Westerbork ultra-deep HI imaging of galaxy clusters at z=0.2

We report here on results from our completed ultra-deep blind HI survey of two galaxy clusters at redshift z=0.2, performed with the Westerbork Synthesis Radio Telescope. The field of the X-ray bright, massive Butcher-Oemler cluster Abell 963 was observed with a total of 117x12hrs integration time. Additionally, Abell 2192 was observed as an example of a more diffuse cluster, at similar distance, with a total of 73x12hrs integration time. In both fields, sampling a total volume of 7x10⁴ Mpc³, the expected noise levels of 19 and 24 µJy/beam respectively, at a velocity resolution of 44km/s, were achieved. These HI measurements are part of a multi-wavelength survey including ultraviolet(GALEX), optical(INT), infrared(Spitzer), and rest frame 1.4 GHz radio-continuum data(WSRT).The goal is to study the gas content of galaxies in various environments at a redshift of 0.2 and in particular the gas content of the blue galaxies that are responsible for the Butcher-Oemler effect in Abell 963.