# NavList:

## A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding

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Re: Happy Equinox Day
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,

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>
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?
>
>
>

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