Einstein Cross

The Einstein Cross (Q2237+030 or QSO 2237+0305) is a gravitationally lensed quasar
that sits directly behind the centre of the galaxy ZW 2237+030, called Huchra's Lens.
Four images of the same distant quasar (plus one in the centre, too dim to see) appear in the middle of the foreground galaxy due to strong gravitational lensing.

his system was discovered by John Huchra and coworkers in 1985, although at the time they only detected that there was a quasar behind a galaxy based on differing redshifts and did not resolve the four separate images of the quasar.

Some interesting facts:

• The Einstein Cross can be found in Pegasus at 22h 40m 30.3s, +3° 21' 31″.
• The individual images are labelled A through D (i.e. QSO 2237+0305 A),
  the lensing galaxy is sometimes referred to as QSO 2237+0305 G.