I followed the directions at: drupal.star.bnl.gov/STAR/blog/rjreed/tac-offset-files-epd

To start with, we were using the TAC Offset values from Run 20.  This resulted in the following trigger distribution.

Figure 1: TAC distributions for the EPD for run 22069040 and the associated vertex XY position.

The timing settings for this run are:
EPD_QTc_W_TAC_Max    2750   
EPD_QTc_W_TAC_Min    300   
EPD_QTc_E_TAC_Max    2750   
EPD_QTc_E_TAC_Min    300
EPD_TACdiff_max        4928   
EPD_TACdiff_min        3262

The EPD makes up 99% of the minbias-hlt70 trigger (though it should be noted that the vpd is 70%). 

Ideally what we would see is a single bright spot that is about the same TAC East as TAC West.  We don't see that there.....  Instead there are the two bright spots on either side of the edge - and it's not clear what we are looking at here.  Beam satelites perhaps?  But it is clear that most events in this sample are good gold-gold events - so why is the distribution so strange looking?