PTSLEW is the time allowed in a pointing sequence to get to source before beginning the raster. This parameter should only be of interest to VLBA operations staff. In actual use, if a scan start time is specified, the interval between that start time and the previous stop time is added to the PTSLEW to set the duration of the slewing scan. For most pointing observations, it is probably best to set PTSLEW to something small, perhaps the same as PTDUR, and use dwell time scheduling.