At his word the stars were fixed, and he knows the number of the stars: Compare Psa 147.4; Isa 40.26. The verb fixed may be expanded to “fixed in their places” (New English Bible). Good News Bible provides a good model for this verse, and so does Contemporary English Version, which says:

• With one word he put the stars in place, and he knows exactly how many there are.

Quoted with permission from Bullard, Roger A. and Hatton, Howard A. A Handbook on 1-2 Esdras. (UBS Helps for Translators). Miami: UBS, 2019. For this and other handbooks for translators see here.