bruce
----- Original Message -----
Sent: Tuesday, November 12, 2013 5:24
PM
Subject: [NavList] Ex-meridian Time Sight
Fix
I thought it would be interesting to explore the ex-meridian/time sight fix
obtained from a single observation (similar to the timed LAN and
ex-meridian/LOP). It turns out that the time sight observed near LAN is very
sensitive to the assumed latitude.. Attached is a plot that shows two time
sights. The first using the GPS latitude and the second using the ex-meridian
latitude. A 0.6' difference in the assumed latitude results in a 3' shift in
longitude.
Greg
Rudzinski
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Attached File:
:
http://fer3.com/arc/m2.aspx?i=125496
