Celestial Coordinates. Junior Navigation Chapter 5. Light List for the Sky. Junior Navigation Chapter 6. Selecting DIP Correction. HE 14.1ft corr 3.6’ HE 14.4 ft corr 3.7’ HE 14.9ft corr 3.7’. 14 . 4.
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HE 14.1ft
corr 3.6’
HE 14.4 ft
corr 3.7’
HE 14.9ft
corr 3.7’
14.4
If an entry falls on an exact number in these tables, use the upper correction (“upper” means the correction that is physically higher on the page).
2
Define declination, hour circle, GHA, and LHA
Understand how the GP of a body is located by celestial coordinates, and relationships among hour angles
Obtain GHA and declination of the sun from the Nautical Almanac
Calculate LHA and declination from Nautical Almanacdata
3
To obtain a celestial LOP you need:
Ho, altitude of celestial body you observed
Hc, altitude you calculated from your DR
To calculate Hc, you need to know LHA & Dec
4
Latitude – measured from equator along a meridian of longitude, N or S, to maximum of 90º
Longitude– measured from prime meridian along a parallel of latitude, E or W, to a maximum of 180º
Coordinates?
GP
5
Coordinates
Starting Points
Great Circles
GHA
Dec
LHA
Celestial Equator
Greenwich Celestial Meridian
Hour Circle
Parallel of Declination
Greenwich Hour Angle
Declination
Local Hour Angle
GP
(longitude) measured along the celestial equator West to maximum of 360º
(latitude) measured along hour circle from equator, N or S, to maximum of 90º
6
LHA  need to compute local hour angle of body
Relationship between LHA and GHA is defined as:
(cos LHA x cos Lat x cos Dec) + (sin Lat x sin Dec) = sin Hc
LHA = GHA – West Longitude
or
LHA = GHA + East Longitude
7
M
Lo W
GHA
LHA
LHA
GHA
Lo W
m
15º
30º
G
45º
45º
120º
60º
75º
LHA = GHA 120º – Lo 45º W
LHA = 75º
g
8
M
Lo E
LHA
GHA
Lo E
m
15º
30º
G
45º
45º
315º
60º
300º
75º
285º
LHA = GHA 270º + Lo 45º E
LHA = 315º
270º
90º
255º
105º
LHA
240º
120º
GHA
225º
135º
270º
150º
210º
g
165º
195º
180º
9
M
LHA = GHA 90º – Lo 150º W
LHA = 300º
+ 360º
GHA 450º– Lo 150º W
m
g
Lo W
150º
GHA
90º
LHA ?
G
10
When sun directly over Observer’s Meridian:
Details in Chapter 9
Sun reaches its maximum altitude
Body is
due North or South
Lo = GHA LHA = 000º
Lo W
GHA
M
g
G
11
m
An observer sees the sun directly overhead,
Ho 90º00.0’
Nautical Almanac lists Sun GHA as 298°
and Sun’s Dec is 20° N
What is your latitude and longitude?
Since Dec = 20°N, then Lat = 20°N
GHA of the sun > 180°, so GP of sun is East Lo
GHA of the sun 360° – 298° = 62° E
12
2013
2013 NAUTICAL ALMANAC COMMERCIAL EDITION
NAUTICAL ALMANAC
2013 COMMERCIAL EDITION
JAN 1 2013 THROUGH JAN 1 2014
13
2013 JANUARY 10, 11, 12 (THU., FRI., SAT.)
THURSDAY
THURSDAY
LEFT PAGE
GHA for Aries, and the GHA & Dec plus Magnitude, SHA, & Mer. Pass. for the four Navigational Planets,
and the SHA & Dec for the 57 Navigational Stars
FRIDAY
FRIDAY
Sun or moon symbols: continuous above horizon continuous below horizon twilight lasts all night
SATURDAY
SATURDAY
The Daily Pages
2013 JANUARY 10, 11, 12 (THU., FRI., SAT.)
RIGHT PAGE
GHA & Dec for Sun and Moon plus times for nautical and civil twilight, sunrise, moonrise, sunset, moonset, and time of meridian passage for sun and moon.
14
Two minutes per page
15
Calendars – Public holidays by country; religious holidays for United States; moon phase calendar, Julian calendar
Eclipses
Standard times throughout the world
Star charts
Polaris tables
Sight reduction procedures
Sight reduction tables (NASR method)
Conversions of arc to time
Altitude correction tables for the moon
16
On 10 May you make an observation of the sun from St. Paul, at 17 – 34 – 37 WT and your WE is 8 sec slow
10 May 2012
17 – 34 – 37
00 – 08
+
17 – 34 – 45
5
+
22 – 34 – 45
10 May 2012
18
IGNORE
m 34
SUN PLANETS
ARIES
MOON
22
8 41.9
8 40.5
8 16.8
41
8 40.3
8 41.7
8 16.5
8 17.0
8 40.8
8 42.3
34 45
42
8 41.0
8 42.4
8 17.3
43
44
8 41.3
8 42.7
8 17.5
8 17.7
8 41.5
8 42.9
45
92 14 5
8 18.0
8 41.8
8 43.2
46
8 42.0
8 18.2
8 43.4
47
8 43.7
8 42.3
8 18.5
48
49
UT is 22 – 34 – 45 and longitude is 92º 14.5’ W
CALCULATE
SECOND PAGE
FIRST PAGE
1
150 55 0
4
8 41 3
IGNORE
2
22
17 49 8
IGNORE
3
?
159 36 3
?
0 6
+
5
?
–
0 3
+
?
67 21 8
?
17 50 1
19
IGNORE
?
10
328 03 0
?
9 33 0
38 12
IGNORE
?
10
0 26 0
IGNORE
?
?
?
337 36 0
1 0
–
?
?
34 33 3
–
0 6
–
?
?
303 02 7
0 25 4
21
IGNORE
?
12
358 07 8
?
9 32 5
38 10
IGNORE
?
12
0 00 3
IGNORE
?
?
?
367 40 3
1 0
–
?
?
34 33 3
–
0 6
–
?
?
333 07 0
0 00 3
22
On 17 August, from the point at Bayport Marina, you observe the LL of the sun at WT 085712 DST; WE is 1min 08sec slow; recording a sextant height of 27°35.2’; IE reading is 53.4’ off the arc; HE is 22.0ft and distance to far shore is 0.5nm
GPS reads N45°00.170\' W092°46.534\'
Complete the upper part of the SR96 (USPS Sight Reduction Form), calculating LHA, Dec, Ho, and draw time diagram.
20
18
16
14
12
10
8
6
4
2
READY FOR YOUR ANSWERS?
23
1
17 August
22 0
Sun LL
085712
27 35 2
45 00 2
108
+
92 46 5
6 6
085820
25 1
5
+
6 6
25 1
135820
18 5

17 August
27 16 7
g
G
14 2
14 00 5
13
20
14 35 0
58
zm
13
13 17 4
14 2 0 0
28 35 5
14 2
0 8
+

92 46 5
0 8


27 30 9
295 49 0
13
16 6
NEXT WEEK bring calculator
Ds = (0.4156 x d) + [0.5658 x (h/d)] Ds = (0.4156 x 0.5) + [0.5658 x (22/0.5)] Ds = 0.2078 + (0.5658 x 44) Ds = 0.2078 + 24.8952 Ds = 25.103
Hc 27 31.3’ Ho 27 30.9’
24
1. The coordinates of the GP of the sun are: Lat 7° 09.5\' S, Lo 150° 04.2\' E.
a. What are the GHA and declination of the sun at this time?
GHA = 209° 55.8\' [GHA = 360°  Lo E]
Dec = 7° 09.5\'S
b. If the LHA of the sun at the same time is 48°32.1\' what is the observer\'s Lo?
Lo = 161°23.7\' W [Lo W = GHA  LHA]
25
2. You have determined your position by GPS to be Lat 23° 01.8\' N, Lo 76° 56.3\'. You look up and see the sun directly overhead.
What are the Declination, GHA, and LHA of the sun at this time?
Declination of the sun: 23° 01.8\'N
GHA of the sun: 76°56.3\'
LHA of the sun: 000°
26
4. Fill in the blanks in the following statements about celestial coordinates:
a. __________is the angular distance of the GP of a body north or south of the equator.
b. ___________________is the angular distance from the Greenwich meridian westward to the hour circle of a body.
c. ______________ is the angular distance from an observer\'s local meridian westward to the hour circle of a body.
Declination
Greenwich Hour Angle
Local Hour Angle
28
5. When finding declination of the sun from the Nautical Almanac, a d correction must be determined.
a. Trueb. False.
29
6. Using the Excerpts from the Nautical Almanac for August 24, will the d value be entered on the Sight Reduction form as positive or negative?
a. positiveb. negative
30
7. Using the Excerpts from the Nautical Almanac, what is the declination of the sun for 1400 UT on March 30?
Declination of the sun = _________
3° 57.0\' N
31
8. Declination of the Sun is equal to the Hour Declination _____________ the d correction.
a. plusb. minusc. plus or minus
plus or minus
32
9. The local hour angle (LHA) is found by __________ DR Lo(W) from the GHA of the Sun.
a. addingb. subtracting
subtracting
33