1 INTRODUCTION
2 OBSERVATIONS AND DATA REDUCTION
2.1 Target selection and observations
2.2 Data reduction
3 RESULTS
3.1 Spectral type and effective temperature
3.2 Comparison of near-infrared spectral types to AstraLux optical photometry
3.3 Comparison with integrated optical spectral types
3.4 Surface gravity and chromospheric activity
4 DISCUSSION
4.1 Additional youth indicators
4.2 Hertzsprung-Russell diagram
5 SUMMARY AND CONCLUSIONS