Sidereal Time
GET /v1/sidereal-time — Get Greenwich and local sidereal time.
Sidereal Time
Compute Greenwich Apparent Sidereal Time (GAST) and optionally Local Sidereal Time (LST) for a given moment.
Sidereal time measures the rotation of the Earth relative to the stars rather than the Sun. It's used to determine which stars and degrees are on the meridian and horizon at a given location.
GET /v1/sidereal-time
POST /v1/sidereal-timeCredit cost: 1
Parameters
| Parameter | Type | Required | Default | Description |
|---|---|---|---|---|
datetime | string | One of datetime or jd | — | ISO 8601 UTC datetime |
jd | number | One of datetime or jd | — | Julian Day in UT1 |
lon | number | No | — | Observer longitude in degrees (if provided, LST is included) |
Response
{
"data": {
"gast_degrees": 11.5234,
"gast_hours": 0.7682,
"lst_degrees": 337.5234,
"lst_hours": 22.5015
},
"meta": { "..." }
}| Field | Type | Description |
|---|---|---|
gast_degrees | number | Greenwich Apparent Sidereal Time in degrees (0–360) |
gast_hours | number | GAST in hours (0–24) |
lst_degrees | number | Local Sidereal Time in degrees (only if lon provided) |
lst_hours | number | LST in hours (only if lon provided) |
Examples
curl "https://api.morphemeris.com/v1/sidereal-time?datetime=2024-03-20T12:00:00Z&lon=-74.006" \
-H "Authorization: Bearer morphemeris_live_YOUR_KEY"const res = await fetch(
"https://api.morphemeris.com/v1/sidereal-time?datetime=2024-03-20T12:00:00Z&lon=-74.006",
{ headers: { Authorization: "Bearer morphemeris_live_YOUR_KEY" } }
);
const data = await res.json();import requests
res = requests.get(
"https://api.morphemeris.com/v1/sidereal-time",
params={"datetime": "2024-03-20T12:00:00Z", "lon": -74.006},
headers={"Authorization": "Bearer morphemeris_live_YOUR_KEY"},
)
data = res.json()