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NN 204NN 204Advanced NavigationAdvanced Navigation

Gyro Error by CelestialGyro Error by Celestial

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Gyro Error by CelestialGyro Error by Celestial

Objectives:

1. Understand the importance of determininggyro error and the periodicity in which it is

determined.

2. Review the methods of determining gyro

error when piloting.

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Objectives:

3. Demonstrate the method of determining gyro error by sing ! observing the sn.

". Demonstrate the method of determining gyro error by sing ! observing #olaris.

$. Discss the advantages and limitations ofsing the amplitde e%ation to determine

gyro error.

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Objectives:

&. Discss the best time to observe a body for the prpose of obtaining an amplitde to

determine gyro error.

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Review

'yro error is the difference between the

directions indicated by the gyro compass(

and the respective tre directions.

)est *rror

+f the ship were

on a corse of ,,,pgc( it wold be

pointed left -west

of tre /orth.

*ast *rror

+f the ship were on

a corse of ,,,pgc( it wold be

pointed right -east

of tre /orth.

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Review

0+f 'yro is east( error is *ast.

0+f 'yro is est( error is )est.

'yro bearing 4 *asterly error 5 6re bearing

' 4 * 5 6

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7ethods of determing

'yro *rror6he easiest way of determining gyro error isto compare the compass bearing to an object

with its 8nown -tre bearing. 6hree ways ofdoing this celestially are:

9 *act ;

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Amplitude Method

6his method can be sed when the observed

body is rising or setting( as long as its

declination does not eceed 2" degrees.

6he amplitde is defined as the hori

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Amplitude Method

;dvantages:

1. 6he simplicity of ta8ing an a

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Amplitude Method

6o determine the amplitde angle -; se thefollowing formla:

; 5 arcsin -sin Dec ! cos at

6he reslt( ;( will be epressed with a letter

prefi and sffi. * or ) will precede the

angle( depending on whether the body is rising-*ast or setting -)est. 6he sffi will be

0/ if the body has a north declination( or 0>

if its declination is soth.

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Amplitude Method

6o convert amplitde angle to a tre aoth of )est 2A, @ ;

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olaris

#olaris( called the north star( is always

within 2 degrees of tre north.Balclating the tre a

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!uestions"