Sight reduction

Sight reduction

Celestial navigation. Take the sextant and get your Line of Position.

App info


4.12
April 25, 2025
31,113
Android 4.0+
Everyone
Get Sight reduction for Free on Google Play

App description


Android App Analysis and Review: Sight reduction, Developed by Navigational Algorithms. Listed in Maps & navigation Category. Current Version Is 4.12, Updated On 25/04/2025 . According to users reviews on Google Play: Sight reduction. Achieved Over 31 thousand Installs. Sight reduction Currently Has 125 Reviews, Average Rating 4.3 Stars

Celestial navigation - Astronavigation

Sight reduction:
- Marcq Saint Hilaire Line of Position, intercept method (p=Ho-Hc, Zn)
- Input for observed altitude Ho or instrumental Hs (Nautical Almanac data needed for the Sun and the Moon)
- Calculator for Intercept method (p=Ho-Hc, Zn) altitude Hc and azimuth Zn
- Running fix
- Plots up to 3 Marcq Saint Hilaire Lines of Position on Google maps
- Local hour angle (LHA)
- List of navigational stars
- Logbook (output is copied to clipboard)
- New optimized user interface
- GNSS fix to check the solution

Sight reduction is the process of deriving from a sight the information needed for establishing a line of position.
This app is a calculator to get the intercept from the assumed position of the observer AP(latitude, longitude), the geographical position of the celestial body observed, GP(Dec, GHA), and its corrected altitude Ho.
Manual and examples in the developer's website.

Ref: https://en.wikipedia.org/wiki/Sight_reduction

User interface:
- Zoom buttons +/-
- Map types: standard, terrain, and satellite
- GPS location. ("Location" App permission must be allowed. Switch on you GPS, and then automatic location detection is possible)
We are currently offering version 4.12. This is our latest, most optimized version. It is suitable for many different devices. Free download directly apk from the Google Play Store or other versions we're hosting. Moreover, you can download without registration and no login required.

We have more than 2000+ available devices for Samsung, Xiaomi, Huawei, Oppo, Vivo, Motorola, LG, Google, OnePlus, Sony, Tablet ... with so many options, it’s easy for you to choose games or software that fit your device.

It can come in handy if there are any country restrictions or any restrictions from the side of your device on the Google App Store.

What's New


Upgraded to:
Android 16 - SDK 36
new Google Maps 'com.google.android.gms:play-services-maps:19.2.0'

Rate and review on Google Play store


4.3
125 total
5 70.7
4 4.9
3 14.6
2 0
1 9.8

Total number of installs (*estimated)

Estimation of total number of installs on Google Play, Approximated from number of ratings and install bounds achieved on Google Play.

Recent Comments

user
joel buttle

This app is useless for navigation because you can't specify the time at each sight. Would be very handy if there was a time perameter in the LOP box.

user
Martin Leininger

Does not appear to have instructions or nautical almanac.

user
A Google user

Works fine now

user
A Google user

Great app, but I have two points to mention. 1) When I twist the smartphone (Samsung S-7) to horizontal all the previous LOPs disappear. So I have to re-enter all that data. Argh! 2) It's seemingly impossible to enter a negative IC (instrument correction). The work-around I use is to enter a negative value in some other APP and then copy/paste into the IC correction space. In conjunction with the Nautical Almanac app that I have this is a near perfect combination. I'm not giving up my GPS units, but it sure is nice to have some old-school stuff around as a back-up.

user
A Google user

fix it please..

user
A Google user

Very Helpful! Thanks

user
A Google user

Ideal for saving time plotting a fix or simply checking your work. Recommend using the developer's almanac app alongside this one. Thanks!

user
A Google user

Can be used to yuor good correction..wow