Browsing by Author "Parker, Jacob D."

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Determining the Spectral Content of MOSES Images
(American Astronomical Society, 2022-06) Parker, Jacob D.; Kankelborg, Charles C
The Multi-Order Solar Extreme Ultraviolet Spectrograph (MOSES) sounding rocket was launched from White Sands Missile Range on 2006 February 8th, to capture images of the Sun in the He ii 303.8 Å emission line. MOSES is a slitless spectrograph that forms images in multiple spectral orders simultaneously using a concave diffraction grating in an effort to measure line profiles over a wide field of view from a single exposure. Early work on MOSES data showed evidence of solar features composed of neither He ii 303.8 Å nor the nearby Si xi 303.3 Å spectral lines. We have built a forward model that uses cotemporal EIT images and the Chianti atomic database to fit synthetic images with known spectra to the MOSES data in order to quantify this additional spectral content. Our fit reveals a host of dim lines that alone are insignificant but combined contribute a comparable intensity to MOSES images as Si xi 303.3 Å. In total, lines other than He ii 303.8 Å and Si xi 303.3 Å contribute approximately 10% of the total intensity in the MOSES zero order image. This additional content, if not properly accounted for, could significantly impact the analysis of MOSES and similar slitless spectrograph data, especially those using a zero-order (undispersed) image. More broadly, this serves as a reminder that multilayer EUV imagers are sensitive to a host of weak contaminant lines.
First Flight of the EUV Snapshot Imaging Spectrograph (ESIS)
(American Astronomical Society, 2022-10) Parker, Jacob D.; Smart, Roy T.; Kankelborg, Charles; Winebarger, Amy; Goldsworth, Nelson
The Extreme-ultraviolet Snapshot Imaging Spectrograph (ESIS) launched on a sounding rocket from White Sands Missile Range on 2019 September 30. ESIS is a computed tomography imaging spectrograph (CTIS) designed to map emission line profiles across a wide field of view, revealing the structure and dynamics of small-scale transient events that are prevalent at transition region temperatures. In this paper, we review the ESIS instrument, mission, and data captured. We demonstrate how this unique data set can be interpreted qualitatively and further present some initial quantitative inversions of the data. Using a multiplicative algebraic reconstruction technique, we combine information from all four ESIS channels into a single spatial–spectral cube at every exposure. We analyze two small explosive events in the O v 629.7 Å spectral line with jets near ±100 km s−1 that evolve on 10 s timescales and vary significantly over small spatial scales. Intriguingly, each of these events turns out to be a bimodal (red+blue) jet with outflows that are asymmetric and unsynchronized. We also present a qualitative analysis of a small jetlike eruption captured by ESIS and draw comparisons to previously observed mini-filament eruptions. In 5 minutes of observing time, ESIS captured the spatial and temporal evolution of tens of these small events across the ∼11.′5 field of view, as well as several larger extended eruptions, demonstrating the advantage of CTIS instruments over traditional slit spectrographs in capturing the spatial and spectral information of dynamic solar features across large fields of view.