more mixture components for color priors

[jeff-regier]

According to spectrographs, the objects at

• 5.1439, 0.0885
• 5.5156, 0.1048
• 5.7299, 0.0265, and
• 5.5853, 0.1438

are red dwarfs in our collection of stamps that Celeste incorrectly labels galaxies. Presumably our current color prior---a 2 component mixture model---doesn't have enough components to adequately model stars outside of the main sequence (e.g. red dwarfs).

http://skyserver.sdss.org/dr12/en/get/SpecById.ashx?id=1258871587503892480
http://skyserver.sdss.org/dr12/en/get/SpecById.ashx?id=1261149226344146944
http://skyserver.sdss.org/dr12/en/get/SpecById.ashx?id=1261148676588333056
http://skyserver.sdss.org/dr12/en/get/SpecById.ashx?id=1258898800416679936