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Star's Calculation
How to Calculate the Star's Hour Angle and Declination (Sirius)
Find the hour angle and declination of January 1, 1:20 in U.T.C.
1. Find E in the Nautical Almanac. For fixed stars, only 0:00 is shown because of little change.
2. Since the amount of change is the same for E＊ of all fixed stars, obtain the corrected value for the relevant time from the P.P. distribution table in the Appendix and add it.
3. The hour angle can be easily obtained by adding the observation time (U.T.C.) to E＊ obtained in 2.
The obtained time angle is in hours, so if you want to obtain it in angular units, just multiply it by 15.
5. In the case of equatorial latitude, the value is obtained from the Nautical Almanac as it is, since it does not change much in daily units. There is no subsequent correction.
How to calculate the Star's midday time.(Sirius)
Find the midday time of January 1, 165°E 1:20:00 U.T.C.
1. subtract from 24:00, since it is not always close to 12:00 like the sun.
2. since the observation time is 10:00 U.T.C., we find the 10:00 EP from the Nautical Almanac.
3. This gives us L.M.T. If we want to find G.M.T., we can add or subtract L.T. L.T. is also the longitude time, which is a number obtained by dividing the longitude by 15. It is also calculated by East Longitude - and West Longitude +.
4. On the column of each planet, you can also get the approximate noon time of the day. (L.M.T.)
Star's Altitude Correction (Sirius)
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 the I.E. (instrumental difference of the sextant) from the sextant altitude and make the correction from that value.
3. From the planet and star correction tables.
Find the coefficients as in the case of the Sun. (Eye height 7m, elevation about 55°).
No.4 Correction is not necessary for stars because their distance is quite large and the parallax is negligible.
5. No.5 correction is a correction based on the difference between air and water temperature. Take the difference between air and water temperature and find the number of corrections from the table.
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