The Geographic Position of a celestial body is the point on the Earth's Surface where the body would be directly overhead (an Alt of 90°). This is primarily used in celestial navigation. This page is intended as a simple example for converting RA/Dec to a GP, positions are only adjusted for Precession, and not nutation, abberation, etc. Additionally the Sun position algorithm is only good to 1 degree.
| Name | Latitude | Longitude | RA (J2000) | Dec (J2000) | RA (of Date) | Dec (of Date) |
| Sun | +014° 21' 16.53" | +091° 41' 03.50" | +02h 23m 21.02s | +014° 14' 26.01" | +02h 24m 43.95s | +014° 21' 16.53" |
| J2000 Origin | +000° 08' 27.50" | +055° 49' 32.24" | +00h 00m 00.00s | +000° 00' 00.00" | +00h 01m 17.87s | +000° 08' 27.50" |
| Acamar | -040° 12' 16.00" | +100° 18' 25.18" | +02h 58m 15.67s | -040° 18' 16.82" | +02h 59m 13.40s | -040° 12' 16.00" |
| Achernar | -057° 06' 30.69" | +080° 09' 48.15" | +01h 37m 42.85s | -057° 14' 12.33" | +01h 38m 38.93s | -057° 06' 30.69" |
| Acrux | -063° 14' 20.63" | -117° 29' 30.04" | +12h 26m 35.90s | -063° 05' 56.73" | +12h 28m 01.72s | -063° 14' 20.63" |
| Adhara | -029° 00' 28.98" | +160° 24' 23.57" | +06h 58m 37.55s | -028° 58' 19.50" | +06h 59m 37.29s | -029° 00' 28.98" |
| Agena | -060° 29' 37.12" | -093° 05' 23.52" | +14h 03m 49.40s | -060° 22' 22.94" | +14h 05m 38.15s | -060° 29' 37.12" |
| Albireo | +028° 00' 51.58" | -011° 33' 47.16" | +19h 30m 43.28s | +027° 57' 34.85" | +19h 31m 44.58s | +028° 00' 51.58" |
| Alcor | +054° 51' 24.24" | -102° 56' 28.77" | +13h 25m 13.54s | +054° 59' 16.65" | +13h 26m 13.80s | +054° 51' 24.24" |
| Alcyone | +024° 10' 54.45" | +112° 44' 59.29" | +03h 47m 29.08s | +024° 06' 18.49" | +03h 48m 59.67s | +024° 10' 54.45" |
| Aldebaran | +016° 33' 34.02" | +124° 50' 41.62" | +04h 35m 55.24s | +016° 30' 33.49" | +04h 37m 22.49s | +016° 33' 34.02" |
| Alderamin | +062° 41' 35.22" | +015° 17' 39.74" | +21h 18m 34.77s | +062° 35' 08.06" | +21h 19m 10.37s | +062° 41' 35.22" |
| Algenib | +015° 19' 27.51" | +059° 08' 12.91" | +00h 13m 14.15s | +015° 11' 00.95" | +00h 14m 32.58s | +015° 19' 27.51" |
| Algieba | +019° 42' 48.79" | -149° 09' 35.81" | +10h 19m 58.35s | +019° 50' 29.36" | +10h 21m 21.33s | +019° 42' 48.79" |
| Algol | +041° 03' 04.82" | +102° 57' 28.20" | +03h 08m 10.13s | +040° 57' 20.33" | +03h 09m 49.60s | +041° 03' 04.82" |
| Alhena | +016° 22' 32.58" | +155° 17' 39.90" | +06h 37m 42.70s | +016° 23' 57.31" | +06h 39m 10.38s | +016° 22' 32.58" |
| Alioth | +055° 49' 22.18" | -110° 42' 58.29" | +12h 54m 01.75s | +055° 57' 35.36" | +12h 55m 07.83s | +055° 49' 22.18" |
| Alkaid | +049° 11' 15.61" | -097° 21' 48.69" | +13h 47m 32.44s | +049° 18' 47.75" | +13h 48m 32.47s | +049° 11' 15.61" |
| Almaak | +042° 27' 01.24" | +086° 52' 01.30" | +02h 03m 53.95s | +042° 19' 47.01" | +02h 05m 27.81s | +042° 27' 01.24" |
| Alnair | -046° 50' 10.36" | +027° 57' 14.47" | +22h 08m 13.99s | -046° 57' 39.51" | +22h 09m 48.68s | -046° 50' 10.36" |
| Alnath | +028° 37' 39.44" | +137° 28' 28.98" | +05h 26m 17.51s | +028° 36' 26.82" | +05h 27m 53.65s | +028° 37' 39.44" |
| Alnilam | -001° 11' 15.75" | +139° 52' 33.91" | +05h 36m 12.81s | -001° 12' 06.91" | +05h 37m 29.98s | -001° 11' 15.75" |
| Alnitak | -001° 55' 52.11" | +141° 00' 38.04" | +05h 40m 45.53s | -001° 56' 33.26" | +05h 42m 02.26s | -001° 55' 52.11" |
| Alphard | -008° 46' 11.17" | -162° 17' 26.95" | +09h 27m 35.24s | -008° 39' 30.97" | +09h 28m 49.92s | -008° 46' 11.17" |
| Alphekka | +026° 37' 53.20" | -070° 33' 34.49" | +15h 34m 41.27s | +026° 42' 52.89" | +15h 35m 45.42s | +026° 37' 53.20" |
| Alpheratz | +029° 13' 52.66" | +057° 55' 32.28" | +00h 08m 23.26s | +029° 05' 25.56" | +00h 09m 41.87s | +029° 13' 52.66" |
| Alshain | +006° 28' 30.26" | -005° 21' 35.98" | +19h 55m 18.79s | +006° 24' 24.35" | +19h 56m 33.32s | +006° 28' 30.26" |
| Altair | +008° 56' 03.03" | -006° 29' 53.06" | +19h 50m 47.00s | +008° 52' 05.96" | +19h 52m 00.18s | +008° 56' 03.03" |
| Ankaa | -042° 09' 57.53" | +062° 22' 54.04" | +00h 26m 17.05s | -042° 18' 21.53" | +00h 27m 31.32s | -042° 09' 57.53" |
| Antares | -026° 29' 09.04" | -056° 45' 27.42" | +16h 29m 24.46s | -026° 25' 55.21" | +16h 30m 57.89s | -026° 29' 09.04" |
| Arcturus | +019° 03' 56.26" | -090° 17' 11.25" | +14h 15m 39.67s | +019° 10' 56.68" | +14h 16m 50.97s | +019° 03' 56.26" |
| Arneb | -017° 48' 21.22" | +138° 57' 47.50" | +05h 32m 43.82s | -017° 49' 20.24" | +05h 33m 50.89s | -017° 48' 21.22" |
| Babcock's star | +055° 43' 21.52" | +036° 47' 24.97" | +22h 44m 07.51s | +055° 35' 21.21" | +22h 45m 09.38s | +055° 43' 21.52" |
| Barnard's star | +004° 41' 32.73" | -034° 44' 01.95" | +17h 57m 48.50s | +004° 41' 36.20" | +17h 59m 03.59s | +004° 41' 32.73" |
| Bellatrix | +006° 22' 14.35" | +137° 07' 26.12" | +05h 25m 07.86s | +006° 20' 58.93" | +05h 26m 29.46s | +006° 22' 14.35" |
| Betelgeuse | +007° 24' 34.60" | +144° 38' 12.79" | +05h 55m 10.31s | +007° 24' 25.43" | +05h 56m 32.57s | +007° 24' 34.60" |
| Campbell's star | +030° 34' 23.84" | -010° 33' 43.26" | +19h 34m 45.23s | +030° 30' 58.94" | +19h 35m 44.84s | +030° 34' 23.84" |
| Canopus | -052° 42' 37.94" | +151° 37' 46.34" | +06h 23m 57.11s | -052° 41' 44.38" | +06h 24m 30.81s | -052° 42' 37.94" |
| Capella | +046° 01' 26.07" | +135° 08' 29.39" | +05h 16m 41.36s | +045° 59' 52.77" | +05h 18m 33.68s | +046° 01' 26.07" |
| Caph | +059° 17' 26.24" | +058° 07' 49.11" | +00h 09m 10.69s | +059° 08' 59.21" | +00h 10m 30.99s | +059° 17' 26.24" |
| Castor | +031° 49' 52.58" | +169° 33' 18.64" | +07h 34m 35.86s | +031° 53' 17.79" | +07h 36m 12.96s | +031° 49' 52.58" |
| Cor Caroli | +038° 10' 54.08" | -110° 11' 40.60" | +12h 56m 01.67s | +038° 19' 06.17" | +12h 57m 13.01s | +038° 10' 54.08" |
| Cyg X-1 | +035° 16' 17.29" | -004° 40' 13.99" | +19h 58m 21.68s | +035° 12' 05.78" | +19h 59m 18.79s | +035° 16' 17.29" |
| Deneb | +045° 22' 18.58" | +006° 04' 30.44" | +20h 41m 25.91s | +045° 16' 49.22" | +20h 42m 17.75s | +045° 22' 18.58" |
| Denebola | +014° 25' 52.43" | -126° 54' 28.21" | +11h 49m 03.58s | +014° 34' 19.42" | +11h 50m 21.84s | +014° 25' 52.43" |
| Diphda | -017° 50' 53.70" | +066° 42' 51.34" | +00h 43m 35.37s | -017° 59' 11.78" | +00h 44m 51.14s | -017° 50' 53.70" |
| Dubhe | +061° 36' 51.03" | -138° 10' 46.89" | +11h 03m 43.67s | +061° 45' 03.72" | +11h 05m 16.59s | +061° 36' 51.03" |
| Enif | +009° 59' 31.77" | +021° 51' 30.17" | +21h 44m 11.16s | +009° 52' 30.04" | +21h 45m 25.73s | +009° 59' 31.77" |
| Etamin | +051° 29' 13.16" | -035° 11' 59.90" | +17h 56m 36.37s | +051° 29' 20.02" | +17h 57m 11.73s | +051° 29' 13.16" |
| Fomalhaut | -029° 29' 10.81" | +040° 15' 34.42" | +22h 57m 39.05s | -029° 37' 20.05" | +22h 59m 02.01s | -029° 29' 10.81" |
| Groombridge 1830 | +037° 34' 39.94" | -125° 55' 35.36" | +11h 52m 58.77s | +037° 43' 07.24" | +11h 54m 17.36s | +037° 34' 39.94" |
| Hadar | -060° 29' 37.12" | -093° 05' 23.52" | +14h 03m 49.40s | -060° 22' 22.94" | +14h 05m 38.15s | -060° 29' 37.12" |
| Hamal | +023° 34' 55.24" | +087° 39' 05.31" | +02h 07m 10.41s | +023° 27' 44.72" | +02h 08m 36.07s | +023° 34' 55.24" |
| Izar | +026° 58' 06.43" | -082° 58' 30.61" | +14h 44m 59.22s | +027° 04' 27.20" | +14h 46m 05.68s | +026° 58' 06.43" |
| Kapteyn's star | -044° 59' 20.89" | +133° 36' 24.47" | +05h 11m 40.58s | -045° 01' 06.29" | +05h 12m 25.35s | -044° 59' 20.89" |
| Kaus Australis | -034° 22' 09.34" | -028° 02' 07.87" | +18h 24m 10.32s | -034° 23' 04.62" | +18h 25m 51.20s | -034° 22' 09.34" |
| Kocab | +074° 03' 06.67" | -081° 50' 00.70" | +14h 50m 42.33s | +074° 09' 19.82" | +14h 50m 39.67s | +074° 03' 06.67" |
| Kruger 60 | +057° 49' 32.71" | +032° 44' 11.35" | +22h 27m 59.47s | +057° 41' 45.15" | +22h 28m 56.48s | +057° 49' 32.71" |
| Luyten's star | +005° 10' 22.55" | +167° 41' 22.53" | +07h 27m 24.50s | +005° 13' 32.83" | +07h 28m 45.22s | +005° 10' 22.55" |
| Markab | +015° 20' 32.11" | +042° 00' 24.33" | +23h 04m 45.65s | +015° 12' 18.95" | +23h 06m 01.34s | +015° 20' 32.11" |
| Megrez | +056° 53' 31.17" | -120° 19' 58.95" | +12h 15m 25.56s | +057° 01' 57.42" | +12h 16m 39.79s | +056° 53' 31.17" |
| Menkar | +004° 11' 17.26" | +101° 24' 10.12" | +03h 02m 16.77s | +004° 05' 23.04" | +03h 03m 36.39s | +004° 11' 17.26" |
| Merak | +056° 14' 45.08" | -138° 39' 41.90" | +11h 01m 50.48s | +056° 22' 56.74" | +11h 03m 20.93s | +056° 14' 45.08" |
| Mintaka | -000° 16' 56.32" | +138° 49' 35.69" | +05h 32m 00.40s | -000° 17' 56.73" | +05h 33m 18.10s | -000° 16' 56.32" |
| Mira | -002° 51' 43.78" | +090° 39' 29.28" | +02h 19m 20.79s | -002° 58' 39.51" | +02h 20m 37.67s | -002° 51' 43.78" |
| Mirach | +035° 45' 17.72" | +073° 17' 21.37" | +01h 09m 43.92s | +035° 37' 14.01" | +01h 11m 09.14s | +035° 45' 17.72" |
| Mirphak | +049° 56' 57.50" | +107° 02' 13.28" | +03h 24m 19.37s | +049° 51' 40.25" | +03h 26m 08.61s | +049° 56' 57.50" |
| Mizar | +054° 47' 37.86" | -103° 15' 54.27" | +13h 23m 55.54s | +054° 55' 31.30" | +13h 24m 56.10s | +054° 47' 37.86" |
| Nihal | -020° 44' 25.09" | +137° 50' 02.59" | +05h 28m 14.72s | -020° 45' 33.99" | +05h 29m 19.89s | -020° 44' 25.09" |
| Nunki | -026° 15' 45.32" | -020° 17' 25.74" | +18h 55m 15.93s | -026° 17' 48.20" | +18h 56m 50.00s | -026° 15' 45.32" |
| Phad | +053° 33' 13.79" | -125° 42' 43.49" | +11h 53m 49.85s | +053° 41' 41.14" | +11h 55m 08.82s | +053° 33' 13.79" |
| Pleione | +024° 12' 44.95" | +113° 10' 32.58" | +03h 49m 11.22s | +024° 08' 12.16" | +03h 50m 41.89s | +024° 12' 44.95" |
| Polaris | +089° 22' 08.37" | +101° 42' 22.12" | +02h 31m 49.08s | +089° 15' 50.79" | +03h 04m 49.19s | +089° 22' 08.37" |
| Pollux | +027° 57' 47.67" | +172° 13' 17.87" | +07h 45m 18.95s | +028° 01' 34.32" | +07h 46m 52.91s | +027° 57' 47.67" |
| Procyon | +005° 09' 55.55" | +170° 39' 45.83" | +07h 39m 18.12s | +005° 13' 29.98" | +07h 40m 38.78s | +005° 09' 55.55" |
| Proxima | -062° 47' 27.82" | -086° 34' 41.68" | +14h 29m 42.95s | -062° 40' 46.14" | +14h 31m 40.94s | -062° 47' 27.82" |
| Rasalgethi | +014° 21' 46.68" | -045° 32' 52.50" | +17h 14m 38.86s | +014° 23' 25.20" | +17h 15m 48.22s | +014° 21' 46.68" |
| Rasalhague | +012° 32' 42.02" | -040° 28' 19.06" | +17h 34m 56.07s | +012° 33' 36.13" | +17h 36m 06.45s | +012° 32' 42.02" |
| Red Rectangle | -010° 39' 00.17" | +150° 47' 30.48" | +06h 19m 58.22s | -010° 38' 14.69" | +06h 21m 09.75s | -010° 39' 00.17" |
| Regulus | +011° 50' 32.77" | -152° 04' 03.31" | +10h 08m 22.31s | +011° 58' 01.95" | +10h 09m 43.50s | +011° 50' 32.77" |
| Rigel | -008° 10' 27.22" | +134° 26' 24.69" | +05h 14m 32.27s | -008° 12' 05.91" | +05h 15m 45.37s | -008° 10' 27.22" |
| Rigil Kent | -060° 56' 30.24" | -084° 06' 32.76" | +14h 39m 36.50s | -060° 50' 02.31" | +14h 41m 33.54s | -060° 56' 30.24" |
| Sadalmelik | -000° 11' 45.01" | +027° 16' 18.86" | +22h 05m 47.04s | -000° 19' 11.46" | +22h 07m 04.98s | -000° 11' 45.01" |
| Saiph | -009° 39' 44.81" | +142° 44' 26.74" | +05h 47m 45.39s | -009° 40' 10.58" | +05h 48m 57.50s | -009° 39' 44.81" |
| Scheat | +028° 13' 10.67" | +041° 45' 03.85" | +23h 03m 46.46s | +028° 04' 58.04" | +23h 04m 59.98s | +028° 13' 10.67" |
| Shaula | -037° 07' 10.17" | -040° 39' 58.37" | +17h 33m 36.52s | -037° 06' 13.76" | +17h 35m 19.83s | -037° 07' 10.17" |
| Shedir | +056° 40' 33.70" | +065° 59' 26.60" | +00h 40m 30.44s | +056° 32' 14.39" | +00h 41m 57.49s | +056° 40' 33.70" |
| Sheliak | +033° 23' 36.63" | -021° 44' 42.10" | +18h 50m 04.79s | +033° 21' 45.60" | +18h 51m 00.91s | +033° 23' 36.63" |
| Sirius | -016° 44' 38.58" | +157° 04' 16.47" | +06h 45m 08.92s | -016° 42' 58.02" | +06h 46m 16.82s | -016° 44' 38.58" |
| Spica | -011° 17' 33.06" | -102° 51' 57.21" | +13h 25m 11.58s | -011° 09' 40.76" | +13h 26m 31.91s | -011° 17' 33.06" |
| Tarazed | +010° 40' 35.89" | -007° 37' 59.28" | +19h 46m 15.58s | +010° 36' 47.74" | +19h 47m 27.77s | +010° 40' 35.89" |
| Thuban | +064° 15' 18.89" | -093° 13' 43.90" | +14h 04m 23.35s | +064° 22' 33.06" | +14h 05m 04.79s | +064° 15' 18.89" |
| Unukalhai | +006° 20' 50.11" | -068° 07' 13.86" | +15h 44m 16.07s | +006° 25' 32.26" | +15h 45m 30.80s | +006° 20' 50.11" |
| Van Maanen 2 | +005° 31' 34.55" | +068° 07' 11.19" | +00h 49m 09.90s | +005° 23' 18.99" | +00h 50m 28.47s | +005° 31' 34.55" |
| Vega | +038° 48' 23.66" | -025° 03' 05.28" | +18h 36m 56.34s | +038° 47' 01.29" | +18h 37m 47.37s | +038° 48' 23.66" |
| Vindemiatrix | +010° 49' 24.38" | -108° 38' 15.24" | +13h 02m 10.60s | +010° 57' 32.94" | +13h 03m 26.70s | +010° 49' 24.38" |
| Zaurak | -013° 26' 14.26" | +115° 18' 13.80" | +03h 58m 01.77s | -013° 30' 30.66" | +03h 59m 12.64s | -013° 26' 14.26" |
| 3C 273 | +001° 54' 45.41" | -116° 53' 49.63" | +12h 29m 06.69s | +002° 03' 08.63" | +12h 30m 24.41s | +001° 54' 45.41" |
//Greg Miller (gmiller@gregmiller.net) https://www.celestialprogramming.com/
//Released as public domain 2022
//All angles input/output in radians
function getGeographicPosition(ra,dec,gst){
const lat=dec;
let lon=ra - gst;
if (lon>2*Math.PI){
lon-=2*Math.PI;
}
if(lon>Math.PI){
lon=lon - 2*Math.PI;
}
if(lon < -Math.PI){
lon=lon+2*Math.PI;
}
return [lat,lon];
}