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.