Talk:Sextant
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I have a question:
If one is to measure the height of the horizon above the imagined sea level, can you do that with a sextant?
I imagine it should be possible with something on the sextant to keep it totally horizontal.
Sverdrup 13:06, 21 Nov 2003 (UTC)
I removed extraneous information about damaged sextants, storing them, why someone shouldn't buy one without a case, etc. This is an encyclopedia article, not a product-buying guide. Alcarillo 17:20 27 Apr 2004 (UTC)
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[edit] Octant link
This article has a link to octant, which re-directs here. Anything on what to do with the link?? 66.245.121.70 02:18, 1 Dec 2004 (UTC)
The link to quadrant goes to a disam page, with no link to a relevant page. 68.1.98.64 04:01, 11 December 2006 (UTC)
[edit] Pilotage, horizontal angles etc
A sextant is not exclusively used to measure angles between a celestial object and the horizon. As many sailors know, it is also used to measure angles between two landmarks by placing it horizontaly. This can be very helpful in determining one's position at sea in coastal navigation, if one has a Chart, of course. --Jprats
You can also use it (the normal way up) to measure distance-off by measuring the angular height of an object like a lighthouse (if the real height is known and corrections are made for the current height of the tide). I've been wondering whether to put these ideas into here or into Pilotage. We can do something here about these present day, modern uses of the sextant in pilotage, as well as as a backup for the day when the GPS system or your own GPS receiver(s) pack up while you're at sea. It's not just a historical novelty. --Nigelj 11:26, 6 August 2005 (UTC)
[edit] Sextant
[edit] when?
Okay, I was doing a research project and I was just trying to figure out what time period sectants were used. I can't find it. It says something about 1730, but is that when they were used. I read somewhere about the Elizabethan era. Ahhh, I don't know anything about them. jess523s 23:34, 30 April 2006 (UTC)
[edit] Approximate vs. Precise
The reason I changed "precise location" to "approximate location" is that the use of a Line of Position (LOP) from a sextant reading is approximate, and the LOP from dead reckoning is likewise approximate. Stating "precise position" is implying something a little more specific. Generally, if you can establish your position within 1-3 miles of actual position you're doing pretty good. (unsigned comment by User:Quartermaster)
I changed it to just plain "fix". All fixes are approximate. A sextant fix might be good to a couple of miles, a GPS fix to a few yards, but they're both approximate. Calling something "precise" is almost meaningless unless you specify the numeric uncertainty. -- RoySmith (talk) 19:08, 21 May 2006 (UTC)
The question is now do we use the appropriate and relevant jargon "location fix" without linking to an explanation that all fixes are approximate. We're agreed that a celestial LOP and dead reckoning position are not precise. No position is precise, but a fix determined by celestial navigation within 1 mile is considered excellent, hence, the overriding need to delete the term "precise" here, which has been done.
How about a change that states "The intersection of that circle with a dead reckoning track, or another sighting yields a location fix (approximate location)." That way we use the appropriate vocabulary for the topic (location fix) but parenthetically clarify it to the casual Wikipedia user. Ideally, we would point to an entry explaining "location fix," but at least the "See also" links to celestial navigation and navigation would clarify things for the thorough and curious. Quartermaster.
[edit] illustrations
I think that this article could use some diagramatic illustrations elxplaining the layout and principle of a sextants operation. ike9898 04:10, 28 October 2006 (UTC)
