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Support for the Traditional Navigator The Nautical Almanac
Catherine Hohenkerk
HM Nautical Almanac Office
The Nautical Almanac
and
Astronomical Ephemeris
for the Year 1767
Revd. Nevil Maskelyne, 5th Astronomer Royal (1765-
1811)
1763: Published his British Mariner's Guide, … suggests to facilitate … Lunar Distances should be calculated beforehand, for each year, and published in a form accessible to navigators.
1765: Appointed AR & on the Board of Longitude
By John Russell
© National Maritime Museum, London
All the Articles of the Ephemeris were computed by Two separate Persons, and examined by a Third, except Of the Moon's Longitude, Latitude, Right Ascension Declination, Semidiameter, and parallax, which, for Noon, were computed by One Person, and for Midnight by another, and the Truth of these Calculations ascertained by means of Differences, which, for the Moon's Longitude, were carried out as far as the Fourth Order.
Quality Control
NA 1767 published 1766
Computers
&
Comparers
:
Example of
Lunar
Distances
1785
1828: Nautical Almanac Act
Almanac fell into disrepute. It became notorious for its errors; February 29 was forgotten in the table of apparent places of stars in a particular leap year.
In 1818 it was said in the House of Commons that it had become "a bye-word amongst the literati of Europe”. The "leaves-on-the-track”; “Wrong kind of snow”!
Another story: A Spanish commander who, as a token of international courtesy, exchanged his own almanac for that of a British warship commander's; the Spaniard was never heard of again!
1831/1832 The Nautical Almanac Office
HMNAO at UKHO ----- Today, Tomorrow, …
UK National Hydrographer Division
Captain Jamie McMichael-Phillips
Dr Steven Bell (20 years)
Dr Donald Taylor (> 30 years)
Miss Catherine Hohenkerk (> 30 years)
Dr Julia Weratschnig (maternity leave till 2013 Spring)
Mr James Whittaker (2012)
Dr Susan Nelmes (starting at the end of October)
Dr Paresh Prema (starting at the end of October)
The Nautical Almanac and Astronomical Ephemeris
1896-1913 Part 1 NA & AE Published for Seamen
1914 ….
1896-1930 Part 2 NA & AE
1931-1959 NA & AE
1960-1980 Astronomical Ephemeris
1981 … The Astronomical Almanac
NA & AE 1767-1895
The Nautical Almanac 1914 - …
Abridged for the Use of Seamen
1914-1923 changes every year
1924-1928 remodeled for sailors
1929-1951 redesigned for navigators
The Abridged Nautical Almanac
1952 – 1958*, 1959*
The Nautical Almanac (NP314)
1960 - …
Various Titles
Astro-Navigation Today
Sextant, UT1 & the means of ―Sight Reduction‖
Almanac
The Nautical Almanac (NA)
Sight Reduction Tables (SRT)
NA’s Concise SRT
Marine Navigation : 6 Volumes
Rapid SRT Navigation: 3 Volumes–AP3270
Software (or a calculator)
NavPac
Extract: NA left-hand page
Extract: NA right-hand page
The Nautical Almanac (NP 314)
Joint publication with US Naval Observatory
Available world wide via UKHO
Licensed via
Hydrographic Offices
Commercial companies
An NA is a SOLAS requirement
2014
Sight Reduction Tables
NA Concise Reduction Tables (USNO)
NA Concise Reduction Tables (USNO)
For use in an emergency
Method accurate to ~2'
Compact — only 32 pages of tables
Complicated to use.
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
Rapid Sight Reduction Tables for Navigation
AP 3270 / NP 303
[Sight Reduction Tables for Air Navigation]
3 Volumes Altitude (Hc) to 1' & Azimuth (Zn)
Rapid Sight Reduction Tables for Navigation
AP3270 / NP 303 : Volume 1 Selected Stars, 2015
AP3270 / NP 303, Volumes 2 & 3
Rapid Sight Reduction Tables
AP 3270 / NP 303
Altitude (Hc) to 1' & Azimuth (Zn)
Vol 1, Selected Stars, 7 best
Vol 2 & 3, require an almanac
Method accurate to ~0'.5
Joint publication of HMNAO &
USNO
2015.0
NavPac Software : 1986 - 2015
Digital / PC
Ephemerides
Position 0'.15
NA + AP3270 +
GC/Rhumb sailing +
Az for compass checks
Does the Calculations!
RN Recommended
NavPac—RiseSet
Times of:
• Rise & Set
• Twilights
• Meridian Passage
and
• Altitude at Mer.pass
NavPac—RiseSet Compass Check
Times when
• Calculated
altitude =
0°
• Azimuth
NavPac—Findit
An Astronomical Observation
NavPac
Sights
NavPac—Sights Results Calculations
NavPac—Almanac
NavPac—Finder
Rhumb Line/Great Circle Routes
Astro-Navigation Issues for the Future
Modern NavPac improved interface, more functions
Platform independent?
Web availability?
Adobe Acrobat (pdf) e-NA, e-AP3270?
Polar navigation?
UT1/UTC and the possible dropping of leap seconds?
The Nautical Almanac
Support for the Navigator
You can’t jam it.
It doesn’t crash!
Thank you.