Another green smudge associated with H-Alpha feature

http://legacysurvey.org/viewer?ra=14.9689&dec=15.7381&zoom=11&layer=sdss2

The H-alpha line (646 nm) lies in the middle of the r-band filter, which is green in these images (zrg = RGB).

Aha. Check out the latest image - that one’s blue! :upside_down_face: