# 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: Interesting Bowditch CelNav results was : Celestial Coordinator
From: Antoine Couëtte
Date: 2011 Dec 9, 18:57 -0800

RE :
[17580] Re: Interesting Bowditch CelNav results was ...

Kermit,

The Bowditch reductions were done with Pub. 229. Without running the numbers, I suspect that you did yours with the Law of Cosines, which could explain the difference.

Stan

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

Dear Stan,

Yes, I did use direct trig computation from each individual DR position.

Difference between computation methods here will certainly yield significantly different end results, as I have quite often observed in the past. This is one reason why - once having number crunching power at my finger tips (Thanks again to HP !!) - I totally discarted such "approximate" computations methods some 35 years ago.

I had also thought about your suggestion as being a possible explanation for the differences found between Bowditch and own results.

Can this difference between methods explain just by itself a 0.9 NM difference in the intercept of Spica (20.2 NM vs 22.1 NM)? Well, maybe, after all, but ...

... could it also "reasonably" explain a ... 6.3 NM in the intercept of Kochab (5.2 NM vs 11.5 NM) ? Would this assumption "reasonably" make sense ???

So, it looks like I am definitely missing something here.

Any help from any body, simply through running by himself the same computations ? (hint : the GMT date and time are in the morning of May 17, 1995).

Thanks in advance to who-ever will bring some light here.

Best Regards to all

Kermit

Antoine M. Couëtte

PS : For any interested "Good Samaritan", I could publish here "rearranged" computational starting data as well as end results. Although (a bit) helpful - one never knows, because this might probably be where I mistakenly understood (one of) them - the Bowditch starting data are quite self explanatory.

----------------------------------------------------------------
NavList message boards and member settings: www.fer3.com/NavList
Members may optionally receive posts by email.
To cancel email delivery, send a message to NoMail[at]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)