SIMBAD references

The detection of low-energy counterparts to gamma-ray sources is critical to understanding the nature of the astrophysical systems producing such high-energy emission. We report on Swift-XRT observations at five LHAASO gamma-ray sources with no known low-energy counterpart and scant previous X-ray observations. At four of the five LHAASO targets, we detect no significant X-ray point sources, while at 1LHAASO J1928+1813u we detect a single X-ray source that is likely related to X-ray emission from a local cool stellar system. These results suggest that many X-ray counterparts to LHAASO sources have X-ray flux below ≈10^–13 erg s^–1 cm^–2, or have diffuse X-ray emission not visible in brief observations.