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G. Gatewood (University of Pittsburgh)
To extend our bright star parallax program to below the magnitude cutoff of the HIPPARCOS catalog, we have installed a CCD tail piece on the red-light correct 0.76-m Thaw refractor. The 2048 x 2048 back-side-illuminated Marconi chip has a scale of 0.196 arc sec per pixel on the f18.7 refractor. Initial estimates of the precision of the system as a function of stellar magnitude have been obtained from the standard error of the positions of stars observed for four hours, the approximate observing time given to a parallax target star. As illustrated by the HIPPARCOS catalog, a parallax study extending over approximately 3 years has similar positional and parallax standard errors. Our tests indicate that the standard error is between approximately 0.6 and 1 mas down to stars as faint as the 16th magnitude. The results are better illustrated under research on our website, (www.pitt.edu slash tilda aobsvtry). Initial results include the correction of a 200 mas Hipparcos parallax error and a preliminary parallax for Teegarden's star.
Most of the program stars are either suspected late M dwarfs, or cool white dwarfs apparently within 20 parsecs of the Sun. U, B, V, R, and I, photometry of the target and reference stars is obtained with a secondary telescope and CCD camera attached to the refractor. Correction to absolute will be enhanced by the use of relatively faint reference stars for which we will have approximate temperatures and magnitudes. Bright stars are observed through central ND filters of 2.5, 5.0, 7.5, and 10.0 magnitudes. A similar precision is obtained for ND filtered and non-ND filtered stars. This research and instrumentation was made possible by National Science Foundation grants 0098552 and 013822.
If you would like more information about this abstract, please follow the link to http://www.pitt.edu/~aobsvtry/. This link was provided by the author. When you follow it, you will leave the Web site for this meeting; to return, you should use the Back comand on your browser.
The author(s) of this abstract have provided an email address for comments about the abstract: gatewood@pitt.edu
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Bulletin of the American Astronomical Society, 36 #2
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