This instrument uses the 60-cm SPIREX
telescope as well as a Celestron 11 inch (C-11)
mounted on top of the SPIREX tube.
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
See the page on seeing for
a brief discussion and plot.
- 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.
For more information
The group does not yet have a website.
SPIREX/HDIMM is based at the University of Chicago, Yerkes Observatory.
For more information, contact Bob Loewenstein,