HARPS RV time series for GJ 1137. The data are divided into two subsets due to known instrumental RV offsets introduced by the HARPS optical fibre upgrade in May 2015. Purple circles represent RVs obtained before the fibre change, while green squares correspond to data taken after the upgrade. The observed RV variations are primarily driven by the signal of the known Saturn-mass exoplanet GJ 1137 b, with a period of P = 144.7 d. In addition, the RV data reveals a second, long-term signal from a potential Jovian planet with a minimum mass of approximately 1.3 M_J and a period P = 5640 ± 240 d. Subsequent analysis attributes this long-term signal to stellar magnetic activity.