Variable stars in the Tycho photometric observations

I. Detection

¹ Observatoire astronomique de Strasbourg, 11 rue de l'Université, 67000 Strasbourg, France
² Copenhagen University Observatory, Juliane Maries Vej 30, 2100 Copenhagen Ø, Denmark
³ Institute for Astrophysics, Technikerstrasse 25, 6020, Innsbruck, Austria
⁴ Observatoire astronomique de Bordeaux, 33270 Floirac, France
⁵ ESO, Karl-Schwarzschild-Strasse 2, 85748, Garching, Germany

Corresponding author: S. Piquard, piquard@astro.u-strasbg.fr

Received: 11 September 2000
Accepted: 24 April 2001

Abstract

We present an original way to detect variable stars in the Tycho photometric observations. A modified Kolmogorov-Smirnov statistical test has been constructed, based on a model of most of the satellite's parameters, leading to the dispersion in the measurements. This allows us to build a treatment taking into account truncated detections and censored measurements, and to search for variability in the faint part of the catalogue. The selection threshold of variable stars has been calibrated to minimize false alarm rate. Reliable results were thus obtained for stars as faint as 11 mag. One thousand and ninety-one suspected variable stars have been listed, 407 of which are already known in Hipparcos, GCVS or NSV, and 684 of which are suspected variable stars to be identified soon.