First Meeting (September 28, October 2, 2015). The aim of the first meeting has been to discuss the results obtained and future work: here only 3D or 3D+t codes were considered, because we focus on understanding the circumnuclear coma (distance <50km from the surface). At the end of 2014, all the data usable to describe the 67P nucleus activity beyond a sun-distance of 2AU were available. It is foreseen that the most straightforward data able to constrain the 3D+t models will be in-situ gas mass spectra of ROSINA and the dust (optical continuum) OSIRIS images. Work is in progress regarding a satisfactory modeling of radiative transfer in a 3D gas coma and of highly non-equilibrium gas condition near nucleus to evaluate line excitation by the gas. After these goals will be reached, also water images at mmwavelengths could become model input. Additional critical information are the dust grain mass and cross section spectra and individual grain velocities measured in-situ by GIADA. The goal of this meeting has been a critical review of the status of data/model results best-fits, and a critical review of the resulting inferred nucleus activity properties. Minutes of the meeting are available here.

Second meeting (Spring 2016). The heliocentric variation of the above-mentioned activity model will be discussed. This may imply also deducing outer coma and dust tail properties and thus evaluating the accuracy of what the currently used 1D or 2D model predict. If so, the team will have to be enlarged a little to welcome one or two scientists using currently such 1D/2D models, and one or two representatives of the optical instruments MIRO and VIRTIS. Third meeting (2016, after ISSI approval given the high number of core members) The same as the second meeting, but now one will compare the “activity increase” profile with the “activity decrease” profile.