The results of a successful survey connecting the booster ring monuments through the BTS (Booster-To-Spear) tunnel to the SPEAR tunnel are presented. Adequately surveying the BTS region is difficult due to the limited width of the tunnel and limited opening to the booster and ring. Care had to be taken in designing and processing a geometrically sound observation scheme.

The geometry was greatly enhanced by having the roof blocks over the BTS nearest the SPEAR ring removed as well as having the BL1 (Beam-Line one) plug removed. Instruments could be placed on top of the tunnel housings allowing many more observations to be obtained. Similarly, the advantage of using a station point as also a target point (forced-centering) in difficult situations, combined with free-stationing, contributes to the successful results presented below.

Note that the produced simulation is based on the actual observation scheme meaning that geometry and weighting are fully accurate.