First Observations of Clusters with the Advanced Camera for Surveys of the Hubble Space Telescope


March 31 April 4, 2003



The Advanced Camera for Surveys is a new powerful camera that was fitted to the Hubble Space Telescope in March 2002. Many participants of the workshop are members of the ACS Science Team (AST). Because of their contribution in developing the ACS, NASA awarded the ACS Science Team about 650 orbits of observing time on Hubble. These data are being taken during the period 2002 2005.


The major scientific goal of the AST in using their guaranteed time (~300 orbits) is to use the superior sensitivity, wide field and angular resolution of the ACS to study clusters of galaxies over a huge range of distance, ranging from the nearby Universe to the most distant galaxy structures known.


The ACS data (unique spatial resolution) will be compared with ground-based data from large telescopes, such as the VLT (kinematics and colors). The aims will be to use the new ACS data to constrain the formation and evolution of galaxy clusters.


At the time of the workshop, the first year of data had been obtained. Hence the goal was to bring together the participants of the "evolution of galaxies" group, to present and discuss the first data, and to prepare drafts of papers. The Lorentz Center is ideally suited for this project as it allowed informal discussions, and further progress on the data analysis during the meeting. It was the first time that the results were discussed in this informal way, and it was extremely fruitful. The participants came from all over the world (Japan to west coast USA, Chile, etc). The format of the workshop consisted of formal presentations, group discussion sessions, and "work".


We are very thankful for the excellent support by staff of the Lorentz Center. All local travel arrangements were well taken care of, and the facilities were fully available for our use. Fortunately most of the travel costs were financed by the Science Team, we thank the Lorentz Center for the additional financial support for this meeting.


M. Franx (Leiden University, The Netherlands)

G.K. Miley (Leiden University, The Netherlands)