## How do you calculate hour angle?

The hour angle is the angular displacement of the sun east or west of the local meridian due to rotation of the earth on its axis at 15° per hour with morning being negative and afternoon being positive. For example, at 10:30 a.m. local apparent time the hour angle is −22.5° (15° per hour times 1.5 hours before noon).

## How are latitudes calculated?

Your latitude can be calculated by measuring the angle of the sun. At the middle of the day on the equinox (when day and night are the same length) the angle of the sun below an upright line (a line straight up above your head) tells you your latitude.

**How do you count the meridians?**

The meridians from West of Greenwich (0°) to the antimeridian (180°) define the Western Hemisphere and the meridians from East of Greenwich (0°) to the antimeridian (180°) define the Eastern Hemisphere. Most maps show the lines of longitude.

**How do you calculate long Chron?**

After meridian passage, LHA will be between 000 and 180.So, to calculate LHA, If it given that the sight is taken AM at ship or meridian of east, then P = LHA. If it is given that the sight is taken at PM at ship, then P = 360 – LHA.

### How is sextant altitude calculated?

Dip = 1.77 h², where h= height of observer above sea level in meters. The navigator on the ship’s bridge when observing any celestial body brings the body down to the line of sea horizon and measures the angle of one of its limb. This angle measured is called as the Sextant altitude of the body.

### How do you calculate solar hours?

From ɣ, we calculate the equation of time. From the offset, the corrected LST is LST + Offset = 15.5 + 20.36/60 = 15.84 hours. The solar hour angle for a given data is h = 15 × (15.84 − 12) = 57.6°. The corrected angle differs by 57.6° − 52.5° = 5.1°.

**How is solar time calculated?**

To determine Lst, multiply the difference in time between local standard clock time and Greenwich Mean Time (GMT) by 15°. This relationship comes from the fact that the sun takes 4 minutes to traverse 1° of longitude. Thus, if your local standard clock is 1 hour behind GMT then LST is 15°.

**What are the 3 types of latitude?**

Technically, there are different kinds of latitude—geocentric, astronomical, and geographic (or geodetic)—but there are only minor differences between them. In most common references, geocentric latitude is implied.

## How to calculate the time of meridian passage?

The long method involves calculating the time of meridian passage at the present position an hour or so before noon and then plotting a new DR position for that time. In this way, the time of meridian passage at the new DR position can then be calculated in advance. Note.

## What is the short Meridian Passage method?

The short method involves calculating the time of local meridian passage at the vessel’s present geographical position shortly before noon and then measuring the Sun’s altitude as that time approaches. Outline of the Six-Step Proforma for the Meridian Passage Short Method.

**How to use a sextant to measure the sun’s altitude?**

1- About 20 minutes before the expected meridian passage time, take a Sun sight with the sextant. Record the time and altitude. 2- At the expected meridian passage time, the Sun will reach the higher altitude for the day, and will appear to hang with constant altitude for a while.

**How to calculate latitude from the Sun?**

We also learned that if we measure the Sun’s altitude at local meridian passage and use the result together with the Sun’s declination, we can calculate our latitude. The short method is used for stationary or very slow moving vessels and involves calculating the time of meridian passage at the current DR position.