Swift J2037.2+4151: An absorbed symbiotic X-ray binary in the Galactic plane

We report on new observations of a historical hard X-ray transient Swift J2037.2+4151. Utilising new data, we improved on the localisation of the source, confirming its association with the bright infrared source SSTSL2 J203705.58+415005.3. Based on the near-infrared spectrum and broadband spectral energy distribution, we argue that the optical star in the system is a red giant with T_ Chandra eff K, located at D>5 kpc. Given the nature of the optical star, we confirm that the Swift J2037.2+4151 is another symbiotic X-ray binary residing in the Galactic plane. An analysis of X-ray data, gathered in 2022-2025, shows that the source resides in a low state. This is caused by simultaneous decrease in the accretion rate and a significant (of an order of magnitude) increase in the thickness of the absorption column.