Summary

CARA implemented a differential image motion monitor, as described by Sarazin and Roddier (1990), but modified the design by eliminating the prism, adding a Hartmann aperture mask, and defocusing the telescope to image each sub-aperture of the mask. We call this arrangement a Hartmann differential motion monitor (H-DIMM), and described the technique in Bally et al. (1996). With a mask of n apertures, the number of baselines is given as n*(n-1)/2, permitting a highly redundant calculation of the seeing.

Results

• Sarazin, M., and Roddier, F. 1990, "The ESO Differential Image Motion Monitor," A&A, 227, 294.
• Bally, J., Theil, D., Billawala, Y., Potter, D., Loewenstein, R. F., Mrozek, F., and Lloyd, J. P, 1996, "A Hartmann Differential Image Motion Monitor (H-DIMM) for Atmospheric Turbulence Characterisation," Publ. Astron. Soc. Australia, 13, 22.
• Loewenstein, R. F., Bero, C., Lloyd, J. P., Mrozek, F., Bally, J., and Theil, D. 1998, "Astronomical Seeing at the South Pole," in Astrophysics from Antarctica (ASP Conf. Proc. 141), ed. G. Novak and R. H. Landsberg, p. 296.

Pictures

For more information

SPIREX/HDIMM is based at the University of Chicago, Yerkes Observatory. For more information, contact Bob Loewenstein, rfl@oddjob.uchicago.edu .

CARA's research and education programs are supported in part by the National Science Foundation under a cooperative agreement, grant number NSF OPP 89-20223. © Copyright 1998,1999,2000 by Center for Astrophysical Research in Antarctica. This copyright applies to all web pages and images created by CARA.