Here's and odd question- does it matter whether you use the column for minutes of declination or "d" correction from Pub. No. 249 to get the proper "d" correction?  By this I mean I've discovered that whether 249 specifies any "d" correction (45 for example) and the Sun's declination for a certain day and time (let's just say 21 minutes of declination) the same correction value of 16 can be found whether you use 45 minutes of declination and a "d" of 21 or 21 minutes of declination and a "d" value of 45.  No matter which way you  arrange it you still get a d correction of 16.

That would let me think that Table 5 is goof proof- you'll still get the same d correction value.

What do you think?

Thanks,

Ed


TABLE 5- Correction to Tabulated Altitude for Minutes of Declination

I was brushing up on the procedure for figuring the great circle route, the one in the 50 year almanac by Kolbe and had some troubles. Maybe  I was just tired and the tv was on but 2 attempts at fairly close destinations, both under 400 NM just didn't work. Once I chose someplace more distant, about 2900 NM it worked fine. Is it possible to be too close to use? TIA

Greetings, 

I tried to to use intercept method in solving some problems from a book and found out that despite the fact that Polaris is one of the most easily recognizable stars in the Northern Hemisphere Nautical Almanach of 2005 and earlier versions did not have SHA for it. Now, 2017 they do.  So, my question is, why Polaris wasn't included in the list of observable stars in Pub.249 and NAutical Almanacs and is it any way to guess it SHA without jeopardasing the accuracy of plotting too much?

I wanted to place the question as the new one but am not  not sure how to do it.  So I just place it in Sight Reduction forum.

Amelia Earhart and Fred Noonan disappeared into the Pacific ocean in 1937, 80 years ago, and there are still people trying to figure out what happened to them and why.

The story below, click on it, explains that a government chart they used listed Howland island 7 miles Northwest of its actual location. 

Amelia Earhart- inaccurate chart?

It has been often said, "you must be blind not to see an island 2 miles long from an airplane about 1,000 feet off the water".  Consider this- they were flying, upon approach, into the Sun and then turned to follow an LOP on what they thought was passing through Howland- 157° - 337°.  I assume they flew the line in both of those directions looking for Howland.

Now then, here's a picture of Howland- how well can you see it?  I can't see it very well and would assume its the shadow of a cloud cast on the ocean.  Combine those circumstances with the longevity of the length of the flight- they must've been very tired.





Paul

This is late but Jupiter and the Moon are within a few degrees of each other.

On April 10 at GMT 21 Jupiter was 2° South of the Moon.

Perhaps you saw it?

Regardless, the view now, April 11 at GMT 02:35 is quite impressive!

Clear skies,

CelNav57

Can I assume the procedure is the same as the bubble sextant when using an AH?

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I spent a nice sunny day today plotting some sights I took of Arcturus and Jupiter the other night and then a sun sight today. They all plotted exceptionally tightly for my bubble sextant.
 And since I had nothing better to do and hadn't shot the moon in some time, I dug out some old moon sights from a few years back and re-figured them.
 When I originally shot them, I was at a friend's place in the country and took a quick opportunity to 'get the moon' as I hadn't done that yet. I didn't quite know how to do the moon sight reduction then or the v correction so it was nice to go back and re-do them and brush up all at once. To complicate things more, I had an unknown amount of index error at the time and was trying different numbers to try and get an average. So today I plugged in what I know to be the correct IC and it was good to see all the LOPs move in the right direction and get 'tightish' on the location I had been at when I took the sights. 

Ahhh, fun times, lol.

hi,
why there's not v correction for the sun GHA?
In italy the "Nautical Almanac" have the v correction for the sun.
Maybe its not important but sometimes give me a correction of 0.2'/0.3' on the sun GHA

thank you!
Alberto

Here's a good site for graphical weather conditions.

WindyTV


It would make a great a screen saver too.

Paul

BillofTheNorth has made an informative video on how to use Concise Sight Reduction Tables found in the USNO's Nautical Almanac.

It is well presented, enjoyable and very understandable.

Find it here- Nautical Almanac Tutorial / Explanation - for the layperson


Thanks, Bill

CelNav57