Consider allowing VAR=1 stars with a large mag_err for acquisition

[taldcroft]

Canonical example: 18925 in which the flight catalog included a 9.5 mag star 41553480 but proseco ignores it because it has VAR=1 (suspected variability < 2 mag). Not clear if that is a justifiable choice but it was indeed acquired at 9.375 mag.

So maybe allow these in the candidate list but bump mag_err to something large like 1.5?