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Astron. Astrophys. 347, 225-234 (1999)

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2. Observations

The spectroscopic observations were obtained at Kitt Peak National Observatory (KPNO) with the 0.9-m coudé feed telescope during 24 consecutive nights in December and January 1997/98. The 8002 TI-5 CCD detector was employed together with grating A, camera 5, the long collimator, and a 280-µm slit to give a resolving power of 38,000 at 6420 Å, or 0.19 Å as judged from the FWHM of unblended Th-Ar comparison-lamp lines. The full wavelength range was 80 Å and each spectrum was exposed for 3600 sec, except the last two which were exposed for 2700 sec. The analog-to-digital units in the continuum correspond to signal-to-noise ratios of around 250:1. Numerous nightly flat fields were co-added and used to remove the pixel-to-pixel variations in the stellar spectra. The TI-5 CCD shows no signs of fringing around 6400 Å and no attempts were made to correct for it other than the standard flat-field division. Continuum fitting with a very low-order polynomial was sufficient to find an excellent continuum solution.

Continuous Johnson UBV, V(I)C, and Strömgren by photometry of HD 12545 is being obtained with three automatic photoelectric telescopes (APTs) at Fairborn Observatory in southern Arizona since late 1996. With Wolfgang-Amadeus, the two 0.75-m twin Vienna Observatory APTs (Strassmeier et al. 1997b), we obtained V(I)C and by photometry, and with the Phoenix-10 0.25-m APT (Seeds 1995), we obtained UBV photometry. All measures were made differentially with respect to HD 12478 (V=7:m 710, V-Ic=1:m 38; Strassmeier & Oláh 1992) as the comparison star and SAO 55178 as the check star. Three measures in VIC and by were taken per night by Wolfgang-Amadeus and one in UBV by the Phoenix-10. One observation consisted of three ten-second (30-sec in by ) integrations on the variable, four integrations on the comparison star, two integrations on the check star, and two integrations on the sky. A 30" diaphragm was used with Wolfgang-Amadeus and a 60" diaphragm on the Phoenix-10. The standard error of a nightly mean from the overall seasonal mean was for Wolfgang 0:m 003 in by, for Amadeus 0:m 004 in V and 0:m 006 in Ic, and for the Phoenix-10 0:m 009 in BV and 0:m 02 in U. For further details we refer to Strassmeier et al. (1997a, 1997b).

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© European Southern Observatory (ESO) 1999

Online publication: June 18, 1999