Reference · How big a Messier object is on the sky and which way it lies, and its outline
offsetOnSkyfunction
The sky position east and north arc-minutes from a centre, on the tangent plane there (the gnomonic projection, the one that sky photographs and the standard picture header use). Exact on
the sphere; for a few degrees it differs from adding the offsets to right ascension and declination by the shrinking of the meridians.
Import it
import { offsetOnSky } from "@johnmorrisdotca/hoshi-stars/deep-sky/shape";Also exported from: @johnmorrisdotca/hoshi-stars/deep-sky/ngc-ic-shape
Definition
function offsetOnSky(centre: SkyPoint, east: number, north: number): SkyPointParameters
| Name | Type | Description |
|---|---|---|
centre | SkyPoint | The point the plane touches the sky at. |
east | number | Arc-minutes toward increasing right ascension. |
north | number | Arc-minutes toward the north celestial pole. |
Returns
SkyPoint
The sky point, right ascension 0 up to 360.
Examples
import { offsetOnSky } from "@johnmorrisdotca/hoshi-stars/deep-sky/shape";
console.log(offsetOnSky({ rightAscension: 10.68, declination: 41.27 }, 0, 60));{ rightAscension: 10.680000000000007, declination: 42.269898479414394 }What it prints (run when this page was built)