In the first month of the third quarter of 1993 I completed the data 
reduction of Capella and finished the first draft of the corresponding 
paper. I worked together with Robert Wilson (University of Florida), who 
was visiting us for eight weeks, to incorporate his light curve program 
for interacting binaries into our binary analysis software. This allows 
us to study the effects of star spots, limb darkening, rotation and 
gravity darkening on our visibility measurements. As I have mentioned in 
my last report, there is the possibility that effects due to star spots 
on the hotter component of Capella can be seen in our data. I also 
obtained stellar evolution data and a program to calculate isochrones 
from the University of Geneva in order to help discuss the evolutionary 
state of our binaries. 

In August, I started to teach myself the programming language C, because 
it will be the official language for the data reduction software of the 
new interferometer in Arizona. I took a vacation during the second half of 
August. 

In September, I continued my C studies. I also became involved in the 
investigation of special algorithms which we will need for the global 
reduction of several years of data from the Astrometric Interferometer, 
in order to obtain stellar positions, parallaxes and proper motions. The 
design matrix of the corresponding set of linear equations will be very 
large, but very sparse. I implemented a sparse matrix solution program, 
which we obtained from Norbert Zacharias at the USNO and which is used 
for the global block adjustment in opical astrometry, into the Mark III 
astrometry software and tested it. I also wrote a completely new version 
of this program to perform a Cholesky decomposition of sparse matrices, 
which turned out to be much faster than the other version and also less 
demanding on disk space for the storage of the matrices. 

At the end of the quarter, I submitted the Astrometry paper to the 
Astronomical Journal (AJ). I also received word that the Eta Andromedae 
paper, which I had submitted in the second quarter of 1993, had been 
accepted for publication in the AJ.