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​Moon's Calc
How to Calculate the Moon's Hour Angle and Declination
Find the hour angle and declination of January 1, 1:20 in U.T.C.
1. Find the nearest E☾ in the Nautical Almanac and confirm that the E☾ is before the observation time.
For example: If you want to find E☾ at 1:20, 1:30 is close, but look at 1:00.
2. E☾ is displayed in 30 minute increments, so if you want to know E☾ for any given time period, you can use the P.P. table in the right column to find the correction value, because unlike E☾, E☾ is highly variable.
3. The hour angle can be easily obtained by adding the observation time (U.T.C.) to E* obtained in step 2.
4. Since the hour angle obtained is in units of time, it can be multiplied by 15 to obtain the angle in units of angle.
5. In the case of declination, it is obtained in the same way as above.
Find the midday time of the moon at 28°N, 165°E on January 2.
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How to calculate the Moon's midday time.
1. in the case of the Moon, since it moves faster than other celestial bodies, it is necessary to refer to the previous day's value for the eastern longitude and the next day's value for the western longitude.
2. Find the lunar mean times of the two days in the sample image and the day before. (Time in blue box)
3. find the difference between these two mean times.
4. To find the exact amount of revision, based on the difference found in 3, do the time difference x (longitude / 360).
5. Add or subtract this correction amount to or from the noon time of the two days you want to find. (Eastern longitude -, Western longitude +)
To obtain G.M.T., add or subtract L.T. L.T. is also the longitude time and is a number obtained by dividing the longitude by 15. It is also calculated from east longitude - and west longitude +. 4.
Moon's Altitude Correction
Find the hour angle and declination of January 1, 1:20 in U.T.C.
1. basically the same as the solar altitude correction.
2. add or subtract I.E. (Instrumental Difference of Sextant) to or from the sextant altitude and make the correction from that value.
3. From the moon correction tables, obtain the coefficients as for the sun. (Eye height 10 m, elevation about 55°). Note that there are upper and lower limbs, as in the case of the Sun. 4.
4. Find the value of the Moon's Semidiameter (S.D.) from the Nautical Almanac.
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