# Sight reduction

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

Canonical page: [https://chrome-stats.com/d/com.Sightreduction](https://chrome-stats.com/d/com.Sightreduction)

## Overview

- **ID:** `com.Sightreduction`
- **Platform:** Android
- **Type:** Android app
- **Status:** Available
- **Publisher:** Navigational Algorithms
- **Category:** MAPS\_AND\_NAVIGATION
- **Downloads:** 32,451
- **Rating:** 3.67 / 5 (122 ratings)
- **Version:** 4.12
- **Last updated:** 2025-04-25
- **First published:** 2014-07-21
- **Publisher country:** ES
- **Size:** 10 MB
- **Data as of:** 2026-09-06
- **Store listing:** [Google Play Store](https://play.google.com/store/apps/details?id=com.Sightreduction)
- **Website:** [http://sites.google.com/site/navigationalalgorithms/](http://sites.google.com/site/navigationalalgorithms/)
- **Privacy policy:** [https://sites.google.com/site/navigationalalgorithms/software/android](https://sites.google.com/site/navigationalalgorithms/software/android)

## Description

**Sight Reduction** is a powerful Chrome extension designed for celestial navigation enthusiasts and professionals. It helps users perform sight reduction by calculating the intercept and azimuth using the Marcq Saint Hilaire intercept method, based on observed altitude and Nautical Almanac data.

Key features include input options for observed altitude, calculation of intercept (p=Ho-Hc) and azimuth (Zn), running fixes, and the ability to plot up to three Lines of Position on Google Maps. It provides tools for calculating Local Hour Angle (LHA), a list of navigational stars, and a logbook feature with output copied to clipboard.

Optimized with a user-friendly interface, the extension supports GPS location detection for GNSS fixes, multiple map types (standard, terrain, satellite), and zoom controls. Sight Reduction is essential for sailors and navigators seeking precise astronavigation solutions.

## Rankings

- #357,264 — Overall

## Permissions and access

### Permissions

- `android.permission.ACCESS_COARSE_LOCATION`
- `android.permission.ACCESS_FINE_LOCATION`
- `android.permission.ACCESS_NETWORK_STATE`
- `android.permission.FOREGROUND_SERVICE`
- `android.permission.INTERNET`
- `com.Sightreduction.DYNAMIC_RECEIVER_NOT_EXPORTED_PERMISSION`
- `com.google.android.providers.gsf.permission.READ_GSERVICES`

## Review summary

Users appreciate the app as a valuable navigation aid that saves time and works well especially with a nautical almanac app. However, multiple reviews mention issues such as absence of time input for sights, data loss when rotating the screen, and difficulties with data entry including negative instrument corrections. Improving the interface and adding time specification would enhance usability.

### Pros

- Great reference material for sight reduction and navigation calculations.
- Saves significant time and effort compared to manual paper methods.
- Works well when used in conjunction with a nautical almanac app.
- Helpful for quick plotting of fixes and verifying navigational work.
- Provides a reliable backup to GPS navigation.

### Cons

- Lacks time specification for each sight, limiting navigation accuracy.
- Data entry interface is cumbersome and could be improved.
- App loses previous Line of Position (LOP) data when device orientation changes.
- Difficulty entering negative instrument correction values, requiring workarounds.

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Source: [Chrome-Stats](https://chrome-stats.com/d/com.Sightreduction)