WFC3 Instrument Handbook for Cycle 24 . ... Wide Field Camera 3 Instrument Handbook for Cycle 24 > Chapter 4: Designing a Phase I WFC3 Proposal > 4.2 Preparing a Phase I Proposal . ... 4.2.2 What Exposure Times? ... 4.2.5 Any Special Calibration Observations? ... The angular resolution, field of view, and sensitivity of the two channels differ appreciably, and may also influence your selection of the WFC3 channel(s) to use (see Chapter 2 for an overview of the UVIS and IR channels). ... IR Exposures . ...