Class Transitions and Two Component Accretion Flow in GRS 1915+105
  The light curve of the galactic micro-quasar GRS 1915+105 changes in at least thirteen different ways which are called classes. We present examples of the transitions from one class to another as observed by the IXAE instrument aboard the Indian Satellite IRS-P3. We find that the transitions are associated with changes in photon counts over a time-scale of only a few hours and they take place through unknown classes. Assuming that the transitions are caused by variation of the accretion rates, this implies that a significant fraction of the matter must be nearly freely falling in order to have such dramatic changes in such a short time. 
Sandip K. Chakrabarti, Anuj Nandi, A. K. Chatterjee, A. K. Choudhury   and U. Chatterjee