Four decades of advances from MSDP to S4I and SLED imaging spectrometers

TL;DR

This paper reviews four decades of development in MSDP imaging spectrometers, introduces advanced versions like S4I and SLED, and discusses their applications in solar physics and dynamic solar phenomena.

Contribution

It presents a new high-resolution MSDP design called S4I and a compact SLED instrument for solar and coronal observations, enhancing capabilities for large telescopes.

Findings

S4I offers higher spectral resolution and more channels.

SLED enables dynamic studies of coronal loops and prominences.

The techniques are suitable for large telescope applications.

Abstract

The Multichannel Subtractive Double Pass (MSDP) is an imaging spectroscopy technique, which allows observations of spectral line profiles over a 2D field of view with high spatial and temporal resolution. It has been intensively used since 1977 on various spectrographs (Meudon, Pic du Midi, the German Vacuum Tower Telescope, THEMIS, Wroc{\l}aw). We summarize previous developments and describe the capabilities of a new design that has been developed at Meudon and that has higher spectral resolution and increased channel number: Spectral Sampling with Slicer for Solar Instrumentation (S4I), which can be combined with a new and fast polarimetry analysis. This new generation MSDP technique is well adapted to large telescopes. Also presented are the goals of a derived compact version of the instrument, the Solar Line Emission Dopplerometer (SLED), dedicated to dynamic studies of coronal loops observed in the forbidden iron lines, and prominences. It is designed for observing total solar eclipses, and for deployment on the Wroc{\l}aw and Lomnicky peak coronagraphs respectively for prominence and coronal observations.