Purpose:

Dr. Markus Wittkowski has worked with the NPOI group since the beginning of 
this year (2000). The purpose of this 1-year visit is the search for structures 
on the surfaces of late-type giant and supergiant stars using new data from
the Navy Prototype Optical Interferometer (NPOI).

Programmatic research:

Due to technical difficulties, it has not been possible so far to obtain new 
data with NPOI for the objects selected by Dr. Wittkowski for his studies. He
has therefore concentrated his research on existing data as well as 
simulations in preparation of future observations. His work was in the
following areas:

	Reduction and analysis of observations of Nu Virginis.

	Feasibility studies of diameter and limb-darkening determinations
	given the existing configurations of the NPOI.

Publications:

No publications based solely on work done so far during his visit have been 
prepared. It is anticipated that the quality of the work warrants a publication,
somewhat depending on obtaining new observations with NPOI specifically 
tailored for limb-darkening studies.

Performance appraisal:

Dr. Wittkowski's thorough analysis of existing observations has shown that he 
pays great attention to details affecting the results of his studies. He has
adopted the available reduction tools for interferometric data, while at the
same time developing software of his own to address specific questions of
stellar parameter determinations. 

Dr. Wittkowski contributed useful insights as to the analysis and modeling
of interferometric data, which are also valuable in the context of data
verification and numerical modeling. He has presented results to the NPOI
group and plans to communicate his research at the upcoming meeting of the 
AAS in Rochester.


Date of review: May 9, 2000
Reviewed by: Dr. C. A. Hummel