RAVE DR5 Neighbourhood

Table <code>ravedr5_neighbourhood</code> includes all good neighbours for each matched RAVE DR5 object. A good neighbour for a given RAVE DR5 source is a nearby Gaia object whose position is compatible (within position errors) with the RAVE DR5 target. The cross-match algorithm is not symmetric and searches RAVE DR5 sources counterparts in Gaia. The cross-match algorithm is positional and exploits the full 5 parameter covariance matrix of the Gaia astrometric solution when available and the external catalogue positions and position errors. In addition it takes into account the Gaia environment using the local density.
Please note that the cross-match algorithm is a trade-off between multiple requirements, in particular between completeness and correctness. It is thus not limited to a simple cone search.
Reference papers:Marrese et al. (2017)Marrese et al. (2019)

表<code>ravedr5_neighbourhood</code>收录了每个匹配RAVE DR5天体的全部优质邻源。对于指定的RAVE DR5源而言，优质邻源指的是位置与该RAVE DR5目标天体的位置误差范围内兼容的近距Gaia（盖亚）天体。该交叉匹配算法不具备对称性，仅在Gaia（盖亚）星表中检索RAVE DR5源的对应天体。此算法为位置型匹配算法，在可用时会利用Gaia天体测量解的全五参数协方差矩阵，并结合外部星表的位置与位置误差信息；此外，还通过局部密度参数考量Gaia星表的局部环境特征。

需注意，该交叉匹配算法是多项需求之间的权衡结果，尤其体现在完备性与正确性之间的平衡，因此其并不局限于简单的圆锥搜索。

参考文献：Marrese等人（2017）、Marrese等人（2019）