GRAVITY: a four-telescope beam combiner instrument for the VLTI

Understand

GRAVITY is an adaptive optics assisted Beam Combiner for the second generation VLTI instrumentation.

• The instrument will provide high-precision narrow-angle astrometry and phase-referenced interferometric imaging in the astronomical K-band for faint objects.
• We describe the wide range of science that will be tackled with this instrument, highlighting the unique capabilities of the VLTI in combination with GRAVITY.
• The most prominent goal is to observe highly relativistic motions of matter close to the event horizon of Sgr A*, the massive black hole at center of the Milky Way.