NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Happy Equinox Day
From: Greg R_
Date: 2007 Mar 21, 21:29 -0700
>
> Greg R:
> > So how many of us got out today and did a LAN shot with the Sun's
> > declination close to zero?
>
> And did you take multiple sights, from a few minutes before until a
> few minutes after Local Apparent Noon, and then compare this pattern
> with the (in this case) horizontal slope?
>
>
>
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From: Greg R_
Date: 2007 Mar 21, 21:29 -0700
[Correcting the subject line, that'll teach me to
multi-task... ;-)]
> And did you take multiple sights, from a few
minutes before until a
> few minutes after Local Apparent Noon,
> few minutes after Local Apparent Noon,
Yep... started taking sights every
few minutes about 20 minutes before LAN (~20:04 UT @ 119° 20.5'
W) up to about 10 minutes after to give myself more than one "cut" at
the longitude calculation.
Managed to nail
the latitude calculation (or more likely, got really lucky... ;-)) within 0.4 NM
of the GPS position, but couldn't get a good "post-LAN" horizon kiss because the
Channel Islands were between me and the horizon at that time - so that one was
off by a few miles. Oh well... wonder if the
"dip short" method would work in that case? The islands were out near the
horizon, I'd guess 5 miles away or so.
> and then compare this pattern with the (in
this case)
> horizontal slope?
Eh? Wouldn't a graph of the sights still follow
the familiar parabolic curve leading up to and then following local noon? I
wasn't aware that the declination being almost zero would have any affect on
that (of course, the slope of the LOP *is* horizontal at meridian passage,
but that's the case any time of the year as far as I know...).
--
GregR
----- Original Message -----
From: "P F" <peter.fogg@gmail.com>
To: <NavList@fer3.com>
Sent: Wednesday, March 21, 2007 7:29
PM
Subject: [NavList 2445] Re: Happy Equpnox
Day
> Greg R:
> > So how many of us got out today and did a LAN shot with the Sun's
> > declination close to zero?
>
> And did you take multiple sights, from a few minutes before until a
> few minutes after Local Apparent Noon, and then compare this pattern
> with the (in this case) horizontal slope?
>
>
>
--~--~---------~--~----~------------~-------~--~----~
To post to this group, send email to NavList@fer3.com
To , send email to NavList-@fer3.com
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