NOAO >   Observing Info >   Approved Programs >   2007A-0454

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Proposal Information for 2007A-0454


PI: Hugh C. Harris, US Naval Observatory, hch@nofs.navy.mil
Address: 10391 W. Naval Observatory Rd., Flagstaff, AZ 86001, USA

CoI: Arne Henden, AAVSO
CoI: Conard Dahn, US Naval Observatory
CoI: Jeffrey Pier, US Naval Observatory

Title: Spectra to Support Accurate Parallaxes

Abstract: Trigonometric parallaxes with increasing precision allow us to measure distances to rare objects such as planetary nebulae with distances of hundreds of parsecs. The long-standing uncertain distance scale of PNe is being addressed with these parallaxes -- now 16 PNe have significant parallaxes, although most are small (only a few mas). To turn high precision into high accuracy, the distances of reference stars must be determined with spectrophotometry. Photometry has already been obtained, but spectra are needed to resolve ambiguities by making spectroscopic temperature and luminosity classifications using strengths of established spectral features. We propose to use Hydra to acquire spectra of reference stars around 9 PNe, 4 Cataclysmic Variables, and 2 other peculiar variables. These objects all have small parallaxes and have reference stars that need better accuracy to match the parallax precision and improve the accuracy of the final distance determinations.


National Optical Astronomy Observatory, 950 North Cherry Avenue, P.O. Box 26732, Tucson, Arizona 85726, Phone: (520) 318-8000, Fax: (520) 318-8360



NOAO >   Observing Info >   Approved Programs >   2007A-0454

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