Probing the Proper Motion of the Central Compact Object in Puppis-A with   the Chandra High Resolution Camera
  By making use of the sub-arcsecond angular resolution of the High Resolution Camera (HRC-I) aboard the Chandra X-ray satellite we have examined the central compact object RX J0822-4300, in the supernova remnant Puppis-A for a possible proper motion. Using data which span an epoch of 1952 days we found the position of RX J0822-4300, different by $0.574\pm0.184$ arcsec, implying a proper motion of $\mu=107.49\pm34.46$ mas/yr. For a distance of 2.2 kpc, this proper motion is equivalent to a recoil velocity of $1121.79\pm 359.60$ km/s. The position angle is found to be $241^\circ \pm 24^\circ$. Since both the magnitude and direction of the proper motion are in agreement with the birth place of RX J0822-4300, being near to the optical expansion center of the supernova remnant, the result presented in this letter is a promising indication of a fast moving compact object in a supernova remnant. Although the positional shift inferred from the current data is significant at a $\sim3\sigma$ level only, one or more future HRC-I observations can obtain a much larger positional separation and further constrain the measurement. 
C. Y. Hui and W. Becker