An evaluation of the membership probability of 212 $\lambda$ Boo stars: I. A Catalogue

The literature on the $\lambda$ Boo stars has grown to become somewhat heterogenous, as different authors have applied different criteria across the UV, optical and infrared regions to determine the membership status of $\lambda$ Boo candidates. We aim to clear up the confusion by consulting the literature on 212 objects that have been considered as $\lambda$ Boo candidates, and subsequently evaluating the evidence in favour of their admission to the $\lambda$ Boo class. We obtained new spectra of $\sim$90 of these candidates and classified them on the MK system to aid in the membership evaluations. The re-evaluation of the 212 objects resulted in 64 members and 103 non-members of the $\lambda$ Boo class, with a further 45 stars for which membership status is unclear. We suggest observations for each of the stars in the latter category that will allow them to be confidently included or rejected from the class. Our reclassification facilitates homogenous analysis on group members, and represents the largest collection of confirmed $\lambda$ Boo stars known.