Our Current Astro-Navigation Solutions

1
Our CurrentAstro-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)
• NAs Concise SRT
• Marine Navigation 6 Volumes
• Rapid SRT Navigation 3 VolumesAP3270
• 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

• Developed in the US (USNO)

• Altitude (Hc) to 1' and Azimuth (Zn) 1

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
NavPacRiseSet

• Times of
• Rise Set
• Twilights
• Meridian Passage
• and
• Altitude at Mer.pass

16
NavPacRiseSet Compass Check

• Times when
• Calculated altitude 0
• Azimuth

17
NavPacFindit
18
An Astronomical Observation
NavPac Sights
19
NavPacSights Results

• Calculations

20
NavPacAlmanac
21
NavPacFinderRhumb 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?