Narrow-line magneto-optical trap for erbium
  We report on the experimental realization of a robust and efficient magneto-optical trap for erbium atoms, based on a narrow cooling transition at 583nm. We observe up to $N=2 \times 10^{8}$ atoms at a temperature of about $T=15 \mu K$. This simple scheme provides better starting conditions for direct loading of dipole traps as compared to approaches based on the strong cooling transition alone, or on a combination of a strong and a narrow kHz transition. Our results on Er point to a general, simple and efficient approach to laser cool samples of other lanthanide atoms (Ho, Dy, and Tm) for the production of quantum-degenerate samples. 
A. Frisch, K. Aikawa, M. Mark, A. Rietzler, J. Schindler, E. Zupanic,   R. Grimm, F. Ferlaino
physics.atom-ph cond-mat.quant-gas