Astron. Astrophys. Suppl. Ser. 130, 477-484

Stellar $uvby\beta$ photometry in three EUV shadow directions

J. Knude

Niels Bohr Institute for Astronomy, Geophysics and Physics, Juliane Maries Vej 32, DK-2100 København Ø, Denmark
e-mail: indus@astro.ku.dk

Received November 18, 1997; accepted January 19, 1998

Abstract:

We present the $uvby\beta$ data used to locate the dust and derive distances for nearby diffuse interstellar clouds in the EUV shadows lb27-31, lb165-32 and lb329+46 discovered by the Extreme Ultraviolet Explorer.
The photometrically derived parallaxes of our program stars are compared to the parallaxes listed in the Hipparcos Catalog. Within the photometric distance limit of 150 pc, the photometric parallaxes of 21 "normal" stars are consistent with the Hipparcos measurements within an uncertainty of 15$\%$.Much as expected for the Strömgren system. Since all program stars are brighter than $V\approx$11.5 most of them are included in the Tycho photometry. For our sample of $\sim$200 stars we find $V\rm _{by}$ and $V\rm _T$ to be consistent. Few stars are common to published $uvby\beta$ catalogs, $\sim$10, V and the indices compare well apart from $\beta$ where a zero point difference of 11 mmag is noticed.

Key words: stars: distances -- solar neighbourhood -- ISM: clouds