Epilogue Attainable Accuracy. Substellar and Planetary Detectability

Abstract

(a) Review. Studies of stellar paths by the technique and methods of long-focus photographic astrometry, begun shortly after the turn of the century, are being pursued with enthusiasm and intense efforts. Increased precision has been due to the dramatic increase in the speed of photographic emulsions, improved operation of older telescopes, the construction of new specially designed astrometric telescopes, and, last but not least, the introduction of high speed precision measuring machines. The results have contributed to our knowledge of motions, distances, orbital motions, masses and luminosities of stars. The past several decades moreover have witnessed a marked development in the field of perturbations in stellar paths, leading to the discovery and subsequent study of unseen companions. These have proven to be mostly bonafide stars, but also include substellar and even planet-like objects.