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Astron. Astrophys. 361, L49-L52 (2000)

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2. Observations

Spectroscopic and photometric monitoring campaigns have been conducted at different sites and using different telescopes over the past two observing seasons October 1998-March 1999 and October 1999-March 2000.

Photometry - The photometric observations reported here have been carried out in the Johnson B and V bands with the 91-cm Cassegrain telescope at the M. G. Fracastoro station (Serra La Nave, on Mt. Etna) of the Catania Astrophysical Observatory, using a photon-counting cooled photometer equipped with an EMI 9893QA/350 photomultiplier. Field stars of known magnitudes and colour indices from Landolt's selected areas (1992) have been observed to transform the instrumental magnitudes to the Johnson photometric system.

Spectroscopy - High-resolution spectra were obtained between August 1998 and December 1999 at the Calar Alto observatory with FOCES at the 2.2 m telescope, and at ESO/La Silla observatory with CORALIE at the Swiss 1.2 m telescope. Details on the reduction and analysis of FOCES data are given by Alcalá et al. (2000).

Radial velocities have been determined by cross-correlating the observed spectrum with a template. Standard star spectra, and a numerical binary mask of CORAVEL-type (Barrane et al. 1979) have been used as templates for the observations obtained with FOCES and with CORALIE, respectively. In all cases, the error on the radial velocity measurements is less than 1 km s-1. A third, fainter, close visual component (Alcalá et al. 2000) is also seen spectroscopically at a radial velocity of [FORMULA] km s-1, which is about the same as the systemic radial velocity of the spectroscopic binary.

Near-infrared imaging - Additionally, adaptive optics observations of RXJ 0529.4+0041 in the H, J and K bands have been obtained on 16 March 2000 using ADONIS at the ESO 3.6 m telescope at La Silla (Chile), allowing us to fully resolve the faint visual companion of RXJ 0529.4+0041 at a separation of about 1.3 arcsec to the North-East. At the time of the observation, Component A, i.e. the eclipsing binary, was out of eclipse, yielding a combined J magnitude of 11.0, and J-H and H-K colors of 0.4 and 0.2, respectively. The visual companion is about one magnitude fainter in the J band and its J-H and H-K colors are 0.6 and 0.2, respectively. From these, we derive a spectral type of about M2-M3 for this visual (Component B) companion, whereas the eclipsing binary (Component A) appears consistent with a mix of an early-K star with a late-K component, as also inferred from the spectroscopy.

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© European Southern Observatory (ESO) 2000

Online publication: October 10, 2000