# NavList:

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

Message:αβγ
Message:abc
 Add Images & Files Posting Code: Name: Email:
Re: Lunar longitudes, not by lunar distance. Was- Re: Working a lunar
Date: 2009 Aug 7, 12:23 -0400

```Hang on George,

Hanno has required that the moon and the other object be ON the meridian at
different times, and that the delta time between those meridian passages be
the key component.

I agree with your statement that it is the same for everybody on earth, should
that delta time not include the meridian passage.

Once the meridian passage is included however, then only ONE meridian has that
precise delta time, the meridian of observation.  As the earth rotates and
the moon changes position, then the delta time will change.

At your meridian in the UK, the delta time will be X.  By the time those same
objects individually CROSS MY MERIDIAN in the US, about 5 hours later, the
position of the moon will change by about 2.5 degrees.  Thus the delta time
between those objects on my meridian will be different!

Anyone on your meridian, independent of latitude and under the assumption that
they can see them, will get the same delta time.

Best Regards

-----Original Message-----
From: NavList@fer3.com [mailto:NavList@fer3.com] On Behalf Of George Huxtable
Sent: Friday, August 07, 2009 11:07 AM
To: NavList@fer3.com
Subject: [NavList 9402] Lunar longitudes, not by lunar distance. Was- [NavList 9393] Re: Working a lunar

Hanno Ix wrote, in 9382,

If I see things right, there must be a LOP which connects all locations
on Earth with a given, fixed difference DT between the meridian
passages of sun and moon.

What I meant is:

If I see things right, there must be a LOP which connects all those
locations
on Earth that have a given, fixed difference DT between the meridian
passages of sun and moon.

================

Is there woolly thinking here, I wonder?

Wherever on Earth the Moon is seen from, it's phase is the same except for
the effects of parallax, which can be corrected for. At Full Moon, it's
always very nearly 180 � from the Sun. So that's the Sun's lunar distance,
which is the same wherever on Earth it's observed from. And then the time
difference between meridian passages of Sun and Moon is 12 hours, the whole
World over. The phase of the Moon, the lunar distance, and the time
difference between meridian passages, change in step, going through a whole
cycle in a month, and at any moment in the month all are the same wherever
on Earth they are observed from. Measuring a lunar distance, or the time
between meridian passage (or even the phase, if it was possible to do that
precisely), all provide the same message: the time of the month. From that
time of the month, from the nautical tables, we could deduce the day (if
that was needed) or, more importantly, the time-of-day, in terms of GMT. It
by comparing that GMT with the local time that we deduce the longitude.

There's no "LOP which connects all those locations on Earth that have a
given, fixed difference DT between the meridian passages of sun and moon."
At any moment that DT is the same everywhere.

George.

contact George Huxtable, at  george{at}hux.me.uk
or at +44 1865 820222 (from UK, 01865 820222)
or at 1 Sandy Lane, Southmoor, Abingdon, Oxon OX13 5HX, UK.

"Confidentiality and Privilege Notice
The information transmitted by this electronic mail (and any attachments) is
being sent by or on behalf of Tactronics; it is intended for the exclusive
use of the addressee named above and may constitute information that is
privileged or confidential or otherwise legally exempt from disclosure. If
you are not the addressee or an employee or agent responsible for delivering
this message to same, you are not authorized to retain, read, copy or
disseminate this electronic mail (or any attachments) or any part thereof. If
you have received this electronic mail (and any attachments) in error, please
call us immediately and send written confirmation that same has been deleted

--~--~---------~--~----~------------~-------~--~----~
NavList message boards: www.fer3.com/arc
Or post by email to: NavList@fer3.com
To unsubscribe, email NavList-unsubscribe@fer3.com
-~----------~----~----~----~------~----~------~--~---

```
Browse Files

Drop Files

### Join NavList

 Name: (please, no nicknames or handles) Email:
 Do you want to receive all group messages by email? Yes No
You can also join by posting. Your first on-topic post automatically makes you a member.

### Posting Code

Enter the email address associated with your NavList messages. Your posting code will be emailed to you immediately.
 Email:

### Email Settings

 Posting Code:

### Custom Index

 Subject: Author: Start date: (yyyymm dd) End date: (yyyymm dd)