Navigation Sight Reduction Calculators

The following links are interactive calculators for reducing sights. Once you have clicked on the link, you can do "save as" in your browser to save the page. This allows you to use the calculators while you are disconnected from the web by accessing the saved page with your browser. This works because these pages are written in JavaScript which runs locally in your own browser and does not depend on a server.

• Given a point, find a new point a given distance and direction away
• Given two points, find the distance and direction from the first to the second (same page as above)
• Calculates Hc, Zn LHA, Lat, Dec from degrees and minutes (Original Version - has parameter entry in different order from SR96)
• Calculates Hc, Zn LHA, Lat, Dec from degrees and minutes (Easier to use ) 11-1-2008
• Calculates complete SR 96s sight reduction form except for main and increments almanac entries
• Given DRs and EPs from two sights, find the position of the fix where the LOPs intersect

Prior versions

• Calculates Hc, Zn from LHA, Lat, Dec in decimal degrees (Version 0)
• Calculates Hc, Zn LHA, Lat, Dec from degrees and minutes (Version 1)
• Calculates Hc, Zn LHA, Lat, Dec from degrees and minutes (Version 2)
• Calculates Hc, Zn LHA, Lat, Dec from degrees and minutes (Version 3)

Navigation Manual Sight Reductions Using The ABHAV method

Here is a paper on a simplified Sight Reduction Method and an online sight reduction calculator that can be used to check answers.

• Here is a paper on the ABHAV sight reduction method.

  Here are the figures including the example and blank forms referenced in the text.

  Figure 1 (postscript)
  Figure 2 (text)
  Figure 3 (text)
  Figure 4 (text)
  Figure 5 (text)
  Tables for 36-47 degrees(text)

  Here you can find the complete set of tables from 0 to 179 degrees in html format that you can print out and carry with you.

  The complete set of tables

  The following program can be used to generate either the text or html tables on the web site. It can be compiled with

  cc abhav.c -lm -o abhav

  To generate html tables, give

  abhav -h table -s 0 -e 179

  and it will generate tables in files named table00.html to table59.html containing the tables starting from 0 degrees and ending at 179 degrees. Without the -h option, the output will be in text format and placed on the standard output. With netscape, the right mouse menu "save as" can be used to save a copy of the file. You will need to rename it to abhav.c before compiling.

  Table generation software

  This method is a simple yet accurate and with a copy of the modest length tables, can be easily performed without electronic equipment.

  You can even try the online javascript sight reduction program above to check your answers.

---

Disclaimer: Always use multiple methods to check your results when navigating. While these tables and formula are believed to be correct, every entry has not been checked against a second computational method.

Comments can be mailed to the Webmaster at: webmaster@snark.dhs.org

---

This is a javascript test link called jstest. It will likely give meaningless or wrong output. Don't use.
This is a javascript test link called jstest1. It may give meaningless or wrong output, but is the latest and greatest.