At 0800 ZT on 29 June your DR position is LAT 26°00.0'N, LONG 75°29.5'W. Given a chronometer time of 01h 00m 00s, determine the computed altitude (Hc) of the Sun for the assumed position nearest to the above given latitude and longitude.
• Using the 29 June Nautical Almanac page to get the Sun’s GHA and declination at 01h 00m 00s • Choosing the correct assumed position (AP): rounding latitude and longitude to get an LHA that matches the sight reduction tables • Using LHA, latitude, and declination in HO-249/HO-229 to compute Hc
• From the DR longitude and the Sun’s GHA at 01h, what will your LHA be, and how do you adjust the longitude to get an assumed position with a whole-degree LHA? • In which direction (E or W) do you adjust your longitude so that LHA is a whole degree and closest to your DR position? • Once you have AP latitude and LHA, which set of HO tables do you use, and what inputs go into the Hc computation?
• Confirm you are using chronometer time as GMT/UT for entering the Nautical Almanac correctly for 29 June at 01h 00m 00s • Be sure your assumed latitude is the nearest whole degree to the DR latitude (26°00.0’N is already exact) • Verify your assumed longitude produces an LHA that is a whole degree and as close as possible to the DR longitude before entering the sight reduction tables
No comments yet
Be the first to share your thoughts!