Recently, it was noticed that when comparing a picture of the FC1 HSTS to the SolidWorks model, an ~0.97" (~24.6mm) difference in y-axis position was noticed; FC1 looked farther in +Y than it should have been (see attached picture).  In an effort to try to find the source of the error, I rechecked all of my alignment solution calculations.  Fortunately (or unfortunately, depending on one's point of view), I did find an 18mm error in my calculations.  It's a stupid one, too.  When writing down the coordinates for our alignment monument, LV37, I transposed the ones and tens digits for the y-axis coordinate; in subsequent checks of my math (this is check number 4...), I failed to notice that I had done this.  As a result, I used a y-axis coordinate for LV37 of -4986.4mm instead of -4968.4mm, causing an 18mm error that followed through the entire alignment solution calculation.  In essence, this caused us to shoot the wrong distance with the total station's Electronic Distance Measurement (EDM) function when setting FC1 y-axis position; instead of being too long by 1.6mm, FC1 is actually too short by 16.4mm.  This also caused a very small (0.1mm) error in FC1 vertical position (total station at wrong height), but no change in x-axis position, pitch, or yaw.  Now that this has been found, I've corrected the as-built alignment numbers for FC1 to account for this error (this supplants the as-built numbers reported in alog 60810):

There is still ~8.2mm of error that are unaccounted for, as my mistake only has us short by 16.4mm, not the entire 24.6mm identified in the attached photo (the photo is approximate).  Investigations are currently underway to see if we can live with this error or not.  I offer my sincerest apologies, this is a stupid mistake that should have been caught much sooner.