# NavList:

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

### Compose Your Message

Message:αβγ
Message:abc
 Add Images & Files Posting Code: Name: Email:
Re: Exercise #14 Multi-Moon LOP's
Date: 2009 May 1, 16:53 -0400

```Hi Jeremy

The newly linked file method just worked.  Don't be so hard on yourself
regarding the variance in DR. S--- happens.

Upon review of the data, it shows that you are indeed subject to the SMG
estimation and not to the DR position.  That really isn't a surprise.  As
each LOP is advanced or retarded by a function of velocity, the fix changes
as a function of each LOP.  The error in SMG contributes almost directly to
the error in fix.  The same applies to the course made good.

The overall method works because of the least squares fit (assuming that is
the regression method) at the end.  This is nothing more than good old Saint
Hilaire.  We wouldn't try this on a plotting sheet, simply because all the
lines are at a relatively shallow angle.  Further, 25 LOPS with 24 advanced
LOPS might confuse the living heck out of me, especially when I go for the
"cocked hat".

However, for a computer, it is an easy day to create the fix.  It cannot be
confused by the multiplicity of lines, nor will it make a plotting error in
advancement or retardation.  Yes, a human could perform all of this, albeit
at the risk of many minor errors as they go.

For similar reasons, the Latitude by Double Altitude methods espoused by
Bowditch fell out of favor.  Just too easy to make a mistake, and very long
in computation.  This is very evident in the 4th method (variance of
declination permitted).  That method is twice as long as any other and
certainly longer than a lunar.  That makes it easy to make a mistake.  I
spent a very long time creating a spreadsheet to do this, simply because the
directions are obtuse and the cases are many.  Now that I have the method
programmed, it is easy to fill in the altitudes, declinations and time
interval.  The latitude pops out.  I would never really try this by hand, it
is just too cumbersome and error prone.

The "rapid fire fix", at least for me, falls into that category.  Yes, a
computer can perform the calculation.  A human, not so much!

Best Regards

"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
from your system. Thank you."

--~--~---------~--~----~------------~-------~--~----~
Navigation List archive: www.fer3.com/arc
To post, email 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)