Coordinate Systems

Question 1

what does the Equinoctial System of Coordinates define?

Answer 1

the position of a celestial body - relative to the Equinoctial + the Greenwich Celestial Meridian

Question 2

where can you find the Equinoctial System of Coordinates?

Answer 2

Nortical Almanac

Question 3

what is Declination (Dec)?

Answer 3

the angular distance of a body North or South of the Equinoctial

Question 4

what is Declination equivalent to?

Answer 4

Latitude

Question 5

what is Polar Distance?

Answer 5

the angular distance from the pole to the body

Question 6

what is the complement of Declination?

Answer 6

Polar Distance

Question 7

what is the Greenwich Hour Angle?

Answer 7

angular distance of a body west of the Greenwich celestial merridian

Question 8

what does GHA stand for?

Answer 8

Greenwich Hour Angle

Question 9

what is the GHA approximately equivalent to?

Answer 9

westerly Longitude

Question 10

what does SHA stand for?

Answer 10

Sidereal Hour Angle

Question 11

What is the SHA?

Answer 11

angular distance of a body west of the 1st point of Aries

Question 12

how do you find the GHA of a star?

Answer 12

adding GHA Aries to SHA of the star

Question 13

what is the Geographical Position of a body?

Answer 13

point on Earth’s surface directly below the body

Question 14

what does Latitude equal?

Answer 14

Declination

Question 15

What does Westerly Longitude equal?

Answer 15

Greenwich Hour Angle

Question 16

what does LHA stand for?

Answer 16

Local Hour Angle

Question 17

what is Local Hour Angle?

Answer 17

angular distance of a body west of the observer’s celestial meridian

Question 18

what does the Horizontal System of Coordinates define?

Answer 18

the position of a celestial body relative to the observer

Question 19

what is the PZX triangle?

Answer 19

a spherical triangle on celestial sphere formed by the observer’s meridian PZ, of a body PX and vertical circle through observer’s Zenith + body ZX

Question 20

what are the apexes of the PZX triangle?

Answer 20

• pole P
• observer’s Zenith Z
• body X

Question 21

what are the coordinates of Z in PZX triangle?

Answer 21

Latitude + Longitude

Question 22

what are the coordinates of X in PZX triangle?

Answer 22

Declination + Local Hour Angle

Question 23

what is PZ the complement of in PZX triangle?

Answer 23

Latitude

Question 24

what is PX in PZX triangle?

Answer 24

Polar Distance

Question 25

what is ZX in PZX triangle?

Answer 25

Zenith Distance

Question 26

what is PX the complement of in PZX triangle?

Answer 26

Declination

Question 27

what is ZX the complement of in PZX triangle?

Answer 27

True Altitude

Question 28

what is angle P in PZX triangle?

Answer 28

Local Hour Angle of the body

Question 29

what is angle Z in PZX triangle?

Answer 29

Azimuth

Question 30

what is angle X in PZX triangle

Answer 30

parallactic angle

Question 31

what is the True Angle HX of a body?

Answer 31

angular distance from the observer’s Rational Horizon to the centre of the body

Question 32

what is the PZX of a body?

Answer 32

angle at the observer’s Zenith between the observer’s meridian PZ + vertical circle through the observer’s Zenith + the body ZX

Question 33

what is the True Bearing PZX?

Answer 33

angle at the observer’s Zenith measured clockwise from observer’s meridian PZ - to vertical circle through observer’s Zenith + the body ZX