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Session 77 - Binary Stars.
Display session, Wednesday, January 15
Metropolitan Ballroom,

[77.18] On the Road to Determining the White Dwarf Luminosity Function: A Comparison of Two Photometric Reduction Methods

R. S. French (M.T.S.U.), T. D. Oswalt (Fla.Tech)

We present BVRI photometry of several wide binaries which contain white dwarf (WD) components. In a test for random and systematic effects in reductions of the co-added CCD data, we compare two independent ways of correcting for atmospheric extinction and for transforming to the standard photometric systems. The first is an interactive method that isolates the determination of the individual photometric variables. The second method uses routines included in the IRAF software provided by NOAO. We show that the two methods give essentially identical results, within the uncertainties determined for each variable.

The BVRI data reported here will contribute to our determination of the WD luminosity function, from which we hope to derive a firm lower limit on the age of the Galactic disk (see the paper by Smith amp; Oswalt elsewhere at this meeting, and Oswalt et al. 1996 Nature 382, 692). Our photometric parallaxes will also be used to examine the distribution of projected semimajor axes among wide binaries.

This project was supported in part by the SARA Research Experiences for Undergraduates Summer Internship Program (NSF AST 94-23922). RSF was a visiting observer at the SARA Observatory at Kitt Peak, which is operated by the Southeastern Association for Research in Astronomy. TDO gratefully acknowledges support from NSF grant AST 90-16284 and the Dudley Observatory.

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