We present WFPC2 and ground-based VI photometry of NGC 121 and a nearby field in the outer SMC .
For NGC 121 , we measure a true distance modulus of \mu _ { 0 } = 18.96 \pm 0.04 ( distance of 61.9 \pm 1.1 kpc ) , age of 10.6 \pm 0.5 Gyr , metallicity of [ \hbox { Fe / H } ] = -1.03 \pm 0.06 , and initial mass of 4.1 \pm 0.4 \times 10 ^ { 5 } M _ { \odot } , assuming a Salpeter IMF with lower cutoff at 0.1 M _ { \odot } .
In the outer SMC field , we find evidence of stars covering a wide range of ages – from 2 Gyr old to at least 9 - 12 Gyr old .
We have measured the distance , extinction , and star formation history ( past star formation rates and enrichment history ) using a CMD-fitting algorithm .
The distance modulus of the SMC is measured to be \mu _ { 0 } = 18.88 \pm 0.08 , corresponding to a distance of 59.7 \pm 2.2 kpc .
The overall star formation rate appears to have been relatively constant over this period , although there may be small gaps in the star forming activity too small to be resolved .
The lack of current star-forming activity is a selection effect , as the field was intentionally chosen to avoid recent activity .
The mean metallicity of this field has increased from an average of [ \hbox { Fe / H } ] = -1.3 \pm 0.3 for stars older than 8 Gyr to [ \hbox { Fe / H } ] = -0.7 \pm 0.2 in the past 3 Gyr .