TABLES AND WORKSHEET FOR WILLIAME BUCKLEY, JR's CELESTIAL NAVIGATION SIMPLIFIED THE DEVELOPMENT OF CELESTIAL NAVIGATION "Navigation can be traced to the Polynesians who realized that certain starsat their zenith passed over certain islands, This enabled them to ‘navigate the Pacific latitudinall, aligning themselves with the appropri- ate star and moving either east or west ‘Medieval Norse navigators valued the Pole Star for measuring, latitudes since it altitude above the horizon was nearly constant. AS time went on they also recognized that laitude could be found by ‘measuring the altitude ofthe sun at its highest point, at noon. Stil ater, European mariners used the planets and stars, and devised almanacs to show the various positions of the celestial Bodies at different times of the year. This provided a reliable guide or finding latitude Longitude, however, could not be accurately determined until the chronometer was developed in the mid eighteenth century, allowing Droper timekeeping at sea. Chronometers became standard equipment for ships, and when the sextant replaced the astolabe, the measure- ‘ment of altitude became more precise. Yet, even with these improve- ‘ments, celestial navigation still meant complicated, spherical rigono- ‘metric solutions. Not unt the development ofthe computer, just before World War I, ‘could the thousands of values be pre-calculated and published in Sight Reduction Tables. Knowledge of simple arithmetic now sufices forthe celestial navigator; with valid Almanacs and Sight Reduction Tables, the modem sailor can determine his position accurately and quickly and yet still fee! a common bond with ancient marine voyagers,1 Date: Watch Time OWT: Corrections: ‘Change to 24-he. system: Watch Error: (+ slow; ~ fat Time Zone Correction: 00:00, Correct GMT: 4. Sextant Altitude (Hs): s Corections Index Error (H: 415) 2 ‘Refraction (Ref) = a “Height of Eye (Dip: a 'SemiDiameter (SD) y Height Observed (Ho) *see tables in back of Almanac see box, lower right comer of each page {assuming you have shot the lower limb) m, te the Almanac, tur to proper date and time (GMI) to get: Declination (Dec. 0s and rough Greenwich Hout Angle (GHAY: oo Tum to “Interpolation of GHA Sun in back of Almanac, and [ADD Increments (extra minutes and seconds of GMT interpolated) E To get the we GHA: a ‘This isthe Geographical Postion (GP) of the sun wv. ‘Assumed Position (AP) Latitude (choose nearest whole number +00" ws Longitude (choose minutes to give a minute (ee LHAY +i To find LHA, tn West Longitudes, subtract —IFAP Long. isles than GHA, subteact AP (com GHA to get LA. ICAP Long. is greater than GHA, add 360° 10 GHA, subteact AP (com GHA. In East Longitudes. add: —The sum of GHA and AP = LHA. {the sum s mare than 360", subiract 360” Local Hour Angle (LHA): SUNSIGHT PROCEDURE tate Sieh Reduction able (1.0. 249), tut section on ‘your AP Latinude, —then tothe subsection on your Dec. (whole degrees only) _—thento the subsection on “Same” or “Contrary Name”. locate your LHA in the far right or let hand column. Look across that line to where it intersects with the column under your Dec. —Write Down 3-part figure that appears there: He d(e— z, ‘Take middle figure (d) 10 Table 5 at back of H.0.249, “Correction o Tabulated Altitude for Minutes of Declination.” Locate that figure across top of table. —Locate your minutes of Dec, down let hand column. Look across that line tothe intersection under the “” figure column _~Add or Subtact those minutes, according tothe sign beside the “d” figure, to He (above) to get He (Computed Altitude : oF Tue Calculated Altitude! : : “ Ted eu Amat acon teflon Chaney iontaeteespeeath Rdetenln) imho "Plrtsapunethonieoe eet Cows { rtna'se ton nan =e =z InSouh FFM ecerban 8h dns t= tere { an stenman iran = 0" 2 ‘aim a= vn ‘On your plot 1. Mark your AR. 2, Take Parallel Rules, and using compass rose to get the Zn bearing, draw alightpenciline from your APin the ditectionof the Zn bearing, 3. Find your Intercept (lt): (the difference between Ho and He) Int... He greater... Away W Ho greater... Toward 4. Using your dividers, measure ofthe Intercept Distance on the Latitude Scale atthe side of the plotting sheet. Plt this distance along the Zn line. Mark that point. 5. Using a triangle, draw a line perpendicular (1) to the Za i sheet, This is vour Line of Position (LOPD 6. Erase he Zane, and label your LOP according the local time ofthe sight ele dive ad pling Baer ail which can be pacha tour local charley O28 poy oe mute nt of hi sn procedure etic, aared he viewer epee hs het bee wing it 7884 AIAN COMMUNICATIONS.340___(OAY 170) GREENWICH P. M. 1975 JUNE 19 (THURSDAY) F t z E azee 28 w GEFEE SA6EE BE0EE 5 23 Seger 88: i. BR IEE as Ee Be Bl es mele st fm t= bales a SR) a ie BeBe RUB Bo) 2 ge Be He ae ae eee eae | SRR) RE an. BRE we See ne 2 BOSEEx Supees ores. w ae oo sucgue scseve Spusce Steves sprit Ba 83) enn 0a" sa Pe Stee | “age toAbe INTERPOLATION OF G.H.A. SUN Hb 23328 BEESS 5TABLE 6.—Refraction “To be subtracted fom sextant altitude ight above ses lov! in thousan of foot ales w[s » =|» =» «[5 © Sentent Gude tut tom At Annie nh US. ed emo, Aaa CORRECTIONS TO BE APPLIED TO MARINE SEXTANT ALTITUDES were | te tn an i_Bo he | OB aden Eee Mucinewon Je |e Borer] ft f2LS pera esas BS sf m8) oat * i StS s Ba we le ae | ia ©S5Sn8 BARRA BRERA RARER RGRAR BAARA Bt LAT 38° Lat 38° WAME AS LATITUDE. INATION (15-207 BEC iSEae AAAS SARRR BGS SSSR RANA RAGE TSIIS SITTS Tatad tom Fe a eta a oo ey db Da at RE RTT ES