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.

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Some selected publications are listed below.  The query form of the Astrophysics Data System will produce a comprehensive, up-to-date list.

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239 Wilder
HB 6127
Physics and Astronomy
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

Halpern, J. P., and Thorstensen, J. R. 2015, "Optical Studies of Thirteen Hard X-ray Selected Cataclysmic Binaries",  Astronomical Journal, 150, 170. Available at arXiv:1510.00703

Skinner, J. N., Thorstensen, J. R., and Lepine, S. 2014, "Cataclysmic Variables in the SUPERBLINK Proper Motion Survey", Astronomical Journal, 148, 115.  Available at arXiv:1409.1921

Thorstensen, J R,, and J N Skinner, 2012, "Spectroscopy and Photometry of Cataclysmic Variable Candidates from the Catalina Real Time Survey, Astronomical Journal, 144, 81   Available at arXiv:1207:3070

Thorstensen, J R., Peters, C. S.,  and Skinner, J. N., 2010, "Optical Studies of 20 Longer-Period Cataclysmic Binaries" , Publications of the Astronomical Society of the Pacific, 122, 1285 Available at arXiv:1009:1265

Thorstensen, J R, S Lepine, M Shara, 2008, "Parallax and Distance Estimates for Twelve Cataclysmic Variable Stars", Astronomical Journal, 136, 2107.  Available at arXiv:0809:1550

Thorstensen, J R and E Armstrong, 2005, “Is FIRST J102347.6+003841 Really a Cataclysmic Binary?” Astronomical Journal , 130, 759.   Available at astro-ph/0504523

Thorstensen, J R, W H Fenton, J O Patterson, J Kemp, T Krajci, and I Baraffe, 2002,  “1RXS J232953.9+062814: A Dwarf Nova with a 64-minute Orbital Period and a Conspicuous Secondary Star,” Astrophysical Journal Letters , 567, L49.   Available at astro-p/0201487

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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).