tweaks to SkyStats, only calculates moon phases for middle image
tweaks to SkyStats, only calculates moon phases for middle image

warnerem/pyASC,teuben/pyASC,warnerem/pyASC,warnerem/pyASC,teuben/pyASC,teuben/pyASC,teuben/pyASC,warnerem/pyASC,warnerem/pyASC,warnerem/pyASC,teuben/pyASC,teuben/pyASC,teuben/pyASC,warnerem/pyASC