Dear All:

This is an announcement for an organisational meeting of the Planck Working Group concerned with Clusters and Secondary Anisotropies. The Science Team has decided that the Science and Technical Working Groups put together at ESTEC should be merged into a single streamlined set of WG’s to steer activity within the project (see the Planck Newsletter of this summer). The goal of the meeting is to reach consensus on the appropriate structure for this Working Group, on an outline work plan for the next several years, and on a list of names of possible coordinators for the various sub-activities. The outcome should be a detailed proposal which the Science Team can adjust to mesh with the activities of other Working Groups.

The letter is being sent to the full collaboration mailing list in order to ensure that no interested participant is overlooked. It is intended, however, that attendees should be restricted to those interested in organising and leading Working Group activies in this area. People who expect to contribute to the area but who do not wish to take a significant organisational role should wait until the final group structure is approved by the Science Team. They should then contact the relevant coordinators. We summarise below the science proposals and the possible WG structure which came out of our ESTEC meeting; the names listed there as coordinators are our first guess at the appropriate participant list for this WG meeting, but we are keen to avoid excluding anyone whom we have forgotten and who wishes to contribute.

The meeting will be held in Garching on 19 and 20 of October 2001. This is between the two Instrument Consortium meetings and will avoid the need for a second trip for LFI participants. It will also allow US HFI participants to make only one trip to Europe for this meeting and for the HFI consortium. The planned schedule is 11:30 - 18:00 on Friday 19 and 9:00 to 18:00 on Saturday 20. This leaves Sunday 21 for travel home or to the HFI meeting in Cardiff.

After ESTEC the following subgroups sent proposals in for the Scientific Programme of Planck 3.1 Lensing by Clusters (Bartelmann, van Waerbeke) 3.2 Lensing by LSS (Bernardeau, Baccigalupi) 3.3 Ionization history (Sugiyama, Balbi) 3.4 Integrated SW (Banday, Matarrese) 4.1 Kinetic SZ (Aghanim, Atrio, Hornstrup) 4.2 Prelaunch optical data (White, Rebolo) 4.3 Prelaunch X-ray data (Arnaud, Mazzota) 4.4 Filaments, LSS (Church, Mann) 4.5 Cluster counts (Bartlett, Scott) In addition we suggested at ESTEC the following working structure in our areas with possible coordinators for sub-activities (a couple of names added by us or at ST suggestion since ESTEC) WG5a X-ray catalogue assembly (Arnaud, Mazzotta) WG5b Optical catalogue assembly (Rebolo, White) WG5c Assembly and evaluation of SZ interferometer data (Lasenby, Kneissl) WG5d Assessment of SZ contamination (Giard, Church, Leahy) WG5e Cluster and LSS simulations (Bartelmann, Colombi, Liddle, Mazzotta, Moscardini, Sommer-Larsen, White) - individual clusters (with hydro) - LSS structures - lensing - reionisation WG5f Source extraction and parameter estimation (Aghanim, Cayon, Lasenby) These scientific and organisational suggestions can serve as a basis for discussion in Garching. Note that simulation activity here is aimed at defining feasible scientific goals and the external datasets required to achieve them. Simulation activity is also important in understanding the impact of possible systematics on Planck Science and in defining and testing templates for component separation. Thus simulation activity must be closely interfaced both to the Systematics and to the Component Separation Working Groups. The division of activity between these groups is as yet unclear (for example, WG5f might fall more naturally under responsibility of the Component Separation WG) and must be defined by the ST as part of the overall WG structure. The Padova meeting of the Component Separation WG and this Garching meeting should together clarify this issue for the cluster/LSS area.

In order to plan for the Garching meeting it is critical for us to have an idea of the numbers of participants as soon as possible. Thus please reply to this message immediately AT THE WEB-SITE BELOW if you fall in one of the following categories;

(i) May possibly attend

(ii) Will likely attend

(iii) Will certainly attend

and tell us which category you are in! Web-site: http://planck.mpa-garching.mpg.de/register-WG.html

With best wishes,

Matthias Bartelmann, Kris Gorski, Simon White