Atheism and objective ethics

[DeistPaladin]

Can atheists argue for an objective ethics?

I still want someone to define "objective morals" or "objective ethics" for me.

Last I checked, "objective" means it's measurable in a way not subject to opinion, as in what can be determined in a science lab. Mass, temperature and velocity are all mathematically and therefore objectively measurable. Do those who argue for "objective ethics" mean to imply we can establish units of measure for right and wrong? Can we plug these numbers into a spreadsheet and determine the right course of action?

OK, that aside, I don't see how acknowledging subjective morality concedes anything to the theist. Does the theist think that God makes morality any less subjective?

If GodWillIt* because it's good, then morality exists outside of God and good would still be good without God.

If things are good because GodWillsIt, then this is not objective morality by definition. This is a being, however wise or powerful, who makes up rules.

Theists try to create an escape clause by claiming that "goodness is part of God's nature" (whatever the fuck that means) which leads to circular thinking like "God is good because God is good". I also wonder if this fits the definition of begging the question, inventing a definition of God and then using it to "prove" that one can't be moral without God ("We define God as good, you don't believe in God so therefore you can't be good").

* GodWillsIt = my moral philosophy version of GodDidIt.