Context. AGILE is an Italian Space Agency mission dedicated to observing the gamma-ray Universe. The AGILE's very innovative instrumentation for the first time combines a gamma-ray imager (sensitive in the energy range 30 MeV-50 GeV), a hard X-ray imager (sensitive in the range 18-60 keV), a calorimeter (sensitive in the range 350 keV-100 MeV), and an anticoincidence system. AGILE was successfully launched on 2007 April 23 from the Indian base of Sriharikota and was inserted in an equatorial orbit with very low particle background. Aims. AGILE provides crucial data for the study of active galactic nuclei, gamma-ray bursts, pulsars, unidentified gamma-ray sources, galactic compact objects, supernova remnants, TeV sources, and fundamental physics by microsecond timing.Methods. An optimal sky angular positioning (reaching 0.1 degrees in gamma-rays and 1-2 arcmin in hard X-rays) and very large fields of view (2.5 sr and 1 sr, respectively) are obtained by the use of Silicon detectors integrated in a very compact instrument. Results. AGILE surveyed the gamma-ray sky and detected many Galactic and extragalactic sources during the first months of observations. Particular emphasis is given to multifrequency observation programs of extragalactic and galactic objects. Conclusions. AGILE is a successful high-energy gamma-ray mission that reached its nominal scientific performance. The AGILE Cycle-1 pointing program started on 2007 December 1, and is open to the international community through a Guest Observer Program.

We present the first stellar density profile of the Milky Way bulge that reaches latitude b = 0• . The profile was derived by counting red clump stars within the colour-magnitude diagram that was constructed using the new PSF-fitting photometry from VISTA Variables in the Vía Láctea (VVV) survey data. The new stellar density map covers the area between |l| ≤ 10• and |b| ≤ 4.5• with unprecedented accuracy, allowing the stellar kinematics from the Giraffe Inner Bulge Spectroscopic Survey (GIBS) to be linked to the stellar mass density distribution. In particular, the location of the central velocity-dispersion peak from GIBS matches a high over-density in the VVV star count map. By scaling the total luminosity function (LF) obtained from all VVV fields to the LF from Zoccali et al. (2003), we obtain the first fully empirical estimate of the mass in stars and in remnants of the Galactic bulge. Within (|b| < 9.5• , |l| < 10 • ), the Milky Way bulge stellar mass is 2.0 ± 0.3 × 10 10 M .

Adaptive-optics systems can in principle allow a telescope to achieve performance at its theoretical maximum (limited only by diffraction), by correcting in real time for the distortion of starlight by atmospheric turbulence. For such a system installed on an 8-m-class telescope, the spatial resolution and sensitivity could be up to 100 times better than conventional imaging. Adaptive-optics corrections have hitherto been achieved only for regions of the sky within a few arcseconds of a bright reference source. But it has been proposed theoretically that by using multiple guide stars, the tomography of atmospheric turbulence could be probed and used to extend adaptive-optics corrections to the whole sky. Here we report the experimental verification of such tomographic corrections, using three off-axis reference stars approximately 15 arcsec from the central star. We used the observations of the off-axis stars to calculate the deformations of the wavefront of the central star, and then compare them with the real measured values. This tomographic approach is found to reduce variations in the wavefront by approximately 92%. Our result demonstrates that a serious barrier to achieving diffraction-limited seeing over the whole sky has been removed.

We present a new method to estimate the absolute ages of stellar systems. This method is based on the difference in magnitude between the main sequence turn-off (MSTO) and a well defined knee located along the lower main sequence (MSK). This feature is caused by the collisionally induced absorption of molecular hydrogen and it can be easily identified in near-infrared (NIR) and in optical-NIR color-magnitude diagrams of stellar systems. We took advantage of deep and accurate NIR images collected with the Multi-Conjugate Adaptive Optics Demonstrator temporarily available on the Very Large Telescope and of optical images collected with the Advanced Camera for Surveys Wide Field Camera on the Hubble Space Telescope and with ground-based telescopes to estimate the absolute age of the globular NGC 3201 using both the MSTO and the ∆(MSTO-MSK). We have adopted a new set of cluster isochrones and we found that the absolute ages based on the two methods agree to within one sigma. However, the errors of the ages based on the ∆(MSTO-MSK) method are potentially more than a factor of two smaller, since they are not affected by uncertainties in cluster distance or reddening. Current isochrones appear to predict slightly bluer (≈0.05 mag) NIR and optical-NIR colors than observed for magnitudes fainter than the MSK. Subject headings: globular clusters: individual (NGC3201) -stars: evolution -stars: fundamental parameters 1 Based on near infrared observations made with ESO telescopes SOFI@NTT, La Silla; MAD@VLT Paranal, projects: 66.D-0557, 074.D-0655, ID96406 and with the CTIO telescope ISPI@4m Blanco, La Serena. Based on optical data collected with ESO telescopes and retrieved from the ESO Science Archive Facility.

We present a new complete Near-Infrared (NIR, JHK s ) census of RR Lyrae stars (RRLs) in the globular ω Cen (NGC 5139). We collected 15,472 JHK s images with 4-8m class telescopes over 15 years (2000)(2001)(2002)(2003)(2004)(2005)(2006)(2007)(2008)(2009)(2010)(2011)(2012)(2013)(2014)(2015) covering a sky area around the cluster center of 60×34 arcmin 2 . These images provided calibrated photometry for 182 out of the 198 cluster RRL candidates with ten to sixty measurements per band. We also provide new homogeneous estimates of the photometric amplitude for 180 (J), 176 (H) and 174 (K s ) RRLs. These data were supplemented with single-epoch JK s magnitudes from VHS and with single-epoch H magnitudes from 2MASS. Using proprietary optical and NIR data together with new optical light curves (ASAS-SN) we also updated pulsation periods for 59 candidate RRLs. As a whole, we provide JHK s magnitudes for 90 RRab (fundamentals), 103 RRc (first overtones) and one RRd (mixed-mode pulsator). We found that NIR/optical photometric amplitude ratios increase when moving from first overtone to fundamental and to long-period (P>0.7 days) fundamental RRLs. Using predicted Period-Luminosity-Metallicity relations, we derive a true distance modulus of 13.674±0.008±0.038 mag (statistical error and standard deviation of the median)-based a This publication makes use of data gathered with the Magellan/Baade Telescope at Las Campanas Observatory, the Blanco Telescope at Cerro Tololo Inter-American Observatory, NTT at La Silla (ESO Program IDs: 64.N-0038(A), 66.D-0557(A), 68.D-0545(A), 073.D-0313(A), ID 073.D-0313(A) and 59.A-9004(D)), VISTA at Paranal (ESO Program ID: 179.A-2010) and VLT at Paranal (ESO Program ID: ID96406).RRc RRab Global DM err a σ b DM err a σ b DM err a σ b mag mag mag mag mag mag mag mag mag -[Fe/H] from Sollima et al. (2006a)--Theoretical calibration-J 13.658 0.009 0.047 13.656 0.012 0.029 13.655 0.009 0.035 H 13.675 0.006 0.044 13.676 0.008 0.034 13.674 0.006 0.033 K s 13.697 0.005 0.041 13.687 0.007 0.026 13.690 0.005 0.029 mean JHKs 13.677 0.007 0.047 13.673 0.009 0.032 13.673 0.007 0.036 Overall mean: 13.674±0.008±0.038 -Empirical calibration-J 13.693 0.016 0.027 13.809 0.017 0.062 13.755 0.011 0.031 H 13.666 0.015 0.032 13.791 0.017 0.032 13.766 0.010 0.031 K s 13.707 0.015 0.034 13.819 0.017 0.025 13.772 0.010 0.029 mean JHKs 13.689 0.015 0.035 13.806 0.017 0.045 13.764 0.010 0.031 Overall mean: 13.757±0.014±0.056 -[Fe/H] from Braga et al. (2016)--Theoretical calibration-J 13.681 0.005 0.045 13.677 0.006 0.036 13.675 0.004 0.048 H 13.694 0.004 0.041 13.706 0.005 0.041 13.699 0.003 0.045 K s 13.723 0.003 0.045 13.713 0.005 0.037 13.720 0.003 0.051 mean JHKs 13.699 0.004 0.047 13.699 0.005 0.041 13.698 0.004 0.052 Overall mean: 13.698±0.004±0.048 -Empirical calibration-J 13.725 0.009 0.031 13.853 0.012 0.034 13.767 0.006 0.036 H 13.691 0.008 0.030 13.819 0.011 0.036 13.772 0.005 0.037 K s 13.742 0.008 0.032 13.839 0.011 0.037 13.791 0.005 0.039 mean JHKs 13.719 0.008 0.037 13.837 0.012 0.038 13.777 0.005 0.039Ove...