Probing the spectral-temporal states of bright ULXs at different flux levels

We request three 70ks observations of the bright ULX Holmberg II X1, separatedby 25 months. We also request two 120ks observations, separated by 26 months,of another bright ULX Holmberg IX X1, thus making a total of 450ks exposure.The primary purpose of these observations is to measure the broad band noisepower density spectra (PDS) and Xray spectral shapes at different flux levels.The existing long observations have provided PDS and Xray spectra at singleepochs and suggest that both these ULXs are likely in the strongly Comptonizedvery high states. The proposed observations will allow us to define spectralstates of ULXs at different flux levels, and make a definitive analogy betweenspectral states of ULXs and the well studied Galactic black hole Xray binaries (BHBs). truncated!, Please see actual data for full text [truncated!, Please see actual data for full text]