LOFAR: opening a new window on low frequency radio astronomy

This contribution reports on the status of LOFAR (the LOw Frequency ARray) in its ongoing commissioning phase. The purpose is to illustrate the progress that is being made, often on a daily basis, and the potential of this new instrument, which is the first "next-generation" radio telescope. Utilizing a novel phased-array design, LOFAR is optimized for the largely unexplored low frequency range: 10 240MHz. The construction of LOFAR in the Netherlands is almost complete and 8 international stations have already been deployed as well. The wide field-of-view and multi-beam capabilities, in combination with sub-milliJansky sensitivity at arcsec (and sub-arcsec) resolution, are unprecedented at these frequencies. With the commissioning of LOFAR in full swing, we report some of the initial results, in particular those coming from the testing of imaging and pulsar modes. 1. LOFAR in a nutshell LOFAR is a next-generation radio telescope operated by ASTRON and constructed in the north of the Netherlands, with extensions across Europe. Utilizing a novel phased-array design, LOFAR is optimized for the largely unexplored low frequency range from 10 to 240MHz. In the Netherlands, a total of 40 LOFAR stations are nearing completion with an initial 8 international stations also deployed. LOFAR has been described elsewhere in detail (see, e.g., (11),(4)). Here, we briefly summarize the characteristics and the status of the