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NGC 3998

Set a site to see tonight's sky

When NGC 3998 is up, how long it stays usable and when it is in season all depend on where you observe from. Set your site and this page adds tonight's answer and its year.

Set it on Tonight

The science

What you are looking at

In one sentence

A gravitationally bound system of stars, gas and dust.

Class explainer for galaxy (catalogue type).

The facts

NGC 3998 is a galaxy in Ursa Major. SIMBAD gives its distance as 14.19 Mpc — ≈ 46,280,000 ly from 7 measurements. The light reaching us from it now left it about 46.3 million years ago, after the dinosaurs and before the ice ages. SIMBAD measures it at 3.1′ × 2.5′ on the sky — 10% of the full Moon's width. At that distance, that angle means it is roughly 41,800 light-years across. Framing uses its catalogue size instead: 2.8′. It is receding from us at about 1,070 km/s (redshift z = 0.0036). Its morphological type is SA. It shines at magnitude 11.3.

Sources: AstroBrain catalogue; CDS/SIMBAD astronomical database, Strasbourg (SIMBAD record NGC 3998 · distance from 2016AJ....152...50T). Contains information from SIMBAD, which is made available here under the Open Database License (ODbL). Download the SIMBAD-derived data.

For scale

Angular size, as it would sit on your sky.

Milky Way · ~100,000 lyNGC 3998 · ~41,800 ly

True width compared with our Galaxy's disc (≈100,000 ly, a round figure).

The same patch of sky in visible light

Sky image
Observatory photos and open-licence sky surveys.
Credits on each image.

Neighbours in the sky

Sky maths: apparent positions with refraction, one-minute steps; usable = full astronomical dark, at least 30° up and clear of your skyline. Survey images: CDS, Strasbourg (DSS2 and other surveys). Science: SIMBAD. The hours, heights and Moon on this page use no weather forecast; the rank is this target’s place in the Targets list, whose score also counts the cloud forecast when there is one.

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