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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 · Names on the brightest stars and the constellation figures as faint lines, for a sky you draw yourself: a count or a magnitude, the figure under the pointer at full strength, a body that covers part of the sky, and a look set by settings alone

SkyProjectortype

How a page says where a star is: it gets the star's right ascension and declination in degrees and writes the spot on its screen into out. It answers false when the star is not in front of the camera (behind it, or beyond the horizon of the view).

Import it

import type { SkyProjector } from "@johnmorrisdotca/hoshi-stars/sky-labels";

Definition

type SkyProjector = (rightAscension: number, declination: number, out: ScreenPoint) => boolean;

Examples

import type { SkyProjector } from "@johnmorrisdotca/hoshi-stars/sky-labels";

// a page that looks straight at the north celestial pole with the sky 200 pixels across a quarter turn
const project: SkyProjector = (ra, dec, out) => {
  const r = ((90 - dec) / 90) * 200;
  out.x = 300 + r * Math.cos((ra * Math.PI) / 180);
  out.y = 300 - r * Math.sin((ra * Math.PI) / 180);
  return dec > 0;
};
console.log(project(0, 90, { x: 0, y: 0 }));
true

What it prints (run when this page was built)

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