We report new photometry for the cluster NGC 2121 in the Large Magellanic Cloud , which shows a prominent hydrogen core exhaustion gap at the turnoff , and a descending subgiant branch reminiscent of Galactic open clusters .
We achieve an excellent fit using the Girardi isochrones , finding an age of 3.2 \pm 0.5 Gyr , with [ Fe/H ] = -0.6 \pm 0.2 .
The isochrones fit the color and shape of the turnoff and subgiant branch so precisely that we can constrain the metallicity as well as the age .
The same isochrones also fit SL 663 and NGC 2155 , although our photometry for these clusters has much larger errors .
We find these clusters to be 0.8 Gyr younger , and 0.4 dex more metal rich , than recently reported in the literature .
Consequently , we argue that NGC 2121 , NGC 2155 , and SL 663 are not properly assigned to the age gap in the LMC , but instead are among the first clusters to have formed in the relatively metal rich , younger group of LMC clusters .
We propose a new definition of the LMC Age Gap as extending from 3.2 to 13 Gyr , with ESO121-SC03 still the only remaining candidate for membership in the age gap .