Research activities were concentrated on three fields:

1: Observations on Mt Wilson with the Mark III optical interferometer,
   which is operated on a rotating basis by personnel based at NRL;
2: Reduction of interferometric data of binary stars and
   the determination of their orbits;
3: Reduction of astrometric data and determination of the positions of 
   stars.

ad 1: I made five trips to Mt Wilson, CA, each lasting about
      two weeks. Data taken with the Mark III instrument provides the
      basis for research in fields 2 and 3. 
ad 2: On the occasion of the end of operations on Mt Wilson with the end 
      of 1992 I re-examined the data and determined new binary orbits,
      raising the total number of binary orbits determined with the Mark 
      III to 24. About half of them have sufficient data for a 
      publication. All orbits have been updated with the available
      data, and were presented at the IAU conference on `High Angular
      Resolution Imaging', held in Sydney in January 1993. (Part of
      the results were also presented at the IAU colloquium No. 135 on
      `Complementary Approaches to Double & Multiple Star Research',
      held in Atlanta in April 1992.)
      I finished the first draft of the paper on Eta Andromedae. It 
      includes results of Monte Carlo simulations which were performed
      in order to determine uncertainties of the parameters of the 
      binary models.
ad 3: I completed the raw data reduction of all astrometry observations
      made since 1988. A first draft of the corresponding paper was
      finished. The final reduction is not yet complete. I presented
      results at the IAU conference in Sydney.
Miscellaneous: (i) I attended the conference on ``Sub-arcsecond Radio
      Astronomy'' in Manchester, held in July 1992. I gave a short talk
      on the astrometry results from the Mark III, and presented a 
      poster on my radioastronomical research while graduating in Bonn.
      The corresponding paper, which was completed last year, was
      published in Astronomy and Astrophysics (copy enclosed).
      (ii) I co-authored a paper on ``A Massive Binary Black Hole in
      the Quasar 1928+738?'', which was accepted for publication in
      the Astrophysical Journal. (A copy of the contribution with the 
      same title to the Herstmonceux Conference 1992 is enclosed).
      (iii) I gave talks on my research with the Mark III in Bonn,
      Heidelberg, and Muenchen.