ASCA observation of G299.2-2.9

In this paper, we present the ASCA observation of supernova remnant G299.2- 2.9 for the first time and discuss its physical features by our analyses of its X-ray data. The spectrum of G299.2-2.9 is identified as a thermal plas ma emission which has already reached the ionization equilibrium. The absor bing column density obtained from the broadband spectral fitting of G299.2- 2.9 indicates its distance as 5 kpc, which is more certain than before and is in good agreement with the intermediate value given by Busser and cowork ers and that suggested by Slane and coworkers. Hence, it naturally gives a better constraint on the physical parameters of G299.2-2.9. The morphology of G299.2-2.9 is neither central filled nor normal shell type, but a shell type with an incomplete central annulus. We suggest that this special morph ology may be caused by the evaporation of the cloudlets.