Pixel Maps of Artifacts in IUE Raw Images

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Session 45 -- IUE Final Archive
Display presentation, Thursday, January 13, 9:30-6:45, Salons I/II Room (Crystal Gateway)

[45.05] Pixel Maps of Artifacts in IUE Raw Images

M.A. Fitzurka (Omitron), O. Bruegman (Omitron), D.M. Crenshaw (CSC)

We present the results of our study to find camera artifacts in IUE raw images. Artifacts are artificial emission features that appear in IUE images at long exposure times (greater than an hour) and can easily be mistaken for actual spectral emission features since they scale in time-integrated flux directly with the total background exposure level. Because these artifacts are inherent to backgrounds built up over time as a result of camera phosphorescence and not due to arbitrary events, like cosmic ray hits, these features are always present and therefore readily identifiable. To isolate and characterize these features, we collected and analyzed seven sky background images for each camera. An artifact image was constructed by determining a median value for each pixel location based on these sky backgrounds in order to obtain a representation of a generic background map. Using the median value ensured the removal of spurious data from the final images and enabled the detection of the artifacts. The pixel locations and relative intensities for 297, 281 and 362 artifacts for each of the 3 working IUE cameras, SWP, LWR, and LWP respectively, have been determined and are listed in our study.

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