Celestial Navigation

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CELESTIAL NAVIGATION Z . PN Q HW HE PS Q’ Z’ CELESTIAL SPHERE CELESTIAL SPHERE RELATION BETWEEN DECLINATION & POLAR DISTANCE • DECLINATION IS PARALLEL TO THE EQUINOTIAL, EITHER N DECLINATION OR S DECLINATION. THE DECLINATION STARTS FROM QQ’ UPTO PN THE DECLINATION MEASURED ON THE H.B MERIDIAN NORTH & SOUTH POLE. STARTING FROM THE QQ’ 90 N & 90 S • THE CELESTIAL SPHERE HAS N 90⁰ DECLINATION N MERIDIAN 90⁰ DECLINATION S POLAR DIST. Q’ DECLINATION N Q • DECLINATION S • EQUINOTIAL IS A GREAT CIRCLE S PS POLAR DISTANCE IS THE DISTANCE FROM VISIBLE POLE TO H.B DECLINATION + POLAR DISTANCE = 90 VERTICAL CIRCLE • PRIME VERTICAL CIRCLE WHICH JOINS Z TO Z’ PASSING BY E & W OVER HORIZON Z PN Q VERTICAL CIRCLE IS A GREAT CIRCLE JOINNING ZZ’ E TO THE HORIZON ’ N W S’ PRINCIPAL VERTICAL CIRCLE Q PS JOINNING ZZ’ PASSING BY PN PS &NS ALSO CALLED THE OBSERVER MERIDIAN Z’ E VIEW RELATION BETWEEN ZENITH DISTANCE & ALTITUDE • ZENITH & NADIR ARE THE VERTICAL HH’ TO ZENITH = 90⁰ POINTS OVER THE OBSERVER ZENITH HH’ TO NADIR = 90 PN ZENITH&NADIR IS A GREAT CIRCLE PRIME JOINS THE ZENITH WITH NADIR. VERTICAL CIRCLE ZENITH DIST ZENITH & NADIR MERIDIAN W ’ TO HORIZON HH’ ALTITUDE NH SH’ THE HEVINLY BODY ALTITUDE MEASURED E ALTITUDE ON THE ZZ MERIDIAN STARTING FROM THE HH’. ZENITH DIST THE REST OF THE MERIDIAN IS PS THE ZENITH DISTANCE OF THE HEAVINLY BODY NADIR ALT + Z.D = 90 THE AZIMUTH • Ѳ AZIMUTH Z IS THE ANGLE AT PN ZENITH BETWEEN Ѳ Ѳ VERTICAL CIRCLE PRINCIPAL VERTICAL CIRCLE` TO X VERTICAL CIRCLE OF E 60 PRINCIPAL VERTICAL CIRCLE H,B N S 70 • X = S60E Q W OR X = N120E SEMI OR X = 120⁰ T• Y Y = N70W PS OR Y = N070W OR Y = 29O ⁰ T Z’ POLAR &DECLINATION ZENITH DISTANCE & ALLTITUDE • . EQUATORIAL PROJECTION HORIZON PROJECTION POLAR DISTANCE PN ZENITH ZENITH DISTANCE ZENITH PN ALTITUDE DECLINATION’ E Q Q’ N S W NADIR PS PS NADIR LATTITUDE OF THE OBSERVER & ALTITUDE OF THE POLE • .EQUATORIAL PROJECTION QZ = NPN PN LAT OBSERVER = ALTITUDE OF POLE Z N PROVING 30 60 Q PN = 90 Z N = 90 60 Q Q’ S Z’ PS CELESTIAL COORDINATES CELESTIAL COORDINATES GREENWICH HOUR ANGLE GHA • GHA GREENWICH HOUR ANGLE • IS THE ANGLE AT THE POLES THAT LIES BETWEEN THE GREENWICH PN UPPER MERIDIAN Z & THE H.B MERIDIAN G GHA MEASURED IN W DIRECTION. GHA RANGE 360⁰. GHA IS ALLOCATED ACCORDING TO W THE TIME. Q’ Q E PS Z’.

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