Data Reduction Frequently Asked Questions
My data shows an extended, bright feature - what can this be?
It is likely that some reflections from the moon are affecting your data. These reflections are unpredictable and have been found to be more frequent when the target is closer than ~40deg to the bright moon. You might also want to check http://www.eso.org/sci/observing/PublicSurveys/useful_links/OmegaCAM_images.html where we provide a collection of example OmegaCAM images, illustrating some special data features.
A comprehensive description of features visible in OmegaCAM detectors can also be found in the quality control web pages.