|HST Primer for Cycle 25|
5.5 Spatial scan capability, available only for WFC3, facilitates cutting edge photometric and astrometric observations of very bright targets. This mode supports observations that otherwise would result in detector saturation, and it provides the potential to expand the use of WFC3 to new areas of scientific discovery. For some science applications, this mode can also result in greater scientific return using fewer HST orbits.The use of spatial scans is not permitted with coordinated or pure parallels, moving targets, and internal targets. Additionally, scan exposures may not use the optional parameter CR-SPLIT and may not have special requirements that force them to occur at the same spacecraft position as another exposure. Please see the Phase II Proposal Instructions, the WFC3 Instrument Handbook and WFC3 ISR 2012-08 for more details on this mode.