John R. Thorstensen

Academic Appointments
  • Professor of Physics and Astronomy

  • President, MDM Observatory Corporation

John Thorstensen is an optical observational astronomer. He has been at Dartmouth since 1980. His undergraduate degree was from Haverford College (1974), which was followed by graduate studies in the Berkeley (California) Astronomy Department. He specializes in observations of cataclysmic binary stars. Since 2007 he has served as the director of the MDM Observatory on Kitt Peak, Arizona; MDM is operated by a consortium of five universities. Thorstensen developed the program JSkyCalc and its antecedents, which are widely used in planning observations.

+ View more


Wilder, Room 239
HB 6127


  • B.A. Haverford College
  • Ph.D. University of California at Berkeley

Selected Publications

  • Thorstensen, J. R., 2020, "Follow-up Studies of Five Cataclysmic Variable Candidates Discovered by LAMOST". Astronomical Journal, 160, 151; available at arXiv : 2007.09285

  • Thorstensen, J. R., 2020, "Spectroscopic Studies of 30 Short-period Cataclysmic Variable Stars, and Remarks on the Evolution and Population of Similar Objects". Astronomical Journal, 160, 6; available at arXiv: 2005.02150

  • Thorstensen, J. R. Ringwald, F. A.,  Taylor, C. J., Sheets, H. A., Peters, C. S., Skinner, J. N., Alper, E. H., and Weil, K. E. 2017, "New or Improved Orbital Periods of Cataclysmic Binaries", 2017, Research Notes of the AAS, 1, 29.  Available at

  • Thorstensen, J. R., Alper, E. H., and Weil, K. E. 2016,  "A Trip to the Cataclysmic Binary Zoo: Detailed Follow-Up of 35 Recently-Discovered Systems'',  The Astronomical Journal, 152, 226.  Preprint version at arXiv:1609.02215

+ View more

Works In Progress

  • I maintain a large, merged catalog of cataclysmic variables that I update with CV candidates from ASASSN, ZTF, ATLAS, Gaia-alerts, and other sources such as the AAVSO VSX listing.   This is used to select targets for characterization, especially orbital period determination, at MDM Observatory.  While most objects prove to be variations on a theme, so to speak, some very interesting objects (such as LAMOST 0240+19; see the publications list) appear from time to time.

  • I have many observations of cataclysmic binaries, most importantly orbital periods, that have not yet been published in detail; the RNAAS reference in the publications list includes many, but not all of these, and new results accumulate almost continuously.  Queries from interested observers are encouraged. 

  • A ground-based parallax program has been abandoned because the Gaia results have rendered these efforts obsolete.  A retrospective assessment of the accuracy of the results can be found in Bradley Schaefer's article on nova distances (arXiv link).