UNIVERSITIES SPACE RESEARCH ASSOCIATION



Employee Name: Christian A. Hummel

USRA Division and Program: Space Astronomy, Astronomy & Astrophysics

Government Site: US Naval Observatory

Government Sponsor: D. Mozurkewich (NRL), K. Johnston (USNO)



EMPLOYEE SUMMARY OF ACCOMPLISHMENTS

General Description of your Research Activities: 

A major part of my work since the last annual report concerned the
data reduction software for the Navy Prototype Optical Interferometer
(NPOI). In particular, I am responsible for a program called CHAMELEON,
which does the data averaging and calibration. The program is mostly
finished and is awaiting data from NPOI for its completion. The code 
consists of more than 10000 lines in IDL scripts and about 2000 lines
of C. I tested parts of CHAMELEON with Mark III data, which was re-
formatted for this purpose. 

In order to facilitate access to existing star catalogs and retrieve
information, I wrote STARBASE. With it, the user can access various
catalogs (e.g. the Hipparcos Input Catalog, the Bright Star Catalogue,
etc.), and compile a list of information on selected stars. STARBASE 
also calculates stellar astrophysical parameters and estimates binary
star separations for selection of observing lists for the binary program
of the NPOI. STARBASE might also become a scheduling aid for the NPOI.

In Fall of 1994, David Buscher left the group and I took over the task
of finishing his contribution to the NPOI data reduction software,
CONSTRICTOR. This was, however, delayed by the lack of real data from
the interferometer.

I began to write another data reduction program, PICTOR, which will
be used for modeling stellar disks and binaries.

In scientific matters, I completed a paper on "Orbits of small angular
scale binaries resolved with the Mark III interferometer". It was sub-
mitted to the Astronomical Journal, and is scheduled to appear in the
July 1995 issue. The paper presents the orbits of eight binaries, as
well as the determination of astrophysical quantities like masses and
absolute luminosities for the binary components. (Results of this work
were presented at the IAU Symposium 166 in The Hague, August 1994).

I am participating in a collaboration with colleagues of the Joint
Institute for Laboratory Astrophysics in Boulder, CO, on the eclipsing
binary star Zeta Aurigae. Our contribution to spectroscopic measurements
are orbital elements and the diameter of the K4 supergiant component
from observations with the Mark III interferometer. (A paper is in 
preparation.) We have also agreed on continuing this collaboration
into the NPOI operations for observations including Zeta Aurigae systems.
Along the same lines, I have joined Deane Peterson (Stonybrook College,
NY) in writing a proposal to the Kitt Peak McMath Telescope to observe
some of the binaries of the Mark III list in order to resolve problems
with previous spectroscopy.

I have resumed some radioastronomical work on quasars in collaboration
with a group at the Max-Planck Institute for Radioastronomy in Bonn,
Germany. For the purpose of this, I installed AIPS and DIFMAP (a mapping
package for interferometric data from Caltech) on our workstation. In
particular, I work on QSO 0153+744, a source for which we have obtained
sufficient data for a detailed investigation and subsequent publication. 

Towards the end of the report period, I have agreed to help out with
observations of binary stars with the 26-inch refractor here at the
Naval Observatory. This involves operations of the telescope itself,
and of the speckle interferometry camera attached to it. The USNO is
one of the very few observatory left who regularly observe binaries.
It also maintains the Washington Double Star Catalog (WDS).




Honors or Awards Received: None


Papers Published or Accepted for Publication: (include complete
bibliographic citations)

Hummel, C.A., Mozurkewich, D., Elias II, N.M., Quirrenbach, A., 
        Buscher, D.F., Armstrong, J.T., Johnston, K.J., Simon, R.S., 
        Hutter, D., 1994, AJ 108, 326
        "Four years of astrometric measurements with the Mark III 
         optical interferometer"

Quirrenbach, A., Mozurkewich, D., Buscher, D.F., Hummel, C.A.,
        Armstrong, J.T., 1994, A&A 286, 1019  
        "Phase-referenced visibility averaging in optical long-baseline
         interferometry"

Buscher, D.F., Armstrong, J.T., Hummel, C.A., Quirrenbach, A., 
        Mozurkewich, D., Johnston, K.J., Denison, C.S.,
        Colavita, M.M., Shao, M., 1995, Applied Optics, 34, 1081
        "Interferometric seeing measurements on Mt. Wilson -
         power spectra and outer scales"

Hummel, C.A., Armstrong, J.T., Buscher, D.F., Mozurkewich, D., 
        Quirrenbach, A., Vivekanand, M., 1995, AJ (in press)
        "Orbits of small angular scale binaries resolved with the Mark 
         III interferometer"




Papers Submitted but not yet accepted for Publication: (include full citation)

None


Papers Presented at Scientific Meetings:
Invited Papers: (include title or talk, meeting name, date)

C.A. Hummel, October 1994, NPOI Dedication, Flagstaff, AZ
"Results from the Mark III Interferometer on Mt. Wilson"


Contributed Papers: (include title, meeting, and date)

C.A. Hummel, August 1994, IAU Symposium 166, The Hague, The Netherlands
"Single and Double Star Astrometry with the Mark III Interferometer"

P.D. Bennett, G.M. Harper, A. Brown, C.A. Hummel, January 1995, AAS, Tucson, AZ
"A Re-analysis of the Zeta Aurigae Binary System" 



Colloquia, Seminars, and Special Lectures:  (include a listing of scientific
meetings attended)

"The Analysis of Emission Lines", May 1994, STScI, Baltimore, MD
"Washington Area Astronomers meeting", March 1995, STScI, Baltimore, MD
"Quasars and AGN: High Resolution Radio Imaging", March 1995, Irvine, CA


Community Service: (e.g. Offices in professional societies, lectures to
community or educational groups, consultation, etc.)



University Collaborations: (include course taught, collaborative research
projects undertaken, visits taken, students mentored, etc.)



Other Collaborative Activities: (describe significant collaboration with or
contributions to other (non-university) research groups - anywhere in the world)
Membership in Professional Societies and Organizations:

Member of Commission 26 (Double stars) of the IAU.
Member of the American Astronomical Society


Additional Information:  (include any information you feel useful in
evaluating your performance)





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