ECal Invariant mass plot for day 047

 - Dataset: MuDst files from run 23047001, 23047002 with st_fwd stream

 - Gain correction: Gain correction for 1st iteration are based on the gain correction after calculating the 3rd  iteration gain correction result from day 027 test runs.

 - Event selection: (same as previous study )  1. each cluster energy > 1 GeV    2. energy asymmetry for cluster pair < 0.7    3. keep the only best cluster pair with highest pT
invariant mass plot tower by tower with fit.