Lunar Libration Geocentric and Topocentric libration
Use the lunar-libration
end point to obtain either geocentric or topocentric lunar libration values.
Request format
The lunar-libration
end point requires a date, and optionally accepts an observer latitude and longitude:
Copy axios ({
"method" : "GET" ,
"url" : "https://api.radiantdrift.com/lunar-libration/[DATE_TIME]" ,
"params" : {
[ "obs" : "[LAT,LNG]" ]
}
})
Copy curl "https://api.radiantdrift.com/lunar-libration/[DATE_TIME][?obs=[LAT,LNG]]
Example 1: without observer location
The following request returns the lunar libration for March 20 2015 at 10:11:57.7 UTC:
Copy GET https://api.radiantdrift.com/lunar-libration/2015-03-20T10:11:57.7Z
The expected response is:
Copy {
"query" : {
"name" : "lunar-libration" ,
"date" : "2015-03-20T10:11:57.700Z"
} ,
"response" : {
"physicalObservations" : {
"physicalLibration" : {
"lat" : 0.03829045 ,
"lng" : -0.03277045
} ,
"opticalLibration" : {
"lat" : -1.22533368 ,
"lng" : 1.2851531
} ,
"totalLibration" : {
"lat" : -1.18704323 ,
"lng" : 1.25238265
} ,
"selenographicPosition" : {
"lat" : 0.26167655 ,
"lng" : 180.87616357
} ,
"selenographicColongitude" : 269.12383643 ,
"positionAngle" : 335.07160049
}
}
}
Example 2: with observer location
If the observer location is given, the end point additionally calculates the total topocentric lunar libration. For example, in Svalbard in March 2015 for the total solar eclipse:
Copy GET https://api.radiantdrift.com/lunar-libration/2015-03-20T10:11:57.7Z?obs=78.222133,15.650467
Expected response:
Copy {
"query": {
"name": "lunar-libration",
"date": "2015-03-20T10:11:57.700Z",
"observer": {
"lat": 78.222133,
"lng": 15.650467
}
},
"response": {
"physicalObservations": {
"physicalLibration": {
"lat": 0.03829045,
"lng": -0.03277045
},
"opticalLibration": {
"lat": -1.22533368,
"lng": 1.2851531
},
"totalLibration": {
"lat": -1.18704323,
"lng": 1.25238265
},
"selenographicPosition": {
"lat": 0.26167655,
"lng": 180.87616357
},
"selenographicColongitude": 269.12383643,
"positionAngle": 335.07160049
},
"topocentricLibration": {
"libration": {
"lat": -0.25992041,
"lng": 0.87406513
},
"positionAngle": 335.07397418
}
}
}
The topocentric libration is typically required for the purposes of simulating the appearance of the Moon at a given time/place, and for determining the effect of the lunar limb on solar eclipse circumstances.
Last updated 6 months ago