Hi General and Rick, Juan states there that Ideally, A should not be larger than 0.3 or 0.5. The tool documentation states the bottom line "Use only moderately bright, average stars, and avoid saturated stars, too bright and too dim stars." Generally, that's in the 0.3-0.8 range for a lot of data I work with. Rick, if what you see is .04-.02, then obviously use what you have. Our respective imaging scales aren't necessarily a function of the amplitude/brightness of our stars.