NGC 5517

NGC 5517 is a lenticular galaxy in the constellation Boötes about 390 million ly from Earth. It spans roughly 110,000 ly, about the width of our Milky Way. The light reaching us tonight left it about 390 million years ago.

Because its light is 390 million ly from home, you are seeing NGC 5517 as it looked roughly 390 million years ago. The photons left before that much of history had passed, and are only now reaching us. This distance is estimated from the galaxy's redshift, so the lookback time is approximate.

Source: structural data (position, morphology, brightness, redshift) from OpenNGC (CC BY-SA). Recession velocity from RC3 (de Vaucouleurs et al. 1991, via NASA/HEASARC, public domain). Distance computed by gravityfinder from redshift via Hubble's law (H0 = 70 km/s/Mpc).