Deep imaging of a sample of X-ray galaxy clusters in Hydra

scientific abstract: to link the survey of distant clusters to the virgo sample, we will study the midir emission of a sample of clusters in the hydra region. these clusters have been studied in the x ray range with rosat, and in the optical and radio ranges from ground, by m. pierre and coworkers. present results indicate that the correlation amongst the three wavelengths appear stronger for the higher redshift members of the sample, indicating a luminosity selection effect or, possibly, an evolution in cluster properties with redshift. observation summary: we intend to observe these clusters in the isocam filters used in the deep survey and the distant cluster proposal, lw2 and lw3, and with phot c100 at 90 microns. for clusters at z virgul 0.1, we will use aot1 in the microscanning mode, with a pfov of 6, to cover a field of 10.x10.. the objective is to detect a galaxy 10 times fainter than the starburst galaxy ngc6240 at z 0.1 (0.5 mjy at 7 microns and 1 mjy at 14 microns), with a s/n ratio of 4. we intend to perform raster scans of 8x8 positions, displacing every time the array by 16 pixels. the axis of the raster will be aligned to the spacecraft axis. the time required is 2500 seconds per filter, including all overheads. redshifting the same starburst galaxy at z0.2, intensities will be 0.1 and 0.2 mjy at 7 and 14 microns respectively. at z0.3 they will be reduced by a factor of two (i.e. 0.05 and 0.1 mjy). for clusters at zvirgul0.20.3, we shall use the following microscanning mode: 4x4 positions, displacement of 16 pixels. the area most covered will be close to 5.x5.; the total observed area will be 2.8 times larger. according to the isocam software simulator, we should obtain with lw2 in 2500 sec a s/n of 3.7 for a 0.1 mjy source; with lw3 barely >1 for a 0.2 mjy source. with flux densities two times fainter and same exposure times, the simulations show that the s/n will be decreased to virg trunc [truncated!, Please see actual data for full text]