The Thaw Refractor with the Multichannel Astrometric Photometer (MAP) Attached
The Thaw is a 30-inch refracting telescope; the third largest of its kind in the world. It has a focal length of over 561 inches, making it approximately f/19. In 1989 the original photographic lens was replaced - solely by private funds collected and donated by the
Extrasolar Planetary Foundation
with a lens corrected for the red. This improvement was made because the skies are fairly dark at red wavelengths, thereby reducing the effects of light pollution. At the tail end of the telescope (bottom left in photo) the MAP instrument is visible.

The Multichannel Astrometric Photometer (MAP) is a device to be used for the measurement of stellar image positions in the telescope's focal plane.

A survey of 20 nearby stars to detect the nonlinear variations in their motion produced by planetary systems is continuing. The MAP acheives a precision of about 3.4 milliarcseconds per observation. Since it makes 3 observations per night (of each region) it equates to the Thaw/MAP precision as being 2.0 milliarcseconds per night.

The anual precision is somewhat in the same ball park. The program acheives at least 16 observations into the mean of each planet target per year. Thus, 3.4 divided by the square root of 16 is very close to 1.0 milliarcsecond per year.

Primary MAP Catalog Stars
MAP Target Stars


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