Browsing by Author "Fox, J. Lewis"

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    Data inversion for the Multi‐Order Solar Extreme‐Ultraviolet Spectrograph
    (2003-11-05) Fox, J. Lewis; Kankelborg, Charles; Metcalf, Tomas R.
    The Multi­-Order Solar Extreme Ultraviolet Spectrograph (MOSES) is a high resolution, slitless imaging spectrometer that will observe the Sun in extreme ultraviolet near 304A. MOSES will fly on a NASA sounding rocket launch in spring 2004. The instrument records spatial and spectral information into images at three spectral orders. To recover the source spectrum, an ill­posed inversion must be performed on these data. We will explore two of the techniques by which this may be accomplished: Fourier backprojection and Pixons, constrained by the spatially integrated spectrum of the Sun. Both methods produce good results, including doppler shifts measured to 1/3­pixel accuracy. The Pixon code better reproduces the line widths.
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    A Transition Region Explosive Event Observed in He II with the MOSES Sounding Rocket Authors
    (2010-07-27) Fox, J. Lewis; Kankelborg, Charles; Thomas, Roger J.
    Transition region explosive events (EEs) have been observed with slit spectrographs since at least 1975, most commonly in lines of C IV (1548 Å, 1550 Å) and Si IV (1393 Å, 1402 Å). We report what we believe to be the first observation of a transition region EE in He II 304 Å. With the Multi­Order Solar EUV Spectrograph (MOSES) sounding rocket, a novel slitless imaging spectrograph, we are able to see the spatial structure of the event. We observe a bright core expelling two jets that are distinctly non­collinear, in directions that are not anti­parallel. The jets have sky­plane velocities of order 75 km s­1 and line­of­sight velocities of +75 km s­1 (blue) and ­30 km s­1 (red). The core is a region of high non­thermal Doppler broadening, characteristic of EEs, with maximal broadening 380 km s­1 FWHM. It is possible to resolve the core broadening into red and blue line­of­sight components of maximum Doppler velocities +160 km s1 and ­220 km s­1. The event lasts more than 150 s. Its properties correspond to the larger, long­lived, and more energetic EEs observed in other wavelengths.
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