| Extrasolarplanet: | yes |
| Gliese 15 Ac | |
| Apsis: | astron |
| Discoverer: | Pinamonti et al. |
| Discovery Site: | HARPS-N |
| Discovered: | April 2018 |
| Discovery Method: | Radial velocity |
| Alt Names: | Groombridge 34 Ac, GX Andromedae c |
| Semimajor: | AU |
| Period: | d |
| Star: | Groombridge 34 A |
| Mass: | ≥ |
Gliese 15 Ac (also known as Groombridge 34 Ac, GX Andromedae c) is an exoplanet orbiting the nearby red dwarf star Gliese 15 A (Groombridge 34 A, GX Andromedae), which is part of a binary star system located about 11.6 light-years from the Sun. The planet was first proposed in October 2017 using radial velocity data from the CARMENES spectrograph, combined with measurements from the HARPS and HIRES spectrographs, and its existence was confirmed in April 2018 using HARPS-N data. It has a minimum mass 36 times that of Earth and orbits at around 5.4 astronomical units with a period of 7600days, an orbit which may have been sculpted by interaction with the companion star, Gliese 15 B. As of 2020, Gliese 15 Ac is the longest-period sub-Jovian planet discovered by radial velocity.