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Noonsite Almanac Generator

Using this tool you can generate a table of highly accurate astronomical data tailored to solving Latitude and Longitude based on the meridian passage (noonsite) of the sun.  In addition to these tables, you'll need the corrections to sextant altitude measurements.  For the navigation technique see How to Take a Noonsite.  On-Line Noonsite Almanac for Celestial Navigation is Based on Henning Umland's Java scripts for "LONG-TERM ALMANAC FOR SUN, MOON, BRIGHTER PLANETS, AND POLARIS  V1.12" Copyright � 2001–2004 Henning Umland.  Routines were added to search for noonsite solutions, but no other modifications were made to the script.  Any errors occurring with the Java Script are not a result of Henning Umland.  See disclaimers at the bottom of the page.

Enter the Start Date in the first 3 boxes.  You can leave the Time (UT1) blank.  Delta T needs to be entered based on the following table (however it won't impact your noonsite accuracy significantly):
YEAR      DELTA T

2011.0:  +66.70
2012.0:  +67.30
2013.0:  +67.50
2014.0:  +67.80
2015.0:  +68.00

See this site for tables of Delta T spanning the decades. Or the US Navy site for tables of Delta T in the short term.

y m d h m s s
 Date:        Time (UT1):         Delta T:             
          (time can be left blank) days      
         

Number of days to run Almanac:

 
 

Note: if you run this longer than 7 days you will get multiple "Unresponsive Script Warnings". This program takes a long time to complete so just keep hitting continue.


Original Program Description As it pertains to Noonsite Calculations:
The script for creating noonsite solutions was based on Hemming Umland's work. 

This computer almanac is based upon the VSOP87D Theory, the 1980 IAU Nutation Theory, the ELP2000 Theory (truncated) and formulas published in Astronomical Algorithms by Jean Meeus. The program calculates Greenwich hour angle (GHA), right ascension (RA), and declination (Dec) for Sun, Moon, Venus, Mars, Jupiter, Saturn, and Polaris (apparent positions).  (Calculations for bodies other than the Sun have been removed for the Noonsite Application).

GHA and RA refer to the true equinox of date.

The almanac can be used for many decades, provided the Delta T value (= TT–UT1) for the given date is known. An accuracy of approx. ±1s is sufficient for most applications. Errors in Delta T have a much greater influence on the coordinates of the moon than on the other results. Delta T is obtained through the following formula:

Delta T = 32.184s + (TAI – UTC) – (UT1-UTC)

Current values for TAI–UTC and UT1–UTC are published on the web site of the IERS Rapid Service / Prediction Center (IERS Bulletin A).

Accuracy (approximate values):

GHA and Dec of Sun and planets: ±1"
RA of Sun and planets: ±0.1s
SD: ±0.1"
Nutation (d psi and d epsilon): ±0.001"
Mean Obliquity of the Ecliptic: ±0.001"
Lunar distance of Sun: ±10"

This program is freeware and may be copied and distributed in unmodified form and on a non-profit basis. For your private use, feel free to modify the source code according to your requirements. Any commercial distribution requires the author's permission.

Henning Umland       N 53° 20' 34''   E 9° 52' 00''

Check this web site for updated versions of celestial scripts: http://www.celnav.de/index.htm
The noonsite search routines on this page were written by Eric Baicy.


Warranty disclaimer:
Results obtained with this program have been cross-checked with Interactive Computer Ephemeris 0.51 by USNO. However, the program is still experimental and may contain errors leading to unexpected results in rare cases. Use at your own risk.

Warning:
Editing and modifying the JavaScript code may lead to unpredictable results. Users who are not familiar with JavaScript and calculations of ephemerides are strongly advised to leave the code unchanged.