1. Our Current Astro-Navigation Solutions Catherine Hohenkerk HM Nautical Almanac Office UK Hydrographic Office

2. Astro-Navigation Sextant, UT1 & the means of “Sight Reduction”  Almanac  The Nautical Almanac  Sight Reduction Tables (SRT)  NA’s Concise SRT  Marine Navigation : 6 Volumes  Rapid SRT Navigation: 3 Volumes–AP3270  Software (or a calculator)  NavPac

3. The Nautical Almanac (NA) First published in 1767

4. Extract: NA right-hand page

5. Extract: NA left-hand page 1960, joint pub. with US Naval Observatory

6. The Nautical Almanac (NP314) First published in 1767 Current layout developed in the 50s 1960, joint pub. with US Naval Observatory Licensed world wide, via HOs & commercial companies An almanac + algorithm for reduction of sights + Concise Sight Reduction Tables An NA is a SOLAS requirement

7. NA Concise Reduction Tables  Altitude (Hc) to 1' and Azimuth (Zn) 1 °  Developed in the US (USNO)

8. NA Concise Reduction Tables  Developed in the US (USNO)  Altitude (Hc) and Azimuth (Zn)  For use in an emergency  Compact — only 32 pages of tables  Method accurate to ~2'  Complicated to use?

9. Sight Reduction Tables for  Marine Navigation, NP 401, 6 Volumes  Altitude (Hc) to 0'.1 and Azimuth (Zn) to 0º.1  Used with an almanac & compatible with NA  Accuracy of method 0'.2 - 0'.3  Joint publication, HMNAO/UKHO, USNO/NGA  UKHO have ceased printing this volume  US edition (Pub 229) is still available

10. Rapid Sight Reduction Tables for Navigation  Air Navigation, AP 3270 / NP 303  3 Volumes  Altitude (Hc) to 1' & Azimuth (Zn)

11. AP3270 / NP 303 : Volume 1 Selected Stars, 2015  Method accurate to 0'.5

12. AP3270 / NP 303, Volume 2 & 3

13. Rapid Sight Reduction Tables for Navigation  Air Navigation, AP 3270 / NP 303, 3 Vols  Altitude (Hc) & Azimuth (Zn)  Volume 1, Selected Stars, “7 best”  Volume 2 & 3, require an almanac  Joint publication of HMNAO, USNO (429)  2015 edition of Volume 1, published June

14. NavPac Software : 1986 - 2015 Digital / PC Ephemerides Position 0'.15 NA + AP3270 + GC/Rhumb sailing + Az for compass checks Calculations RN Recommended

15. NavPac—RiseSet Times of: Rise & Set Twilights Meridian Passage and Altitude at Mer.pass

16. NavPac—RiseSet Compass Check Times when Calculated altitude = 0 ° Azimuth

17. NavPac—Findit

18. An Astronomical Observation NavPac Sights

19. NavPac—Sights Results Calculations

20. NavPac—Almanac

21. NavPac—Finder Rhumb Line/Great Circle Routes

22. Astro-Navigation for the Future  Web availability?  Software platform independence?  Adobe Acrobat (pdf) e-NA, e-AP3270?  Polar navigation?  UT1/UTC issues?  What do you think?