U.S. Naval Observatory's Programs to Determine Accurate Proper Motions of Faint Stars

Previous abstract Next abstract

Session 17 -- Instrumentation, Techniques and Surveys
Oral presentation, Monday, June 12, 1995, 2:00pm - 3:30pm

[17.06] U.S. Naval Observatory's Programs to Determine Accurate Proper Motions of Faint Stars

S. E. Urban (USNO)

Currently, global, proper motion catalogs are limited to stars brighter than visual magnitude 10.5. In order to increase our knowledge of galactic kinematics as well as extend the optical reference frame, proper motions of fainter stars are required. A number of projects are underway at the USNO that will result in accurate positions and proper motions for stars of much fainter magnitudes. These projects include: new reductions of Astrographic Catalogue (AC) data (average epoch about 1905); measurement and reductions of the USNO's twin astrograph plates taken in the early 1980's; re-measurement and reduction of the Palomar Sky Survey plates; and a new program to accurately determine positions of all stars 14th magnitude and brighter using the USNO's 8" astrograph with improved optics. When combined, the results of these programs will give astrometric data for millions of stars whose current positions and proper motions are undetermined.

A cornerstone for proper motion determinations is the data contained in the Astrographic Catalogue. The data's early epoch (about 1905), global coverage and positional accuracy make them the best source of first epoch positions for stars down to 13th magnitude. Each of the 22 AC zones is being reduced independently, with corrections being applied when needed for plate tilt, radial distortion, coma, magnitude equations and other field distortions. It is expected that the reductions of the entire AC, containing about five million stars, will be completed by the end of 1996.

Monday program listing