The real books · Page 2 of 5
A page of Pub. 249 Vols. 2 and 3
Every page has the same parts. Tap each one to see where it is and what it is for. The numbers are real: they are the same values the printed book gives for latitude 32°, declinations 13° and 14° of the same name (the book has fifteen declination columns across each page).
7N. Lat.: LHA over 180°, Zn = Z; LHA under 180°, Zn = 360° − Z. S. Lat.: LHA over 180°, Zn = 180° − Z; LHA under 180°, Zn = 180° + Z.
1. Latitude. Each section of the book is for one whole degree of latitude, printed in the corner of every page. You always enter with your AP latitude, never the declination.
How the book is laid out
- By latitude, one whole degree after another. Within each latitude come the pages for declination 0°–14°, then the pages for 15°–29°.
- Same name first, then contrary. Within each group the same-name tables come first, running down the page. After a break come the contrary-name tables, printed the other way round: the LHA runs upward from the bottom of the section. Read them from the foot of the section and they look just like the same-name ones.
- LHA 0°–180° is always on the left, 180°–360° on the right, whichever name you are in.
- Above latitude 69° the LHA goes in steps of 2°, so choose the AP longitude to make LHA an even degree.
- Table 5 is at the back of the book (and on the loose bookmark that comes with it): enter it with d and the minutes of declination.
- Hc can be negative near the horizon: the tables carry on below 0°. Apply Table 5 with care there, minding the signs.
The course’s Pub. 249 panel is a page of the book with fewer columns, so that it fits a phone. It shows the chosen declination and the next one, which is enough to see which way d goes. Practice on it in The intercept method: Reading Pub. 249.