void leaf_test2(string filename){
    
  TChain *chain = new TChain("tevent_2nd_integral");
  chain->Add(filename.c_str());
  int nframes = chain->GetEntries();
 
  int bins = 48;

  float counts_data[1][1][bins][bins];
  chain->SetBranchAddress("photon_count_data", counts_data);
  
  uint gtu=0;
  chain->SetBranchAddress("gtu", &gtu);
  
  double xlat = 0;
  double xlon = 0;
   
  TBranch *positionISS = (TBranch*)chain->GetBranch("positionISS");
  TLeafD *llat=(TLeafD*)positionISS->GetLeaf("lat");
  llat->SetAddress(&xlat);
  
  TLeafD *llon=(TLeafD*)positionISS->GetLeaf("lon");
  llon->SetAddress(&xlon); 
   
  for(int igtu=0; igtu<nframes; igtu++){
    chain->GetEntry(igtu);
    
    cout <<" gtu=" <<gtu <<endl; //works
    cout <<" xlat=" <<xlat <<" xlon=" <<xlon <<endl; //does not work
  }  
}