Skip to the content

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 · Your sky: altitude and azimuth for a place and a moment

HorizontalOptionstype

How to read the position and whether to bend the light.

Import it

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

Definition

interface HorizontalOptions {
    equinox?: "J2000" | "date";
    refraction?: boolean;
    pressureHpa?: number;
    temperatureC?: number;
}

Members

NameTypeDescription
equinox (optional)"J2000" | "date" | undefined

"J2000" (the default) when the position is a catalogue position, which is turned to the equinox of the date first; "date" when it is already the mean equator and equinox of the moment (planets are, from an almanac).

refraction (optional)boolean | undefined

True to lift the altitude by the air's bending of light (Saemundsson's formula, Meeus 16.4): about 0.48 degrees at the horizon, 0.02 at 45 degrees up. Default false, the geometric altitude. Not applied below -1 degree, where the formula stops being true.

pressureHpa (optional)number | undefined

Air pressure in hectopascals for the refraction; default 1010 (a standard sea-level day). Only used with refraction.

temperatureC (optional)number | undefined

Air temperature in degrees Celsius for the refraction; default 10. Only used with refraction.

Examples

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

const options: HorizontalOptions = { refraction: true, pressureHpa: 900, temperatureC: -5 };
console.log(options.refraction);
true

What it prints (run when this page was built)

View sourceEdit on GitHubMade from the source of @johnmorrisdotca/hoshi-stars 0.7.0.