Question:
Who was the chair of Paris Observatory, PSL University in Mar, 1998?

Context:
 Claude Catala is the chair of Paris Observatory, PSL University from Jan, 2011 to Mar, 2020. 
 Giovanni Domenico Cassini is the chair of Paris Observatory, PSL University from Jan, 1671 to Jan, 1712. 
 Michel Combes is the chair of Paris Observatory, PSL University from Jan, 1991 to Jan, 1999. 
 Jacques Cassini is the chair of Paris Observatory, PSL University from Jan, 1712 to Jan, 1756. 
 César-François Cassini de Thury is the chair of Paris Observatory, PSL University from Jan, 1756 to Jan, 1784. 
 Daniel Egret is the chair of Paris Observatory, PSL University from Jan, 2003 to Jan, 2011. 
 Fabienne Casoli is the chair of Paris Observatory, PSL University from Mar, 2020 to Dec, 2022. 
 Dominique, comte de Cassini is the chair of Paris Observatory, PSL University from Jan, 1784 to Jan, 1845.

Answer:
Michel Combes