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Reducing Sights Using Pub 249, Continued
OPNAV 3130/32
ACTION
Completed Strip
H.O.249 Air Alm
Form
GHA(h)
Enter the GHA hour value of Aries from
282°
35.1'
the Air Almanac to the nearest 10 minutes.
(See fig. 9-18).
Increment (m/s)
Enter the minutes and seconds value from
1° 35.5'
the interpolation tables of the Air Almanac.
Total GHA
Add GHA(h) and Increments (m/s).
284°
10.6'
+ - 360 (if needed)
a Long (+E, -W)
Enter the assumed DR longitude to arrive at
17° 10.6'W
an even degree of LHA, add east and
subtract west.
LHA
a LAT
Hc
Ho
a
LHA= Total GHA + (v/v or SHA for stars
and planets) +E or -W DR Long.
Enter the assumed latitude.
Enter Pub 249 volume I, with the whole
degree of LHA for REGULUS, record Hc
and Zn (last block). (See fig. 9-19.)
Drop down Ho from above.
Find the difference between Hc and Ho
(remember to use Ho MO To). In this
example, Ho is more than Hc, so it’s
named T for towards.
267°
00.0'
37°N
40°
23.0'
40°
26.4'
T 3.4'
Zn
Enter the Zn (true bearing).
264°
As you can see, using Pub 249 to determine a celestial LOP is a quick
process compared to using Pub 229. Keep in mind that some amount of
accuracy is lost.
9-35
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