NGC 6522 is a globular cluster of stars in the southern constellation of Sagittarius.

The cluster has an apparent visual magnitude of 8.3 and an angular diameter of 9.4′.

[8] It is highly impacted by reddening due to interstellar dust and the view is heavily contaminated by field stars, making it more difficult identify members.

[9] NGC 6522 is possibly the oldest star cluster in the Milky Way,[10] with an age of more than 12 billion years.

[4] Twenty variable stars have been identified as members of NGC 6522, consisting of eight RR Lyrae, three type II Cepheids, and nine long-period variable stars.