Ground-based image reduction in support of Juno |
Ground-based image reduction in support of Juno |
Dec 9 2016, 04:09 PM
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Newbie Group: Members Posts: 7 Joined: 9-December 16 From: University of Leicester Member No.: 8085 |
Hello everyone,
I am a postgraduate researcher studying the climate variability of Jupiter during the Juno mission. This involves analysis and comparison of ground-based observations taken from the Very Large Telescope (VLT) in Chile and data, to be used at a later date, from Juno, with ground-based observations corresponding with perijoves of the spacecraft. My first project has been working on reducing images taken by the VISIR mid-infrared instrument (operating range between 5 and 20 microns) on the VLT (more details found below). As a result of new AQUARIUS detector (installed 2016) on VISIR, there is a pattern that plagues all of the images. This pattern causes problems with data retrieval (getting useful information about temperature and composition of the atmosphere) and is also not very nice aesthetically and not entirely suitable for publication. The current technique for reducing this data and removing the lines works fine aesthetically, however it uses the program GiMP. This means that although it fixes the problem, it does so by smoothing or in-painting in ways that aren't truly scientific. Pixel values will be changed and information will be introduced or lost such that it actually affects the science output from the observations. I have provided the link to a public google drive folder containing some of the raw images as a sample of what we are dealing with, I can provide more if necessary. From my (limited) knowledge of programming (Python and IDL) I have been able to remove the central horizontal stripe, but the vertical stripes remain (although the images attached do not show this as they are purely raw images directly from the observatory). If anyone has experience with removing detector patterns and any pattern like this or can recommend some techniques to try it would be greatly appreciated! ESO - VISIR instrument: http://www.eso.org/sci/facilities/paranal/...ents/visir.html Google drive folder: https://drive.google.com/open?id=0B8_Ynti1o...M3hjS3dWal83X28 edit: fixed the links -------------------------------------------------------------------------------------------------- Thank you, Padraig Donnelly DISCLAIMER: All images provided are taken from the VLT in Chile and are fully credited to the European Southern Observatory (ESO). |
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Dec 9 2016, 11:52 PM
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#2
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Member Group: Members Posts: 122 Joined: 26-June 04 From: Austria Member No.: 89 |
The software "Topaz Denoise" include a debanding feature.
But if you could find the real flatfield data this should be at first used to get calibration right before you try other techniques. Robert |
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