Aims. We present the characteristics and some early scientific results of the first instrument at the Large Binocular Telescope (LBT), the Large Binocular Camera (LBC). Each LBT telescope unit will ...be equipped with similar prime focus cameras. The blue channel is optimized for imaging in the $UV-B$ bands and the red channel for imaging in the VRIz bands. The corrected field-of-view of each camera is approximately 30 arcmin in diameter, and the chip area is equivalent to a 23$\times$23 arcmin2 field. In this paper we also present the commissioning results of the blue channel. Methods. The scientific and technical performance of the blue channel was assessed by measurement of the astrometric distortion, flat fielding, ghosts, and photometric calibrations. These measurements were then used as input to a data reduction pipeline applied to science commissioning data. Results. The measurements completed during commissioning show that the technical performance of the blue channel is in agreement with original expectations. Since the red camera is very similar to the blue one we expect similar performance from the commissioning that will be performed in the following months in binocular configuration. Using deep UV image, acquired during the commissioning of the blue camera, we derived faint UV galaxy-counts in a ~ 500 sq. arcmin sky area to U(Vega) = 26.5. These galaxy counts imply that the blue camera is the most powerful UV imager presently available and in the near future in terms of depth and extent of the field-of-view. We emphasize the potential of the blue camera to increase the robustness of the UGR multicolour selection of Lyman break galaxies at redshift z ~ 3.
Context. Deep multicolour surveys are the main tool for exploring the formation and evolution of the very faint galaxies that are beyond the spectroscopic limit of present technology. The photometric ...properties of these faint galaxies are usually compared with current renditions of semianalytical models to provide constraints on the detailed treatment of the fundamental physical processes involved in galaxy formation and evolution, namely the mass assembly and the star formation. Aims. Galaxy counts over large sky areas in the 360 nm near-UV band are particularly difficult to obtain given the low efficiency of near-UV instrumentation, even at 8 m class telescopes. Observing in the near-UV bands can provide a first assessment of the distribution of star formation activity in distant (up to z ~ 3) galaxies. A relatively large instrumental field of view helps to minimize the biases caused by cosmic variance. Methods. We obtained deep images in the 360 nm U band provided by the blue channel of the Large Binocular Camera at the prime focus of the Large Binocular Telescope. Over an area of $\simeq$0.4 sq. deg., we derived the galaxy number counts down to $U = 27$ in the Vega system (corresponding to $U = 27.86$ in the AB system) at a completeness level of 30% reaching the faintest current limit for this wavelength and sky area. Results. The shape of the galaxy number counts in the U band can be described by a double power-law, the bright side being consistent with the shape of shallower surveys of comparable or greater areas. The slope bends over significantly at $U > 23.5$ ensuring the convergence of the contribution by star-forming galaxies to the extragalactic background light in the near-UV band to a value that is more than 70% of the most recent upper limits derived for this band. We jointly compared our near-UV and K band counts collected from the literature with a few selected hierarchical CDM models, concentrating on specific critical issues in the physical description of the galaxy formation and evolution.
We used a proper combination of high-resolution and wide-field multiwavelength observations collected at three different telescopes (HST, LBT, and CFHT) to probe the blue straggler star (BSS) ...population in the globular cluster M53. Almost 200 BSSs have been identified over the entire cluster extension. The radial distribution of these stars has been found to be bimodal (similar to that of several other clusters) with a prominent dip at image60 super(image ) from the cluster center. This value turns out to be a factor of 2 smaller than the radius of avoidance (image, the radius within which all the stars of image1.2 image have sunk to the core because of dynamical friction effects in a Hubble time). While in most of the clusters with a bimodal BSS radial distribution, image has been found to be located in the region of the observed minimum, this is the second case (after NGC 6388) where this discrepancy is noted. This evidence suggests that in a few clusters the dynamical friction seems to be somehow less efficient than expected. We have also used this database to construct the radial star density profile of the cluster; this is the most extended and accurate radial profile ever published for this cluster, including detailed star counts in the very inner region. The star density profile is reproduced by a standard King Model with an extended core (image25 super(image )) and a modest value of the concentration parameter. A deviation from the model is noted in the most external region of the cluster (at image from the center). This feature needs to be further investigated in order to address the possible presence of a tidal tail in this cluster.
In the first part of this work we describe a new relational database (DB) created for storing metadata of stellar evolution models for a large range of masses and initial chemical compositions, which ...allows searching for data by scientific quantities and useful parameters. These data users can access the DB and might select a good catalog of evolutionary tracks and/or isochrones for making scientific studies and comparison with observational data. We also present a new Web portal where users can download scientific data of interest. This work has been conduced within the Italian Theoretical Virtual Observatory (ITVO) project , which aims to register these theoretical data under the Virtual Observatory standard and provide a set of standard tools able to visualize and analyze observational and also theoretical data. In the second part of the work we describe the link between the Grid infrastructure and the Virtual Observatory services as delineated by G. Taffoni and colleagues in 2006 and by F. Pasian and colleagues in 2008.
In order to offer an intuitive but effective access to a growing number of cosmological simulations, we have developed the Italian Theoretical Virtual Observatory project (ITVO), as described by ...Pasian and colleagues in 2006. In this work we describe two Web portals as two ways to access and share complex data coming from numerical astrophysical simulations. We present a set of Web services aimed at offering services such as Simple Numeric Access (ProtocolSNAPSimple Numeric Access Protocol), as described by Gheller and colleagues in 2006, and Randomizers dealing with different data formats. The Web services technology allows us to run a particular task (a SNAP job, for instance) close to its data, avoiding an expensive data transfer.
Aims.We present a 900 s, wide-field U image of the inner region of the Andromeda galaxy obtained during the commissioning of the blue channel of the Large Binocular Camera mounted on the prime focus ...of the Large Binocular Telescope. Methods.Relative photometry and absolute astrometry of individual sources in the image was obtained along with morphological parameters aimed at discriminating between stars and extended sources, e.g. globular clusters. Results.The image unveils the near-ultraviolet view of the inner ring of star formation recently discovered in the infrared by the Spitzer Space Telescope and shows in great detail the fine structure of the dust lanes associated with the galaxy inner spiral arms. The capabilities of the blue channel of the Large Binocular Camera at the Large Binocular Telescope (LBC-Blue) are probed by direct comparison with ultraviolet GALEX observations of the same region in M 31. We discovered 6 new candidate stellar clusters in this high-background region of M 31. We also recovered 62 bona-fide globulars and 62 previously known candidates from the Revised Bologna Catalogue of the M 31 globular clusters, and firmly established the extended nature of 19 of them.
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