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Astron. Astrophys. 364, 349-368 (2000)

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2. Observations

The data were obtained during the spring of 1998 using the prime-focus wide-field UH8K CCD Camera (Metzger et al., 1995) at the Canada-France-Hawaii 3.6 m Telescope. The camera is a mosaic of 8 2k[FORMULA]4k CCD chips covering a total area of [FORMULA] with a scale of [FORMULA]/pixel. We observed four fields with R.A. offset of [FORMULA], and [FORMULA], hence overlapping by 5´, 5´ and 10´ (Table 1). The observations were done in bands V (Johnson) and I (Cousins). The total area of the survey is 0.68 deg2. The limiting magnitudes are [FORMULA] and [FORMULA] (see Sect. 3.3 on the completeness). The central galactic coordinates are [FORMULA], [FORMULA]. At such high galactic latitudes, the reddening is [FORMULA] mag (Burstein & Heiles, 1982). This is an upper limit because we observed in V and I (reddening[FORMULA]). We neglect both the absolute reddening and the relative reddening between the fields. Table 1 gives the characteristics of each field. The seeing is between [FORMULA] and [FORMULA] for both filters during the whole night. The exposure time is 1200 sec for all fields. Fig. 1 shows the map of the [FORMULA]19,500 galaxies detected to [FORMULA] (limiting magnitude of the correlation analysis, cf Sect. 3.3). In spite of the bad cosmetics of CCD#4 (visible in the upper right corner of Fig. 1), the [FORMULA] overlaps provide homogeneous sampling of the area, except for the regions containing bright stars (empty circle in the upper middle) and the gaps within the UH8K Mosaic CCD chips.

[FIGURE] Fig. 1. Map of 19,506 galaxies to [FORMULA]. Bad cosmetics, intervals between CCD chips, and saturation artifacts due to bright stars are masked (shown as empty areas).


Table 1. Field characteristics

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© European Southern Observatory (ESO) 2000

Online publication: January 29, 2001