21CMA 21 Centimeter Array a.k.a. PAST Reionization 21cm: hyperfine transition of neutral Hydrogen 21CMA a.k.a. PAST Basic ideas: an experiment, not an observatory use cheap, off-the -shelf technology (i.e. TV+PC) simple design (looking at NCP) choose site with minimal EM interference to become operational before MWA/LOFAR Xiang-Ping Wu (NAOC) Ue-Li Pen (CITA) Jeff Peterson (Carnegie) VLBI Map of 21CMA site 21CMA E N Urumuqi Ulastai Log-Periodic antenna 20m A pod (127 antenna) correlator arrayLNAfilteramplifier Optical transmitter Opt. fibre Optical receiver ADC 21CMA data collection system Basic Design of 21CMRA At z=9, 10 comoving Mpc ~ 0.6 MHz, ~ 3.6 arcmin frequency range MHz (6.1