A color-magnitude (CM) filter used to suppress the noise from foreground stars while preserving the signal from dwarf galaxy stars at a specific distance. (a) and (c) CM filters for an old and metal-poor stellar population at a distance modulus of 16.5 and 20.0, respectively. The solid lines show Girardi isochrones for 8 and 14 Gyr populations with and . (b) and (d) These CM filters overplotted on stars from a 1 field to illustrate the character of the foreground contamination as a function of dwarf distance. Data are from SDSS DR7.
