Calculation: sextant altitude Hs to apparent altitude Ha to correct the sextant’s inherent errors and the error induced by the height of the eye (Dip) above the horizon. (Altitude = Height)
![the sextant 3/4 from behind](https://easysextant.com/wp-content/uploads/2024/06/sextant-34-arriere.jpg)
This page contributes to the primary objective of offering guidance and interactivity on the calculation and understanding of the Line of Position (LOP) using only a sextant and the sun, and then tracing this line on a plotting sheet. See recommendations.
![sextant altitude to apparent altitude, sextant inherent errors and due to height of the eye above the sea level](https://easysextant.com/wp-content/uploads/2023/12/la-rochelle-Hs-to-Ha-728x1024.webp)
![](https://easysextant.com/wp-content/uploads/2023/07/800px-Gfp-Rain-on-lake-michigan-at-newport-state-park-wisconsin-copie.jpg)
On this page, we will learn how to calculate the apparent height of the sun. However, I recommend first reading the theory of apparent sextant height.
sextant altitude to apparent altitude: On this page
Calculating Hs to Ha:
![sextant altitude to apparent altitude, sextant inherent errors and due to height of the eye above the sea level](https://easysextant.com/wp-content/uploads/2023/12/Hs-to-Ha-791x1024.webp)
![Corrections from sextant altitude to apparent altitude using images.](https://easysextant.com/wp-content/uploads/2024/09/sextant-altitude-to-apparent-altitude.jpg)
![](https://easysextant.com/wp-content/uploads/2023/12/inexerror-plus-non-adjust.erroe_-1024x372.webp)
(The Dip error is always negative !)
![](https://easysextant.com/wp-content/uploads/2023/07/800px-Rainy_Beach_2-jpeg.webp)
sextant altitude to apparent altitude: example
![Corrections from sextant altitude to apparent altitude using images.](https://easysextant.com/wp-content/uploads/2024/09/sextant-altitude-to-apparent-altitude.jpg)
How to calculate apparent height (Ha)
The entries:
sextant altitude
![sextant altitude to apparent altitude lecture sextant altitude image](https://easysextant.com/wp-content/uploads/2022/08/lecture-sext-74°6-copie-998x1024.jpg)
Hs = 74° 06′
Index error
![sextant altitude to apparent altitude: image sextant index error](https://easysextant.com/wp-content/uploads/2022/06/parralax-2.jpg)
Index error = + 0° 07′
Non adjustable error
![sextant altitude to apparent altitude image inspection certificate](https://easysextant.com/wp-content/uploads/2022/09/certivicat-revised-1.jpg)
Hs = 74°06 is about 75° so the error is +1′
Non adjustable error = + 0° 01′
ε = non-adjustable error + index error = + 8′
![](https://easysextant.com/wp-content/uploads/2023/12/inexerror-plus-non-adjust.erroe_-1024x372.webp)
eye height (Dip error)
![sextant altitude to apparent altitude image eye height](https://easysextant.com/wp-content/uploads/2022/09/hauteur-loeil-2-m.jpg)
DIP = – 0°02′,5 = – 2′,5 (eye height = 2 meters)
DIP of the horizon: see altitude correction table
ALTITUDE CORRECTION TABLE:
![](https://easysextant.com/wp-content/uploads/2024/06/altitude-correction-table-sun1.jpg)
sextant altitude to apparent altitude: solution of the example
sextant height (Hs) to apparent height (Ha)
![](https://easysextant.com/wp-content/uploads/2023/11/Ha-anglais-jpg.webp)
Hs …………………..= 74° 06′, 0
ε ………………….. = + 00° 08′, 0
Dip………………… = – 00° 02′, 5
_________________________ +
Ha…………………. = 74° 11′, 5
sun correct LL ….= _ _° _ _’, _
__________________________ +
Ho…………………….= _ _° _ _’, _
![](https://easysextant.com/wp-content/uploads/2023/06/Flock_of_birds_over_the_Boukana_beach-jpeg.webp)