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Linearity Analysis and Efficiency Testing of The Chromospheric Lyman-Alpha Spectro-Polarimeter (CLASP) Science Cameras for Flight
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Author and Affiliation:
Walker, Salma C.(California State Univ., Northridge, CA, United States)
Rachmeler, Laurel(NASA Marshall Space Flight Center, Huntsville, AL, United States)
Winebarger, Amy(NASA Marshall Space Flight Center, Huntsville, AL, United States)
Champey, Patrick(NASA Marshall Space Flight Center, Huntsville, AL, United States)
Bethge, Christian(Universities Space Research Association, Huntsville, AL, United States)
Abstract: To unveil the complexity of the solar atmosphere, measurement of the magnetic field in the upper chromosphere and transition region is fundamentally important, as this is where the forces transition from plasma to magnetic field dominated. Measurements of the field are also needed to elucidate the energy transport from the lower atmospheric regions to the corona beyond. Such an advance in heliospheric knowledge became possible with the first flight of the international solar sounding rocket mission, CLASP. For the first time, linear polarization was measured in Hydrogen Lyman-Alpha at 121.60 nm in September 2015. For linear polarization measurements in this emission line, high sensitivity is required due to the relatively weak polarization signal compared to the intensity. To achieve this high sensitivity, a low-noise sensor is required with good knowledge of its characterization, including linearity. This work presents further refinement of the linearity characterization of the cameras flown in 2015. We compared the current from a photodiode in the light path to the digital response of the detectors. Pre-flight CCD linearity measurements were taken for all three flight cameras and calculations of the linear fits and residuals were performed. However, the previous calculations included a smearing pattern and a digital saturation region on the detectors which were not properly taken into account. The calculations have been adjusted and were repeated for manually chosen sub-regions on the detectors that were found not to be affected. We present a brief overview of the instrument, the calibration data and procedures, and a comparison of the old and new linearity results. The CLASP cameras will be reused for the successor mission, CLASP2, which will measure the Magnesium II h & k emission lines between 279.45 nm and 280.35 nm. The new approach will help to better prepare for and to improve the camera characterization for CLASP2.
Publication Date: Dec 11, 2017
Document ID:
20170011703
(Acquired Dec 14, 2017)
Subject Category: SOLAR PHYSICS
Report/Patent Number: MSFC-E-DAA-TN49423
Document Type: Oral/Visual Presentation
Meeting Information: AGU Fall Meeting; 11-15 Dec. 2017; New Orleans, LA; United States
Meeting Sponsor: American Geophysical Union; Washington, DC, United States
Contract/Grant/Task Num: 80MSFC17M0022; NSF-AGS-1460767
Financial Sponsor: NASA Marshall Space Flight Center; Huntsville, AL, United States
Organization Source: NASA Marshall Space Flight Center; Huntsville, AL, United States
Description: 1p; In English
Distribution Limits: Unclassified; Publicly available; Unlimited
Rights: Copyright; Portions of the document may include copyright protected material
NASA Terms: LINEAR POLARIZATION; LYMAN ALPHA RADIATION; CHROMOSPHERE; MAGNETIC FIELDS; CAMERAS; LINEARITY; CHARACTERIZATION; SENSITIVITY; SOUNDING ROCKETS; POLARIMETERS; MEASURING INSTRUMENTS; PHOTODIODES
Other Descriptors: CCD; DETECTOR; LINEARIT
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