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Return to: UVOT Digest

Image Wrap-Around Strip

There is an issue with the UVOT detector that causes data to wrap around the detector. The effect is for the highest physical column of a RAW UVOT image to wrapped around the detector to become the lowest column. This can result in false detections of sources on the left-hand edge of the detector. The wrap-around strip is one physical pixel wide (eight virtual pixels with 1x1 binning or four virtual pixels if 2x2 binning is used). The wrapped pixels are marked as cold pixels (quality flag = 4) in the UVOT bad pixel map

Figure 1: The UVOTA bad pixel map as of 2008-01-01. The location of the wrap-around strip is shown by the green stripe on the left-hand side of the detector.

Return to: UVOT Digest