XTE J1650−500

XTE J1650−500 is a binary system containing a stellar-mass black hole candidate and 2000–2001 transient binary X-ray source located in the constellation Ara. In 2008, it was claimed that this black hole had a mass of 3.8±0.5 solar masses, which would have been the smallest found for any black hole; smaller than GRO 1655−40, the then known smallest of 6.3. However, this claim was subsequently retracted; the more likely mass is 5–10 solar masses.

The binary period of the black hole and its companion is 0.32 days.