Problem 1
On 17 March 1981, your 0520 OR position is LA T 27- 23.0' N, LONG 39° 42.0' W. At this time you observe an unidentified star bearing 270° T with an observed altitude of 46° 30.2', The chronometer reads 08h 22m 15s, and is 01 m 45s fast. What star did you observe?
A. Altair
B. Alkaid
C. Arcturus
D. Deneb
STEP 1
Using GMT, and Greenwich date of observation, enter Nautical Almanac and record tabulated hourly value of GHA ( ARIES ).
STEP 2
Turn to the yellow pages of the Nautical Almanac, and find the "20 minute page," enter with "30-seconds." Then under the "ARIES" column find the increase in the GHA (1') since the last tabulated (hourly) value, flence 5° 08.3'. This is your M&S correction and enter this in your format.
BODY ?
DATE 17 MAR. 1981
DR LAT 27-23.0 N
DR LONG 39-42.0 W
Hs
IE
Hs
Dip
Ha
ALT Corr
Ho 46-30.2
ZT 0520
ZD +3
GMT 17th 0820
CT 08h 22m 15s
CE 1m 45s fast
CCT 17th 08h 20m 30s
GHA (Aries) 294-48.6
M&S (Aries) 5-08.3
SHA
V
GHA (Aries) 299-56.9
DR LONG - 39-42.0 W
LHA (Aries) 260-14.9
TAB DEC
d corr
DEC
STEP 3
Add the GHA (ARIES) and M&S to get the GHA (ARIES).
STEP 4
Bring down your DR longitude and enter it in your form. The rule is:
LHA (ARIES) = GHA (ARIES) + EAST LONGITUDE - LHA (ARIES) = GHA (ARIES) - WEST LONGITUDE .
So, we subtract our DR longitude to get the LHA (ARIES).
STEP 5
To use the star finder, select the blue template nearest your DR latitude, hence, 25°N and place it on the northern side of the white star finder. You should have the north side of the blue template matched up with the north side of the white star finder,
Remember to ensure that the proper side of the template is UP, hence, north to north , south to south.
STEP 6
Rotate the blue template until the 0° to 180 arrow on the template is over the LHA of 260 degrees on the base plate. The stars or planets that are available to you at that time, will be under the grid system of your blue template.
STEP 7
Locate the bearing of 270 T on the inner edge of the grid.
STEP 8
Using the Ho as the approximate altitude 46 degrees go up from the bearing of 270 degrees
to altitude of 46 degrees and you will find the unknown star "ARCTURUS".
After identifying the star, you would have to work out the sight by starting over again on your form.
