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Hoshi Stars星

The stars you can see without a telescope, with names, colours and distances; the 88 constellations with their lines and boundaries; the Messier objects; and seven map projections to draw them on.

Hoshi is the Japanese word 星 for a star. About the name

Contents

Reference · The whole sky on one wide 2:1 map: galactic or equatorial, Mollweide, Hammer or plate carrée, with lines cut cleanly at the seam

allSkyLinefunction

A line on the sky (a figure's segment, a boundary, a meridian) as runs of points of the picture. The line follows great circles between your points, cut every step degrees so a curve stays smooth, and a line that crosses the seam (the edge, half a turn from the centre) is cut there into two runs that end ON the edge, one at each side, so nothing is drawn across the picture.

Import it

import { allSkyLine } from "@johnmorrisdotca/hoshi-stars/all-sky";

Definition

function allSkyLine(points: readonly SkyPoint[], options: AllSkyOptions, step?: number): AllSkyPoint[][]

Parameters

NameTypeDescription
pointsreadonly SkyPoint[]

The sky positions in degrees, in order (a closed outline repeats its first point).

optionsAllSkyOptions

The picture.

step (optional)number

The longest piece between two points of a run, in degrees; 2 by default.

Returns

AllSkyPoint[][]

One run for a line that stays on its side of the seam, more where it crosses; each has at least two points.

Examples

import { allSkyLine } from "@johnmorrisdotca/hoshi-stars/all-sky";

// Two points either side of the galactic anticentre: the line is cut at the edge
const runs = allSkyLine([{ rightAscension: 84, declination: 30 }, { rightAscension: 100, declination: 30 }], { width: 1000, centre: 0 });
console.log(runs.length);
2

What it prints (run when this page was built)

View sourceEdit on GitHubMade from the source of @johnmorrisdotca/hoshi-stars 0.47.0.