Welcome to H-Turk, a member of H-Net Humanities & Social Sciences Online. H-Turk is the H-Net/TSA network for Ottoman and Turkish studies.
Dear Irvin Hocam
I hope not being so late. I can help you with this if you don't mind.
My contact address is firstname.lastname@example.org
All the best.
This sounds as though this would have been the Imperial ambassador, i.e. the representative of the Holy Roman Emperor (in other words, the Austrian Habsburg ambassador). In Latin, the Emperor was referred to as Caesar so the term you used would have been derived from this. Imperial ambassador would be the more common way of referring to these people in English nowadays. Does your term come from a Latin or Italian source?
The best (if probably somewhat outdated and inaccurate) list of individuals who held this office in the seventeenth century is contained in
Dear colleages, I would like to announce the publication of my book Waiting for Müteferrika: Glimpses of Ottoman Print Culture (Boston: Academic Studies Press, 2018), xxiv+143 pages, 3 illustrations including.
Global Environmental Borderlands in the Age of Empire: A Joint Symposium in 2019-2020 Sponsored by the William P. Clements Center for Southwest Studies at Southern Methodist University and the Center for Spatial and Textual Analysis at Stanford University
The Clements Center for Southwest Studies at Southern Methodist University in Dallas and the Center for Spatial and Textual Analysis at Stanford University in Palo Alto solicit proposals for papers that explore the environmental history of borderlands in the early modern world.