CAPT. MANALO, M.E BSMT
COMPASS ERROR BY STAR OBSERVATION CORRECTING
(add EAST / subtract WEST)
Date
Stop Watch Magnetic Compass C
LMT Deviation D
Long in Time Corrected Mag. Compass M
GMT/UTC Variation (use original name) V
True Course T
Position: Lat.
Long. NOTES:
Gyro bearing
Gyro Course A = Tan Lat / Tan LHA
Magnetic Course (named opposite of Lat. Except when LHA is
between 90ᵒ - 270ᵒ)
GHA of ɤ B = Tan Declination / Sin LHA
Inc and corr (always+) (named same as declination)
GHA of ɤ (When solving for A and B, disregard the negative
Long. (E+ / W-) sign)
LHA ɤ
C = A+B ( if A and B have same name add)
C= A – B (if A and B have different names
Name of subtract the lesser value from the greater value
SHA of and take the name of the greater value)
Declination of
Tan Z = 1 / ( C x Cos Lat)
1
LHA ɤ
Z = Tan -1 C X Cos Lat
SHA of (always+)
LHA Name azimuth angle (Z) by: Name of C and LHA
- If LHA is between 0 to 180 name is West
A - If LHA is between 180 to 360 name is East
B
To get True bearing (Zn):
C
Apply the operation of quadrants to the value of Z.
Z
Zn
N
True bearing TB
Gyro bearing GB IV - 360 I As is
Gyro error GE
W E
Gyro Course GC
True Course TC II - 180
III + 180
Magnetic Course MC
Magnetic Error ME
Variation (reverse the name) VAR S
Deviation DEV
NAV 4 CELESTIAL NAVIGATION
, CAPT. MANALO, M.E BSMT
GUIDELINES on using the form:
Date Date of actual observation
Stop Watch Applied to LMT to get the actual time of
LMT observation
Long in Time Divide the Longitude by 15ᵒ to get Longitude in
time and apply to LMT to get the GMT/ UTC of
GMT/UTC
observation
Can be taken directly as UTC or GMT
Position: Lat. Position of the observer when taking the
Long. observation.
Gyro bearing Bearing of the celestial object
Gyro Course Gyro Course and magnetic course of the vessel
Magnetic Course when taking the observation
Taken from the Nautical almanac using hour of the UTC
GHA of ɤ Taken from the increments and correction table of the
Inc and corr (always+) Nautical Almanac using the minutes and seconds of UTC
Corrected GHA of Aries
GHA of ɤ
Apply Long by adding if Long is East and subtract if
Long. (E+ / W-)
West. The answer will be the LHA of Aries
LHA ɤ
Star from which observation is taken
Name of Taken from the Nautical Almanac for the star used
SHA of for the observation (found at the column for
Declination of STARS) (if declination is negative value the
direction is South)
LHA ɤ
Always add to get the value of LHA of the Star
SHA of (always+)
LHA
True bearing of the Star
True bearing (Zn) TB Gyro bearing taken by azimuth circle
Gyro bearing GB Difference of TB-GB. (named E or W: Compass BEST
Gyro error GE error West/ Compass LEAST error EAST)
Gyro Course GC Gyro course during the time of observation
True Course TC Gyro Course applied by Gyro error ( Add E error /
Magnetic Course MC subtract W error)
Magnetic Error ME Magnetic course during the time of observation
Variation VAR (always reverse Difference of TC – MC (named E or W: Compass
the name) BEST error West/ Compass LEAST error EAST)
Deviation DEV Same name add, different names subtract
Named according to which ever has greater value
between ME and VAR.
Magnetic Compass C Magnetic course during the time of observation
Deviation D Add if deviation is East subtract if West
Corrected Mag. Compass M
Variation V (use original name) Add if Var is East / Subtract if Var is West
True Course T Should be the same as the True course above
NAV 4 CELESTIAL NAVIGATION
COMPASS ERROR BY STAR OBSERVATION CORRECTING
(add EAST / subtract WEST)
Date
Stop Watch Magnetic Compass C
LMT Deviation D
Long in Time Corrected Mag. Compass M
GMT/UTC Variation (use original name) V
True Course T
Position: Lat.
Long. NOTES:
Gyro bearing
Gyro Course A = Tan Lat / Tan LHA
Magnetic Course (named opposite of Lat. Except when LHA is
between 90ᵒ - 270ᵒ)
GHA of ɤ B = Tan Declination / Sin LHA
Inc and corr (always+) (named same as declination)
GHA of ɤ (When solving for A and B, disregard the negative
Long. (E+ / W-) sign)
LHA ɤ
C = A+B ( if A and B have same name add)
C= A – B (if A and B have different names
Name of subtract the lesser value from the greater value
SHA of and take the name of the greater value)
Declination of
Tan Z = 1 / ( C x Cos Lat)
1
LHA ɤ
Z = Tan -1 C X Cos Lat
SHA of (always+)
LHA Name azimuth angle (Z) by: Name of C and LHA
- If LHA is between 0 to 180 name is West
A - If LHA is between 180 to 360 name is East
B
To get True bearing (Zn):
C
Apply the operation of quadrants to the value of Z.
Z
Zn
N
True bearing TB
Gyro bearing GB IV - 360 I As is
Gyro error GE
W E
Gyro Course GC
True Course TC II - 180
III + 180
Magnetic Course MC
Magnetic Error ME
Variation (reverse the name) VAR S
Deviation DEV
NAV 4 CELESTIAL NAVIGATION
, CAPT. MANALO, M.E BSMT
GUIDELINES on using the form:
Date Date of actual observation
Stop Watch Applied to LMT to get the actual time of
LMT observation
Long in Time Divide the Longitude by 15ᵒ to get Longitude in
time and apply to LMT to get the GMT/ UTC of
GMT/UTC
observation
Can be taken directly as UTC or GMT
Position: Lat. Position of the observer when taking the
Long. observation.
Gyro bearing Bearing of the celestial object
Gyro Course Gyro Course and magnetic course of the vessel
Magnetic Course when taking the observation
Taken from the Nautical almanac using hour of the UTC
GHA of ɤ Taken from the increments and correction table of the
Inc and corr (always+) Nautical Almanac using the minutes and seconds of UTC
Corrected GHA of Aries
GHA of ɤ
Apply Long by adding if Long is East and subtract if
Long. (E+ / W-)
West. The answer will be the LHA of Aries
LHA ɤ
Star from which observation is taken
Name of Taken from the Nautical Almanac for the star used
SHA of for the observation (found at the column for
Declination of STARS) (if declination is negative value the
direction is South)
LHA ɤ
Always add to get the value of LHA of the Star
SHA of (always+)
LHA
True bearing of the Star
True bearing (Zn) TB Gyro bearing taken by azimuth circle
Gyro bearing GB Difference of TB-GB. (named E or W: Compass BEST
Gyro error GE error West/ Compass LEAST error EAST)
Gyro Course GC Gyro course during the time of observation
True Course TC Gyro Course applied by Gyro error ( Add E error /
Magnetic Course MC subtract W error)
Magnetic Error ME Magnetic course during the time of observation
Variation VAR (always reverse Difference of TC – MC (named E or W: Compass
the name) BEST error West/ Compass LEAST error EAST)
Deviation DEV Same name add, different names subtract
Named according to which ever has greater value
between ME and VAR.
Magnetic Compass C Magnetic course during the time of observation
Deviation D Add if deviation is East subtract if West
Corrected Mag. Compass M
Variation V (use original name) Add if Var is East / Subtract if Var is West
True Course T Should be the same as the True course above
NAV 4 CELESTIAL NAVIGATION
