What is NGC 4993?

A lens-shaped galaxy of old stars in Hydra, where two neutron stars were seen colliding in 2017 — the collision GW170817.

Can you see it?

No small telescope will show you this one; it is here to be understood, not spotted.

Anything light from there tells us is news about 130 million years old.

Why it stands out: Two neutron stars collided in it long ago, and in August 2017 the collision was felt as gravitational waves and then seen in light — the first time both were caught from one event.
What it is: Strictly a lenticular galaxy, the in-between kind that looks like an elliptical: a disc of old stars with no spiral arms, shaped like a lens. Faint shells of stars and a twisted lane of dust round its middle are left from swallowing a smaller galaxy about 400 million years ago.
Its name and its story: Discovered by William Herschel on 26 March 1789.

The numbers