We have obtained HST-NICMOS observations of five of M31 ’ s most metal rich globular clusters : G1 , G170 , G174 , G177 & G280 .
For the two clusters farthest from the nucleus we statistically subtract the field population and estimate metallicities using K - ( J - K ) color-magnitude diagrams ( CMDs ) .
Based on the slopes of their infrared giant branches we estimate [ Fe/H ] = -1.22 \pm 0.43 for G1 and -0.15 \pm 0.37 for G280 .
We combine our infrared observations of G1 with two epochs of optical HST-WFPC2 V -band data and identify at least one LPV based on color and variability .
The location of G1 ’ s giant branch in the K - ( V - K ) CMD is very similar to that of M107 , indicating a higher metallicity than our purely infrared CMD : [ Fe/H ] \sim - 0.9 \pm 0.2 .
For the three central clusters , which are too compact for accurate cluster star measurements , we present integrated cluster magnitudes and field CMDs .

The K -band luminosity functions ( LFs ) of the upper few magnitudes of G1 and G280 , as well as for the fields surrounding all clusters , are indistinguishable from the LF measured in the bulge of our Galaxy .
This indicates that these clusters are very similar to Galactic clusters , and at least in the surrounding fields observed , there are no significant populations of young luminous stars .

For the field surrounding G280 , we estimate the metallicity to be -1.3 from the slope of the giant branch , with a spread of \sigma _ { [ Fe / H ] } \sim 0.5 from the width of the giant branch .
Based on the numbers and luminosities of the brightest giants , we conclude that only a small fraction of the stars in this field could be as young as 2 Gyr , while the majority have ages closer to 10 Gyr .