BLLac was tracked (using the'map16' technique) for an hour straddling transit through the north. Plots of the residuals against azimuth are shown below (with time running from right to left) :

There are no large and significant structures (in azimuth or elevation) or steps (in elevation) that would indicate significant track model errors or transit effects, respectively. Note however, that

• the strongest excursion - that in del at az=368 - does not correspond to any track joint,
• the elevation data may be deemed to be more negative before transit (az>360) and positive afterwards, but as transit effects go, it's quite weak.

The rms scatters on the hour's worth of data are (1.1", 1.2") in (daz,del). Tracking seemingly benefits from the use of the hybrid track model.