SIMBAD references

We present a near-infrared (K'-band) survey of 0.7 square degree area in the α Persei open cluster (age=90Myr, distance=182pc) carried out with the Omega-Prime camera on the Calar Alto 3.5-m telescope. Combining optical data (R_c and I_c) obtained with the KPNO/MOSA detector and presented in Stauffer et al. (1999ApJ...527..219S) with the K' observations, a sample of new candidate members has been extracted from the optical-infrared colour-magnitude diagram. The location of these candidates in the colour-colour diagram suggests that two-thirds of them are actually reddened background giants. About 20 new candidate members with masses between 0.3 and 0.04M_☉ are added to the ∼400 known α Per cluster members. If they are indeed α Per members, four of the new candidates would be brown dwarfs. We discuss the advantages and drawbacks of the near-infrared survey as compared to the optical selection method. We also describe the outcome of optical spectroscopy obtained with the Twin spectrograph on the Calar Alto 3.5-m telescope for about 30 candidates, including selected members from the optical sample presented in Barrado y Navascues et al. (2002A&A...395..813B) and from our joint optical/infrared catalogue. These results argue in favour of the optical selection method for this particular cluster.