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Self-Calibration

If you have sufficient signal-to-noise on your target source or any source in the field, then you may now use the calibrater tool to improve the dynamic range of your images. This improved calibration or "self-calibration" technique assumes that your images have been degraded by complex gain errors which vary too rapidly with time or direction to have been fully calibrated with the calibrator sources. The calibrater tool compares the observed uv DATA with a model of the data that you created during the initial CLEANing and determines amplitude and/or phase corrections which bring the CORRECTED_DATA into better agreement with the model.

Do not self-calibrate unless your target source has enough signal-to-noise to warrant improvement. Ask yourself whether your externally-calibrated CLEAN images contain artifacts well above the noise. If so, self-calibration may improve the image. If your images are limited by system noise, self-calibration may produce erroneous results, including the fabrication of weak sources!

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