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An ultraviolet micromirror spectrograph (UMIS) for enhanced science return

Presentation #319.04 in the session Future Missions, Instrumentations and Facilities - Part 2 (Oral Presentation)

Published onOct 23, 2023
An ultraviolet micromirror spectrograph (UMIS) for enhanced science return

We present a Far-UV imaging spectrograph instrument concept that utilizes a light directing array (LDA) to act as a dynamic image slicer. This instrument concept is funded under the MatISSE program to advance a prototype utilizing high heritage hardware to TRL 6. Each micromirror in the LDA acts as an individual spatial element that can be sent to either a broadband imaging channel or a moderate resolution spectrograph channel. This enables autonomous high dynamic range FUV spectroscopy aimed at maximizing the signal to noise ratio in each data cube.

The micromirrors in the LDA enable a type of extended source FUV emission survey that is unique in its capability, to optimize science data return and extend the dynamic range of an FUV spectrograph. The default “un-tilted” position for the micromirrors reflects the 3° x 3° image plane to a fold mirror and then onto an unused corner of the same detector that the spectra are also imaged onto. This image has 1.8 arcminute resolution over 100 x 100 resolution elements and spans a bandpass of 125 – 200 nm. This broadband emission is used to determine the relative brightness of all the 20 x 20 spatial elements (micromirrors) in the scene, to identify the brightest objects for spectroscopy. For cases where this mode is active (as opposed to a predetermined target selection), the LDA elements corresponding to the identified targets are then angled to a chosen grating, with the observing time for each object allocated to maximize overall SNR and minimize observing time. With this unique mode, bright objects can be observed briefly, and the mirror elements re-allocated to new targets, while diffuse emission can be integrated for long uninterrupted periods.

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