Astro tables

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Neil

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I'm working through Tom Cunliffe's book (for the nth time!) and I feel ready to start practicing with the real thing (even though it's only for the sake of the mental exercise). However, finding a nautical almanac and the sight reduction tables NP303(1,2,&3) seems to be a sticking point - Amazon is out of stock and they are not sold at most corner magazine kiosks - where should one go for a good price (and availability)?

Are there any alternatives that I should consider?

Also, is there available, a list of mathematical operations that will reduce a sight without tables? I know that there are programmable calculators that do it. However, I'm getting ahead of myself and my limited abilities here.........
 
Are there any alternatives that I should consider?
Click to expand...

Yes.

Lt Cdr Harry Baker's Astro Navigation Tables, by Adlard Coles Nautical. Last time I looked, this slim volume that has just about everything you need cost just £16.99.

I've used it on blue water. I got there and back again, just fine.

As for the Sainted Cunliffe, he quotes on the rear "Nothing I have seen comes near to the sensible format which I see before me".

You'll find also some detail inside pointing to a programming process for a programmable calculator, which works, and also a source for a suitable calculator already programmed.

Enjoi!

:)
 
Thanks for the replies, and the pdf's of the sight reduction tables are handy. I'll check out the others; my only concern is the format of the tables - Cunliffe bases his workings on the full tables - as a beginner, will I be able to extract the correct data from these apparently condensed works?
 
The US Tables (Pub.249) are the same as the UKs Rapid Sight Reduction Tables (now published the UKHO, and used to be known as Air Tables AP3270).
The US tables are reprinted by Celestair and are available in the UK from www.seachest.co.uk among other, as is the Nautical Almanac reprinted by Celestair as the Commercial Nautical Almanac.
The US tables are cheaper and slightly smaller format than the UK versions.
 
Neil

Sight reduction tables (as available today) are a joint invention by the UK and the US.

They come in two printed formats :

Marine tables, with an accuracy of 0.1 of a minute of arc and in 6 vols. ( NP 401 UK and US PUB 229) – large heavy expensive hardbacks that last forever.

Air tables, with an accuracy of 1.0 min. of arc and in 3 vols. ( NP 3270 UK and US PUB 249)
The accuracy is sufficient for us yachties and so these are the ones that are generally used at sea. They are more limited in application than the original marine tables but no matter.
Volume 1 has to be replaced every 10 years or so.

The UK Admiralty publications are expensive - the US a lot cheaper and they are available free on line. They are also published in the US by Celestaire as a ’commercial’ edition which is paper back, smaller and cheaper that the official version.
If you can buy, second hand, US 249 vols 2 & 3 in the Celestaire format then this is the cheapest way – avoid old copies of Vol. 1 , it will be out of date and useless.

The US publishes all the tables and almanac free on line, however there was a problem last year with errors in the on line version but I think this might have been resolved – I don’t know .. does anyone else ?

You will also need this year’s ‘Nautical Almanac’ – the above pricing details also apply, the cheapest edition is the ‘commercial’ Celestaire one.

Most of the condensed books use their own formulae and do not relate to the above tables, Cunliffe and the RYA courses use the Air tables.

All the above tables and Almanac are identical, whether UK or US.

Good luck – and see the thread on ‘ the first thousand sights being the least accurate’ or words to that effect !

As to the where, try Piplers or Adlard Coles, for 2nd hand try Abebooks - I have used them often and successfully bought books from the US at a cheaper price inc. postage.
 
Neil said:
Thanks for the replies, and the pdf's of the sight reduction tables are handy. I'll check out the others; my only concern is the format of the tables - Cunliffe bases his workings on the full tables - as a beginner, will I be able to extract the correct data from these apparently condensed works?
Click to expand...

Shouldn't be a problem, although obviously you won't be able to just follow the Cunliffe method step by step.

Don't know about Lady C's recommendation, but The Complete On-Board Celestial Navigator has worked examples and a simple long term almanac, which is good until the end of 2011. The actual sight reduction tables therein are useful without limit of time and could easily be detached for use with another almanac in the future.

The whole publication costs less than half the price of the annual official Nautical Almanac. The current Amazon price for TCOBCN probably reflects the fact that the long term almanac is approaching its use by date next year.
 
Neil said:
Thanks for the replies, and the pdf's of the sight reduction tables are handy. I'll check out the others; my only concern is the format of the tables - Cunliffe bases his workings on the full tables - as a beginner, will I be able to extract the correct data from these apparently condensed works?
Click to expand...
The tables on the US Gov't website are "the full tables" (not condensed, unless you print them to fit on smaller paper than they are intended for!) and include both the air and marine versions. FWIW, I would be surprised if Tom refers to the marine tables: most people regard them as way OTT for yottigation.
 
Any Admiralty International Chart Agent will carry the full sets of Tables and the Almanac(s).

I will stick my paw up as an NP401 user, because I learned from "Little Ship Astro-Navigation" which uses them. In practice you don't need all six volumes - I get along fine with two - latitudes 45-60 and 60-75. They are nice and easy to use.

You can sometime snaffle volumes 2 and 3 of NP3230 on Ebay; don't make the mistake of buying Volume One ("Selected Star")!
 
timbartlett said:
The tables on the US Gov't website are "the full tables" (not condensed, unless you print them to fit on smaller paper than they are intended for!) and include both the air and marine versions. FWIW, I would be surprised if Tom refers to the marine tables: most people regard them as way OTT for yottigation.
Click to expand...

Yes, you're right Cunliffe uses the air tables - my question related to the other publications that were much more condensed that the air tables. I'll try the combined one that go up to 2011 - It's only 13 quid.....

I'll probably download the air tables, since the're free - but do they also do an astro almanac? couldn't see one.
 
Minn said:
don't make the mistake of buying Volume One ("Selected Star")!
Click to expand...
Actually, Seven selected Stars is a brilliant publication that takes all the aggro out of planning and reducing star sights, to such an extent that they are actually easier than sun sights (so long as you can get the little buggers to stay in the sextant field of view while you shoot them!)
So it's not "a mistake" per se ... it's only a mistake if you think you're going to be able to use it for sun sights!
 
What an incredibly useful thread!

I've invested approx £100 in AP3270 Vol 1,2 & 3 and the American version of the Nautical Almanc. No regrets.

However, there is a fair weight associated with these publications and a huge advantage of the downloads is that you can print the days of your intended passage and the appropriate latitudes for sight reduction.

A big saving in weight, particularly for one-way trips.

Many thanks :)
 
David

Later this year the Admiralty are printing all 3 vols of 3270 in an 'A4' format, or so they say.
A good few pounds lighter I think.

Neil

Ask Brendan of this parish how to print the unprintable - if anyone knows it will be him - perhaps a PM ? Or Google 'unlock pdfs'

For increments ( inc. and corr. as is known ) and moon stuff - if you PM me with your address I will send you an old almanac - it's all in there.

Stephen
 
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The Complete On-Board Celestial Navigator

For those who like to know the maths behind these sight reduction tables, here is the author's response to an enquiry I made some time ago:

"You will find a detailed explanation of the book at
http://gbennett.customer.netspace.net.au/ etc. (interesting links and downloads here)

However the mathematical basis of the tables is as follows:

LHA & SUM : J Log sinx/2
LAT & DEC : J/2 log cos x
L ~ D & RES : K(1-cosx)
where J = -26059.70314 and K = 99999.

All logarithms are to the base 10 and
all results are rounded off to the nearest integer.

The formulae using these functions is given in Bowditch,
The American Practical Navigator as follows,
hav theta = cos Lat cos Dec hav LHA
hav (zenith distance) = hav (Lat~ Dec) + hav theta

George Bennett."

The tables are thus a modified and compact form of the standard cosine-haversine formula, which is also the basis of AP 3270 and most inspection tables. For the user, no knowledge of logarithms or spherical trig is required, just simple addition.
 
timbartlett said:
Actually, Seven selected Stars is a brilliant publication that takes all the aggro out of planning and reducing star sights, to such an extent that they are actually easier than sun sights (so long as you can get the little buggers to stay in the sextant field of view while you shoot them!)
So it's not "a mistake" per se ... it's only a mistake if you think you're going to be able to use it for sun sights!
Click to expand...

Tim, we are at cross purposes - I meant "don't buy an old epoch copy on ebay"!

I agree it's an excellent publication (if current!)
 
stephenh said:
David

Later this year the Admiralty are printing all 3 vols of 3270 in an 'A4' format, or so they say.
A good few pounds lighter I think.

Neil

Ask Brendan of this parish how to print the unprintable - if anyone knows it will be him - perhaps a PM ? Or Google 'unlock pdfs'

For increments ( inc. and corr. as is known ) and moon stuff - if you PM me with your address I will send you an old almanac - it's all in there.

Stephen
Click to expand...

Got that unlocked online - cheers! Now I'm good to go, just need knowledge, practice and experience.
 
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