Browsing by Author "Kankelborg, Charles C."

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Blind technique for point spread function equalization with application to the Multi-Order Solar Extreme Ultraviolet Spectrograph
(2018-05) Atwood, Shane; Kankelborg, Charles C.
When combining remote sensing data from multiple instruments or multiple imaging channels, differences in point spread function (PSF) can lead to systematic error. If the PSFs are not well known, then it is difficult to determine which differences in the image data are meaningful for the object being observed and which are artifacts of PSF. Direct PSF measurements can be problematic. For example, in a sounding rocket payload, launch vibrations and acceleration, subsequent operations in micro gravity, and the impact on return to Earth may all affect PSFs. We have developed a blind method to equalize the PSFs of three distinct instrument channels, as found in the Multi-Order Solar Extreme Ultraviolet Spectrograph (MOSES). To validate our technique, we generate three synthetic images with three different PSFs, with some spectrally interesting features. Thence, we demonstrate the successful removal of PSF-induced artifacts is possible, with the genuine spectral features left intact. We also perform blind PSF equalizations on three copies of the same solar image, but with differing PSFs, after applying independent noise to each. The results accurately reproduce corrections performed in the absence of noise, with full knowledge of the PSFs. Finally, we apply PSF equalization to solar images obtained in the 2006 MOSES flight and demonstrate the removal of artifacts.
Design for a portable calibration system for the Full-sun UV Rocket SpecTrometer instrument
(2021-09) Vigil, Genevieve D.; Winebarger, Amy R.; Rachmeler, Laurel A.; Donders, Nicolas; Athiray, P. Subramania; Kobayashi, Ken; Kankelborg, Charles C.
The Full-sun Ultraviolet Rocket SpecTrograph (FURST) is a sounding rocket designed to acquire the first full-disk integrated high resolution vacuum ultraviolet (VUV) spectra of the Sun. The data enable analysis of the Sun comparable to stellar spectra measured by astronomical instruments such as those on board the Hubble Space Telescope. The mission is jointly operated by teams at Montana State University (MSU), developing the instrument, and Marshall Space Flight Center (MSFC), developing the camera and calibration systems, and is scheduled to launch from White Sands Missile Range, New Mexico, in 2022. This mission requires the development of a pre- and post-launch calibration plan for absolute radiometric and wavelength calibration to reliably generate Hubble analogue spectra. Absolute radiometric calibration, though initially planned to be performed at the National Institute for Standards and Technology (NIST) calibration facilities, is now planned to be completed with a portable VUV calibration system provided by MSFC, due to instrument incompatibilities with NIST infrastructure. The portable calibration system is developed to provide absolute wavelength calibration and track changes in calibration over the duration of the mission. The portable calibration system is composed mainly of a VUV collimator equipped with an extreme ultraviolet line source and calibrated photodiodes. The calibration system is developed to accommodate both repeatable wavelength and radiometric testing of the FURST instrument at various test sites before and after launch. Presented here are the requirements, design, and implementation of this portable calibration system with a focus on those features most significant to radiometric measurements.
An on Orbit Determination of Point Spread Functions for the Interface Region Imaging Spectrograph.
(2018-09) Kankelborg, Charles C.; Courrier, Hans T.; De Pontieu, Bart; Wülser, Jean-Pierre
Decades of research into the Bacteria and Archaea living in geothermal spring ecosystems have yielded great insight into the diversity of life and organismal adaptations to extreme environmental conditions. Surprisingly, while microbial eukaryotes (protists) are also ubiquitous in many environments, their diversity across geothermal springs has mostly been ignored. We used high-throughput sequencing to illuminate the diversity and structure of microbial eukaryotic communities found in 160 geothermal springs with broad ranges in temperature and pH across the Taupō Volcanic Zone in New Zealand. Protistan communities were moderately predictable in composition and varied most strongly across gradients in pH and temperature. Moreover, this variation mirrored patterns observed for bacterial and archaeal communities across the same spring samples, highlighting that there are similar ecological constraints across the tree of life. While extreme pH values were associated with declining protist diversity, high temperature springs harbored substantial amounts of protist diversity. Although protists are often overlooked in geothermal springs and other extreme environments, our results indicate that such environments can host distinct and diverse protistan communities.
Using local correlation tracking to recover solar spectral information from a slitless spectrograph
(2018-01) Courrier, Hans T.; Kankelborg, Charles C.
The Multi-Order Solar EUV Spectrograph (MOSES) is a sounding rocket instrument that utilizes a concave spherical diffraction rating to form simultaneous images in the diffraction orders m=0, +1, and -1. MOSES is designed to capture high-resolution cotemporal spectral and spatial information of solar features over a large two-dimensional field of view. Our goal is to estimate the Doppler shift as a function of position for every MOSES exposure. Since the instrument is designed to operate without an entrance slit, this requires disentangling overlapping spectral and spatial information in the m=Â±1 images. Dispersion in these images leads to a field-dependent displacement that is proportional to Doppler shift. We identify these Doppler shift-induced displacements for the single bright emission line in the instrument passband by comparing images from each spectral order. We demonstrate the use of local correlation tracking as a means to quantify these differences between a pair of cotemporal image orders. The resulting vector displacement field is interpreted as a measurement of the Doppler shift. Since three image orders are available, we generate three Doppler maps from each exposure. These may be compared to produce an error estimate.