All Figures

Figure 1: The ESIS VIMOS survey in ELAIS-S1 and the multiwavelength coverage of the area. The shaded area represents the 49 ESIS VIMOS pointings in the I(blue/dark) and I+z (red/light) bands. Over plotted are: the ESIS WFI survey (  squares Berta et al. 2006) and the SWIRE (Lonsdale et al. 2003,2004), XMM (Puccetti et al. 2006), ELAIS ISO (e.g. Rowan-Robinson et al. 2004), ATCA 1.4 GHz (Middelberg et al. 2007; Gruppioni et al. 1999) areas.

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In the text

	Figure 2: Scheme of the ESIS VIMOS observing strategy. Left panel: each pointing is made of three different OBs, shifted in the sky in order to fill gaps between CCDs. Right panel: each OB consists of four dithered exposures, for optimal bad pixels masking.
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In the text

	Figure 3: The VIMOS I and z passbands average transmissivity.
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In the text

	Figure 4: Example of de-fringing process in the I band.
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In the text

Figure 5: Determination of VIMOS zeropoints. Top panels: two examples of SED fitting of stars in ESIS photometric pointings. The open squares represent the I and z band expected fluxes derived from the best fit. Bottom left panel: selection of point-like objects on the z band photometric images used to derive zeropoints. The dark dots represent the ``stellar'' locus. Bottom right panel: z band zeropoint for CCD 4. The dashed line represents the median, the dotted lines are the  levels used for clipping the data.

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In the text

	Figure 6: The ESIS VIMOS final I band mosaic.
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In the text

	Figure 7: The ESIS VIMOS final z band mosaic.
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In the text

	Figure 8: The ESIS VIMOS final I ( left) and z band ( right) exposure maps. Brighter regions correspond to deeper coverage. North is up, east is left; the two images have roughly the same scale.
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In the text

Figure 9: Examples of defects to be masked before mosaicking. Top panels show emission features: optical reflections and satellite trails. Bottom panels exemplify ``vignetting'' features: the unidentified shadow causing residual gaps in the final mosaics ( left) and the shadow of the guide star probe ( right). For the sake of clarity we have inverted colors of the shadows. North is up, east is left.

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In the text

	Figure 10: Actual FWHM of pointlike sources in the ESIS VIMOS I band ( top panels) and z band ( bottom panels) survey. The dependence on magnitude and the variation of FWHM across the field are shown. Grey levels and dot dimensions illustrate seeing properties, darker and smaller dots referring to better FWHM. Three bins are considered: , , .
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In the text

Figure 11: Astrometric accuracy of the ESIS VIMOS survey. Left panels: I band. The top and central plots show the displacement of ESIS coordinates with respect to the GSC 2.2 (STScI & OaTO, 2001) catalog. The bottom figure shows the relative astrometric accuracy between the 9 different I band sub-areas. Right panels: same plots for the z band. Only absolute astrometry is shown, because the z band covers 1 deg2 and consists of one single final mosaic. Horizontal solid lines set the levels of .

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In the text

	Figure 12: Photometric accuracy, derived by extracting synthetic point-like sources from ESIS VIMOS I band ( left) and z band ( right) mosaics. Different panels refer to different effective depths. Solid, short-dashed and long-dashed lines trace the median, the 1- and the s.i.q.r. levels respectively.
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In the text

	Figure 13: Detection rate as a function of magnitude, from simultaed point-like sources. The vertical dotted lines show the 90% and 95% completeness levels.
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In the text

	Figure 14: Observed source number counts for the ESIS VIMOS survey, split into effective depth bins ( top panels) and into point-like vs. extended sources ( bottom panels). Literature data belong to: COSMOS (Taniguchi et al. 2007; Scoville et al. 2007a), GOODS-N (Capak et al. 2004), VVDS (McCracken et al. 2003), HDFN, HDFS, William Herschel (WHDF Metcalfe et al. 2001), SDSS (Yasuda et al. 2001).
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In the text

	Figure 15: Selection of point-like sources based on the half-flux radius or SExtractor's stellarity flag ( right-hand panel), for the z band. Darker dots represent point-like objects.
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In the text

Figure 16: Color-color plots adopted in the selection of IR-peakers. Filled triangles and circles represent 5.8 m-peakers and 4.5 m-peakers respectively. Open circles are 4.5 m-peakers identified as low-redshift interlopers on the basis of . Small dots trace the general SWIRE-ESIS population; orange dots are general sources with no 8.0 m detection (upper limits are used). Redshift tracks for different templates are plotted: M 82 (dusty starburst) and M 51 (spiral) belong to the GraSil library (Silva et al. 1998); the Sy1 and Sy2 templates represent Mrk231 and IRAS 19254-7245 (Berta et al. 2003; Fritz et al. 2006). The black thick solid lines in the BzK diagram ( bottom-right panel) represent three GraSil spiral models with no extinction (ages 0.2, 1.0, 2.0 Gyr) and one GraSil elliptical (age 3 Gyr). Redshift values are reported along tracks. The diagonal and vertical dashed lines in the left-hand diagrams represent the color conditions to identify low-redshift interlopers (see text).

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In the text

	Figure 17: Photometric redshift tests on galaxies in the SWIRE-ESIS field, run with EAZY code (Brammer, van Dokkum & Coppi, ApJ, submitted). Left: all photometric bands; center: all bands excepted I and z; right: GALEX, I and IRAC only. The dashed lines mark the  scatter in . Spectroscopic data belong to Feruglio et al. (sub.), Sacchi et al. (in prep.) and La Franca et al. (2004).
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In the text