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How to Determine Star Time and Selected Stars Using
Pub 249 Vol I (Selected Stars), Continued
Step
Action
Result
1.
Determine the time of sunset.
1841
2.
Add 30 minutes to the time of sunset (star
1911
time). Find and note the DR position for
1911. For our example we will use
36°14.0'N 069°04'W.
3.
4.
Find GMT of star time 1911. Remember
to find GMT apply the ZD to LMT.
From the left-hand pages of the Nautical
Almanac, find the GHA of Aries.
00h 11m
02 Sep 91
339°39'.7
5.
From the Increments and Corrections pages
find the page with 11m and then find the
value for Aries for 00 seconds.
2°
45'.5
6.
Find the total GHA of Aries by adding the
results from step 4 and 5 together.
Remember to carry over 1 whole degree
whenever the total minutes are greater than
60. Ex. 85 - 60 = 25 carry 1°.
339°39'.7
+ 2 ° 4 5 ' . 5
342°25'.2
7.
Find the LHA of Aries by subtracting west
longitude, or adding east longitude.
342°25'.2
-069°04'.5
273°21'.2
8.
Round off DR lat. and LHA Aries to the
DR lat. = 36° N
closest °.
LHA Aries 273°
9.
Enter Pub 249 on the page for 36° N.
10.
Record the values for Hc and Zn for each
See example
star for LHA Aries for 273° on a
worksheet on next
worksheet.
page.
6-12
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