The National Astronomical Observatory of Japan (NAOJ) has been operating large astronomical facilities, such as Subaru, radio telescopes at Nobeyama, Hinode, for the benefit of astonomical communities. These facilicites have produced large amount of observed data, around one Peta bytes or so, which are archived in databases and are published online. Further HyperSuprimeCAM equipped with Subaru will produce ten times larger amount of data than before, and the ALMA will produce a few hundreds of Terabytes per year.
Thus NAOJ has decided to collect all the observed data to the Astronomy Data Center, NAOJ, from where the data is published through traditional ways and vitual observatory. This will enable astronomers to easily conduct, e.g. to generate Spetcrum Energy Distribution (SED) in a wide wavelength range, to compare images in different wavelength; all these procedures are essential in understanding astronomical phenomena