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The End of the White Dwarf Cooling Sequence in M4: An Efficient Approach
We use 14 orbits of Advanced Camera for Surveys observations to reach the end of the white dwarf cooling sequence in the globular cluster M4. Our photometry and completeness tests show that the endExpand
Hubble Space Telescope Observations of an Outer Field in Omega Centauri: A Definitive Helium Abundance
We revisit the problem of the split main sequence (MS) of the globular cluster ω Centauri, and report the results of two-epoch Hubble Space Telescope observations of an outer field, for which properExpand
Astrometry and Photometry with HST WFC3. II. Improved Geometric-Distortion Corrections for 10 Filters of the UVIS Channel*
We present an improved geometric-distortion solution for the Hubble Space Telescope UVIS chan- nel of Wide Field Camera 3 for 10 broadband filters. The solution is made up of three parts: (1) aExpand
Color-Magnitude Diagrams and Luminosity Functions Down to the Hydrogen-Burning Limit. III. A Preliminary Hubble Space Telescope Study of NGC 6791
Using Hubble Space Telescope Advanced Camera for Surveys Wide Field Channel images, we derive the color-magnitude diagram of the old, metal-rich open cluster NGC 6791 to nearly 29th magnitude in V,Expand
Ground-based CCD astrometry with wide field imagers - I. Observations just a few years apart allow decontamination of field objects from members in two globular clusters
This paper is the first of a series of papers in which we will apply the methods we have developed for high-precision astrometry (and photometry) with the Hubble Space Telescope to the case ofExpand
The absolute motion of the peculiar cluster NGC 6791
We present improved values of the three components of the absolute space velocity of the open cluster NGC 6791. One HST ACS/WFC field with two-epoch observations provides astrometric measurements ofExpand
The puzzling white dwarf cooling sequence in NGC 6791: A simple solution
In this Letter we demonstrate that the puzzling bright peak in the luminosity function of the white dwarf (WD) cooling sequence of NGC 6791 can be naturally accounted for if ~34% of the observed WDsExpand
Hubble Space Telescope observations of the Kepler-field cluster NGC 6819 - I. The bottom of the white dwarf cooling sequence
JA and IRK acknowledge support from STScI grant GO-11688 and GO-12669. PB was supported in part by the NSERC Canada and by the Fund FRQ-NT (Quebec).
The White Dwarf Cooling Sequence of NGC 6397
We present the results of a deep Hubble Space Telescope (HST) exposure of the nearby globular cluster NGC 6397, focussing attention on the cluster's white dwarf cooling sequence. This sequence isExpand
The bottom of the white dwarf cooling sequence in the old open cluster NGC 2158
We use 10 orbits of Advanced Camera for Surveys observations to reach the end of the white dwarf cooling sequence in the solar-metallicity open cluster NGC 2158. Our photometry and completeness testsExpand