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We discovered kHz QPOs in 80 archived RXTE observations from the peculiarlow-mass X-ray binary (LMXB) Circinus X-1. In 11 cases these appear in pairs inthe frequency range of ~230 Hz to ~500 Hz for the upper kHz QPO and ~56 Hz to~225 Hz for the lower kHz QPO. Their correlation with each other, which issimilar to that of frequencies of kHz QPO pairs in other LMXBs containing aneutron star, and their variation by a factor two confirm that the centralobject is a neutron star. These are the lowest frequencies of kHz QPO pairsdiscovered so far and extend the above correlation over a frequency range offactor four. In this new frequency range the frequency difference of the twokHz QPOs increases monotonically by more than ~170 Hz with increasing kHz QPOfrequency, challenging theoretical models.Comment: 3 pages, 2 figures - one from astro-ph/0608089 (ApJ 653, 1435, 2006)  in corrected form, to appear in the proceedings of the 11th Marcel Grossman  meeting, improved wording, added referenc

kHz QPO PAIRS EXPOSE THE NEUTRON STAR OF CIRCINUS X-1