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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 · What you can see tonight: the stars above the horizon of a place and a moment that the Sun's light, the sky's darkness and the air still let through, with the twilight, each star's altitude and azimuth and how easy it is to see

TonightOptionstype

What the sky is like: all of it optional.

Import it

import type { TonightOptions } from "@johnmorrisdotca/hoshi-stars/tonight";

Definition

interface TonightOptions {
    limit?: SkyLimit;
    minAltitude?: number;
    extinction?: number;
    moonPenalty?: number;
    sunAltitude?: number;
    all?: boolean;
}

Members

NameTypeDescription
limit (optional)SkyLimit | undefined

The site's darkness: "city", "suburb", "rural" (the default), "dark" or a limiting magnitude at the zenith.

minAltitude (optional)number | undefined

The lowest altitude counted, in degrees (default 0, the horizon). Extinction takes the stars close to the horizon out whatever this is.

extinction (optional)number | undefined

Magnitudes lost per airmass (default 0.2, the V band at a good low site; 0.3 to 0.4 in haze). Only the part above the zenith's one airmass is taken off, since a site's limit already holds the zenith's.

moonPenalty (optional)number | undefined

Magnitudes the limit falls by, passed in by the caller: the Moon's glare (about 0.5 at a crescent, 2 at the full Moon, 0 when it is down).

sunAltitude (optional)number | undefined

The Sun's altitude in degrees, if you already know it; otherwise it is worked out from the moment.

all (optional)boolean | undefined

Return every star above the horizon, with "not tonight" for those you cannot see, instead of only the ones you can (default false).

Examples

import type { TonightOptions } from "@johnmorrisdotca/hoshi-stars/tonight";

const sky: TonightOptions = { limit: "suburb", minAltitude: 10, extinction: 0.25, moonPenalty: 1 };
console.log(sky.limit);
suburb

What it prints (run when this page was built)

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