A "visiting scientist" refers to a scientist or researcher who temporarily works or studies at another institution or location outside of their usual workplace. Full definition
The lab is building a guest house for visiting scientists inside its perimeter fence. (sciencemag.org)
The research fellowships support high school students who work in the laboratories of resident or visiting scientists on hands - on research projects, with each student being supervised by a senior scientist mentor. (mdibl.org)
There would be telescope operations since the typical visiting scientist would be unfamiliar with these structures. (greenbankobservatory.org)