I've been skimming through Beekes' book again (Comparative
Indo-European Linguistics). On p. 39, he flat out states: "there is only one
name of an Indo-European god which we know".
This is Day-Sky-Father, Zeus, etc, of course. He
dismisses a relationship between Varuna-Ouranos as untenable.
His statement, however, is contradicted by others. We do know
the name of Dawn: EIEC gives as *Haeusos. Something in the
way of a name is also reconstructed for Moist Mother Earth.
Beekes does have his idiosyncracies. He also flatly states
that PIE lacked [a]. I think we are expected to humor the great
man.
Mark.