AP 3270 Vol 1, Astro / Epoch question?

[Skylark]

A question, if I may, addressed to those skilled in the art of Celestial navigation.

My copy of AP 3270 Vol 1 is Epoch 2010.0 and the forward says that "it is intended for use for about 5 years"

GHA of Aries is shown within Tables from 2006-2014, for example.

Is it now of any use in preparing for a twilight selected start sight / fix or is it consigned to the library and must be replaced by the Epoch 2015.0 version?

Many thanks for your wisdom!

 

[Neil]

Yes, I checked mine and looked to http://msi.nga.mil, where I originally downloaded all three volumes. I now find Vol 1 missing, but note that the US site says the the UKHO retains copyright over Vol 1. It costs £30.

I find it irritating that the US publishes its data for free, on the basis that the data was payed for by US tax paying citizens, but that the UKHO charges for data payed for by the tax payer. I imagine our US cousins are equally cheesed off when they go to their site and can only find Vols 2 & 3

It doesn't say whether or not it is Epoch 2020

 

[Latitude52°N]

On the site of Celestaire (https://www.celestaire.com/pubs/category/3-pub-249.html) you can find Pub 249 Vol1 2015 selected stars in PDF format. On a spot check between the 2010 version and the 2015 version I found 3-4' difference, leading to 3-4 nm difference in Intercept.

 

[Skylark]

Many thanks for posting the link to an Epoch 2015 version! Very helpful (and welcome to the forum, too)

I've printed a couple of pages at random and I'll check the differences against my 2010 version later. If I find similar values to you, I'll happily keep and use my Tables for another 5 years (at least).

 

[Latitude52°N]

Thank you,
in Selected stars is a table for precession and nutation (Table 5) for other years then 2010 (or 2015). Entering with Latitude and LHA Aries it gives the difference in distance and bearing. Four years from the reference year and close to the equator the difference is greatest. Sadly the table doesn't cover more then 4 years form the reference year.