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Wide Field Camera 3 Instrument Handbookfor Cycle 23 > Chapter 2: WFC3 Instrument Description > 2.4 Detector Read-Out Modes and Dithering

2.4
The detectors in both channels offer subarray readout capability; see Section 6.4.4 (UVIS) and Section 7.4.4 (IR) for full details. The UVIS channel also allows 22 and 33 on-chip binning of full-frame images. Finally, a variety of dithering patterns can be requested using the Astronomer’s Proposal Tool (APT) software. Predefined patterns have been established to address common requirements, such as sub-pixel dithering to improve PSF sampling or dithering to achieve large areal coverage while also sampling the inter-chip gap (Appendix C:). The post-observation pipeline software (see Appendix E:, the WFC3 Data Handbook, and the AstroDrizzle documentation) carries out appropriate calibration of data taken in all of these configurations, and offers the option of reconstructing dithered images with a drizzling algorithm. A combination of software packages in DrizzlePac can be used to optimize the drizzling of images. If the dither pattern incorporates non-integer pixel offsets, it can effectively improve the sampling of the point-spread function (PSF). The software can also handle mosaicked images according to a set of rules or associations, rectifying them onto a cartesian pixel coordinate system.

Wide Field Camera 3 Instrument Handbookfor Cycle 23 > Chapter 2: WFC3 Instrument Description > 2.4 Detector Read-Out Modes and Dithering

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