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Aims. We attempt to measure the main physical properties (mass, velocity dispersion, and total luminosity) of the cluster Abell 2163.

Ghost imaging is a phenomenon that attracted many physicists from the community in the last years, due to the different configurations by which it can be realised, but principally due to the wide discussion about its quantum or classical nature. Here we analyse a ghost imaging scheme realised in frequency downconversion, which is intrinsically a quantum interaction, from a classical point of view and, by means of a computer simulation, we also show that this description holds provided that the seed field is bright enough.

We analyze a frequency degenerate two-arm seeded downconversion process in which the seed fields are spatially multimode chaotic fields. We prove that the output state exhibits a transition from entanglement to separability as far as the intensities of the seeds increase, whereas it is suitable for a ghost imaging experiment irrespective of its entanglement properties. Furthermore we present two experiments of ghost imaging with good visibilty based on parametric downconversion seeded on a single arm.

We present the Capodimonte Deep Field (OACDF), a deep field covering an area of 0.5 $\deg ^2$in the B, V, Roptical bands plus six medium-band filters in the wavelength range 773–913 nm. The field reaches the following limiting magnitudes: $B_{AB}\sim 25.3$, $V_{AB}\sim 24.8$and $R_{AB}\sim25.1$and contains ~50 000 extended sources in the magnitude range 18 $\le R_{AB} \le 25.0$. Hence, it is intermediate between deep pencil beamsurveys and very wide but shallow surveys. The main scientific goal of the OACDF is the identification and characterization of early-type field galaxies at different look-back times in order to study different scenarios of galaxy formation. Parallel goals include the search for groups and clusters of galaxies and the search for rare and peculiar objects (gravitational lenses, QSOs, halo White Dwarfs). In this paper we describe the OACDF data reduction, the methods adopted for the extraction of the photometric catalogs, the photometric calibration and the quality assessment of the catalogs by means of galaxy number counts, spectroscopic and photometric redshifts and star colors. We also present the first results of the search for galaxy overdensities. The depth of the OACDF and its relatively large spatial coverage with respect to pencil beam surveys make it a good tool for further studies of galaxy formation and evolution in the redshift range 0–1, as well as for stellar studies.

By means of CCD photometry in three bands (Gunn g, r, i) we investigate the existence of 12 candidate clusters extracted via a model independent peak finding algorithm ([CITE]) from DPOSS data. The derived color-magnitude diagrams allow us to confirm the physical nature of 9 of the cluster candidates, and to estimate their photometric redshifts. Of the other candidates, one is a fortuitous detection of a true cluster at $z \sim 0.4$, one is a false detection and the last is undecidable on the basis of the available data. The accuracy of the photometric redshifts is tested on an additional sample of 8 clusters with known spectroscopic redshifts. Photometric redshifts turn out to be accurate within $z \sim 0.01$(interquartile range).

The composite galaxy luminosity function (hereafter LF) of 39 Abell clusters of galaxies is derived by computing the statistical excess of galaxy counts in the cluster direction with respect to control fields. Due to the wide field coverage of the digitised POSS-II plates, we can measure field counts around each cluster in a fully homogeneous way. Furthermore, the availability of virtually unlimited sky coverage allows us to directly compute the LF errors without having to rely on the estimated variance of the background. The wide field coverage also allows us to derive the LF of the whole cluster, including galaxies located in the cluster outskirts. The global composite LF has a slope $\alpha\sim-1.1\pm0.2$with minor variations from blue to red filters, and $M^*\sim-21.7,-22.2,-22.4$mag ($H_0=50$km s-1Mpc-1) in $g, r$and ifilters, respectively (errors are detailed in the text). These results are in quite good agreement with several previous determinations and in particular with the LF determined for the inner region of a largely overlapping set of clusters, but derived making use of a completely different method for background subtraction. The similarity of the two LFs suggests the existence of minor differences between the LF in the cluster outskirts and in the central region, or a negligible contribution of galaxies in the cluster outskirts to the global LF.

Abstract.: We analyze a frequency degenerate two-arm seeded downconversion process in which the seed fields are spatially multimode chaotic fields. We prove that the output state exhibits a transition from entanglement to separability as far as the intensities of the seeds increase, whereas it is suitable for a ghost imaging experiment irrespective of its entanglement properties. Furthermore we present two experiments of ghost imaging with good visibilty based on parametric downconversion seeded on a single arm.

Abstract.: Ghost imaging is a phenomenon that attracted many physicists from the community in the last years, due to the different configurations by which it can be realised, but principally due to the wide discussion about its quantum or classical nature. Here we analyse a ghost imaging scheme realised in frequency downconversion, which is intrinsically a quantum interaction, from a classical point of view and, by means of a computer simulation, we also show that this description holds provided that the seed field is bright enough.

Ghost imaging is a phenomenon that attracted many physicists from the community in the last years, due to the different configurations by which it can be realised, but principally due to the wide discussion about its quantum or classical nature. Here we analyse a ghost imaging scheme realised in frequency downconversion, which is intrinsically a quantum interaction, from a classical point of view and, by means of a computer simulation, we also show that this description holds provided that the seed field is bright enough.

We analyze a frequency degenerate two-arm seeded downconversion process in which the seed fields are spatially multimode chaotic fields. We prove that the output state exhibits a transition from entanglement to separability as far as the intensities of the seeds increase, whereas it is suitable for a ghost imaging experiment irrespective of its entanglement properties. Furthermore we present two experiments of ghost imaging with good visibilty based on parametric downconversion seeded on a single arm.

VST is the acronym for VLT Survey Telescope, a 2.6 m wide-field (WF) imaging telescope conceived and built by the INAF-Capodimonte Astronomical Observatory in Naples (INAF-OAC) chiefly to serve the ESO VLT at the Cerro Paranal Observatory. The VST will be equipped with a 16 K × 16K mosaic camera built by the European consortium OmegaCam. The system shall cover a corrected field of view of 1 square degree with a pixel scale of 0.21 arcsec. The expected average data rate will be about 150 GB per night; a flood of data implying suitable HW/SW facilities. ESO, operating the telescope at Paranal, will reserve about 20% of the VST observing time to INAF-OAC in return for the procurement of the instrument. The INAF-OAC core program planned for this time includes a galactic and an extragalactic survey, a SN search campaign, and an extended monitoring of the minor bodies of the Solar System. In this paper we describe the data flow, the data model, and the features of the processing system under development. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Aims.We use deep CFHT and SUBARU uBVRIzarchival images of the Abell 383cluster (z= 0.187) to estimate its mass by weak-lensing.