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2. The observations

2.1. Photometry

New and unpublished photometric data of HD 45677 in the Walraven WULBV, Strömgren uvby, Johnson/Cousins tex2html_wrap_inline2499 and ESO JHKLM system are listed in an accompanying paper (de Winter et al. 1996; Paper I) and will be analyzed and discussed in this paper.

2.2. Spectroscopy

Several new low resolution CCD spectra of HD 45677 were taken at La Silla using the Boller and Chivens spectrograph mounted on the ESO 1.52 m telescope. Details of the observations are given in Table 1 (click here). In order to get a sufficiently good S/N for weaker emission lines it was necessary to have the strength of Htex2html_wrap_inline2503 exceed the CCD saturation limit. To be able to measure the relative strength of Htex2html_wrap_inline2505 second, shorter, exposures during the same two December nights were taken in which Htex2html_wrap_inline2507 was not saturated. A combined spectrum of the 1992 d, e, f and 1992 g spectra is presented in Fig. 4 (click here).

Table 1: Log of published and newly taken optical spectroscopic observations of HD 45677

To reveal the Htex2html_wrap_inline2555 profile and to test for short time scale variations two intermediate resolution spectra, Fig. 5 (click here), centered around Htex2html_wrap_inline2557, were obtained. These observations, see Table 1 (click here), were made with the Boller and Chivens spectrograph mounted on the ESO 1.52 m telescope at La Silla. The detector for all the low and intermediate resolutions taken spectra was a Ford Aerospace 2048tex2html_wrap_inline25592048 pixel CCD, with a 15tex2html_wrap_inline256115 tex2html_wrap_inline2563m pixel size.

To detect short time scale variations, HD 45677 was followed day to day between the 8tex2html_wrap_inline2565 and the 14tex2html_wrap_inline2567 of October 1993 by using the CAT/CES combination at La Silla. This combination was used to obtain high resolution spectra in the Htex2html_wrap_inline2569 and NaID wavelength ranges, which are presented in Figs. 9 and 10. Further high resolution spectra, in the Htex2html_wrap_inline2573, CaIIK, and [OI] 6300 Å wavelength ranges (Figs. 6-8), were obtained in January 1994. During all observations, the detector was a 1024 tex2html_wrap_inline2577 640 RCA SID 006 high resolution CCD, with a pixel size of 15tex2html_wrap_inline257915 tex2html_wrap_inline2581m. All the CAT/CES observations were controlled remotely from ESO Headquarters, Garching bei München, Germany.

All spectra were reduced using the MIDAS software running under SUN/OS at ESO headquarters. For optimal extraction of spectral data from the CCD images the optimal extraction algorithm by Horne (1986) was applied. After reduction, the low-resolution spectra were combined into one single, completely unsaturated, spectrum, with spectrophotometric quality. The new spectral data are shown in Figs. 4-10. Additional details of all spectroscopic observations are listed in Table 1 (click here).

2.3. Imaging

Images of HD 45677 were obtained, under reasonable (1tex2html_wrap2611 1-1tex2html_wrap2613 6) seeing conditions, with the Dutch 92 cm telescope at La Silla. Two observing runs were used, on the 10tex2html_wrap_inline2589 and 14tex2html_wrap_inline2591 of February 1993, and on the 7tex2html_wrap_inline2593 of August 1993. The images were reduced using MIDAS, running on a VAX cluster at the University of Amsterdam. On all of the images, taken through B, V, R, Gunn i, Gunn z, wideband Htex2html_wrap_inline2605, narrowband Htex2html_wrap_inline2607 and narrowband [OI]tex2html_wrap_inline26096300 filters, HD 45677 was indistinguishable from a stellar point source. No nebulosity of emission or reflection nature were visible. By checking POSS (Palomar Observatory Sky Survey) plates, searching for significant changes of the number of stellar objects in the surroundings of HD 45677, no dark region could be marked.

Figure 1: Light curve of HD 45677. a) Using photographic and photoelectric data from 1899 to 1994. b) Using photoelectric data from 1971 to 1994. The labels A - E denote the different datasets discussed in Sects. 3.2 and 3.3

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