2. Observations and data reduction
In 1996 spectroscopic observations were carried out with the coudé spectrograph on the 2.6 m telescope of the Crimean Astrophysical Observatory. The spectra were obtained with the 1st camera equipped with a CCD detector SDS 9000, Photometrics GmbH of 1024400 pixels. With the slit of 04 and dispersion of 65 mÅ/pix a resolving power of about 40 000 was achieved. The covered spectral range was about 60 Å centered at 6170 Å. Two exposures of 20 min were typically obtained, that provided the signal-to-noise ratio of an individual exposure of about 250.
In 1997 the star was observed with the SOFIN échelle spectrograph fed by the 2.56 m Nordic Optical Telescope (NOT), La Palma, Canarias. The data were acquired with the 2nd camera equipped with a CCD detector of 1152298 pixels. Two échelle frames centered at 6180 Å and 7055 Å almost completely covered the spectral range of approximately 5500-8500 Å. For all observing runs the projected width of the slit was set to be 05 on the sky, providing a spectral resolving power 83 000. With this setup, the dispersion at 6170 Å was 37 mÅ/pix. A typical exposure time of 15 min achieved a signal-to-noise ratio of about 200 for most spectra.
The reduction of the SOFIN data, described by Ilyin (1997), included bias, scattered light, and flat-field corrections, extraction of spectral orders, and wavelength calibration. The latter is obtained with a thorium-argon comparison spectrum. Finally, the wavelengths were corrected for the Earth's motion. The Crimean spectra were reduced similarly except for the steps specifically relating to the échelle spectra. The Julian dates of all spectroscopic observations are given in Table 1.
Table 1. Radial velocities data.
© European Southern Observatory (ESO) 1999
Online publication: June 6, 1999