We present a new method to solve for the star-formation history (SFH) of a complex stellar population system from the analysis of the color-magnitude diagram (CMD). The SFH is obtained in four steps: i) computing a synthetic CMD, ii) simulating observational effects, iii) parameterization and sampling of the synthetic and observed CMDs, and iv)

We report recent observations of M31 taken with Chandra/ACIS-I on 2009-05-29.1 UT and with Swift/XRT on 2009-06-07.08 UT. In the 4ks Chandra/ACIS-I image, we found a faint transient located at R.A.(J2000)=00h42m26.7s, Decl. (J2000)=+41:13:46.5 with a 90% absolute error of 0.6 arcsec. It is therefore identified as CXOM31 J004226.7+411346. The

EC14012-1446 is a hydrogen atmosphere (DA) white dwarf pulsator. Its rich pulsation spectrum displays a range of excited modes with complex multiplet structure, in addition to numerous combination frequencies. In April 2008, EC14012-1446 was the primary target of XCOV26. We obtained over 300 hrs of nearly continuous high speed photometry with the

The Active Phasing Experiment (APE) has been used by ESO to gain experience in controlling segmented primary mirrors in preparation for the European Extremely Large Telescope. The experiment tested various phasing techniques and explored their advantages and limitations. Four optical phasing sensors were developed using different techniques — a

We present Integral Field Unit GMOS-IFU data of the compact H II galaxy UM 408, obtained at the Gemini South telescope, in order to derive the spatial distribution of emission lines and line ratios, kinematics, plasma parameters, and oxygen abundances as well the integrated properties over an area of 3''×4farcs4 equivalent with ~750 pc × 1100 pc

We show a selection of high-sensitivity spectropolarimetric observations obtained over the last few years in the Ba II D_2-line with the Zürich Imaging Polarimeter (ZIMPOL) attached to the Gregory Coudé Telescope of IRSOL. The measurements were collected close to the solar limb, in several regions with varying degree of magnetic activity. The