Multi-order slitless solar spectroscopy: a parametric inversion approach

2012-08-16
Öktem, Sevinç Figen
Kamalabadi, Farzad
Davila, Joseph M
Spectrographs provide measurements of emission line parameters, which are essential for extracting the plasma parameters and understanding the dynamic solar atmosphere. However, spectral observations of multiple spatial dimensions with inherently two-dimensional detectors pose intrinsic limitations on the spatio-temporal extent of the technique. A common observation strategy, based on conventional slit spectrographs, is to use a narrow field-of-view and a time-consuming rastering process, hence limiting the spectroscopic analysis of dynamic events. An alternative strategy is to use a slot spectrograph by widening the slit; however the dispersion within the wide slot image is the bottleneck. Recently the concept of multi-order slitless spectroscopy has been developed to address these limitations. Based on a parametric model for the formation of dispersed images, we study the problem of estimating emission line parameters from the slitless spectrometer measurements. This inverse problem can be viewed as a multiframe deblurring problem with shift-variant blur, where multiple blurred images of the same object are obtained through multiple spectrometer measurements, each with a different diffraction order. We approach the solution of this problem based on an iterative parametric inversion technique with regularization. The new deblurring method provides significantly more accurate intensity, Doppler shift, and line widths over a large spatial region on the Sun. We also perform sensitivity analysis using the Cramer-Rao framework, which yields insights about instrument optimization. The development of optimized multi-order slitless spectrographs and reliable inversion algorithms will yield reconstruction of spectral line parameters at every pixel over the large FOV, and faciliate the understanding of highly dynamic solar events such as flares, CMEs, and transient brightening.
Citation Formats
S. F. Öktem, F. Kamalabadi, and J. M. Davila, “Multi-order slitless solar spectroscopy: a parametric inversion approach,” Bozeman, USA, 2012, p. 43, Accessed: 00, 2021. [Online]. Available: http://www.sipwork.org/v1/wp-content/uploads/2012/08/SIPWork6_full_booklet_v3.pdf.