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| Paper: |
Correcting for the Geometric Distortions on the COS FUV Detector |
| Volume: |
351, Astronomical Data Analysis Software and Systems XV |
| Page: |
339 |
| Authors: |
Beland, S.; Penton, S.V. |
| Abstract: |
The Hubble Space Telescope's (HST) Cosmic Origins Spectrograph (COS) Far Ultraviolet (FUV) detector consists of micro-channel plates (MCP) and time-delay anodes to provide photon counting and imaging capabilities. The COS FUV detector does not contain physical pixels, instead it uses time-delay circuits to compute the photon arrival location (in digital elements, DE). The map between the physical photon arrival position and DE is a function of the physical characteristics of the MCPs and their associated electronics. Non-linearities in this mapping are seen as geometric distortions in images taken with either of the FUV detector's two independent segments (‘A’ and ‘B’).
Repairs to the FUV detector in early 2003 affected its physical characteristics, making the initial geometric distortion correction maps unusable. A new method was developed during the October 2003 calibration phase of COS to measure the new geometric distortion correction maps and is presented here. This method uses the known spectral lines of Platinum-Neon (Pt-Ne) lamps to map the two-dimensional geometric distortions across the FUV detector. |
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