Recent updates in the technical design of the Maunakea Spectroscopic Explorer

The design of the Maunakea Spectroscopic Explorer (MSE) facility continues. This poster will cover some of the major areas of this effort.

The anastigmatic telescope design has been selected as the new baseline concept for MSE. Effort is underway to analyze the sensitivity of the telescope; the optimal field of view; a higher target density; and configuration of the fiber feeds and spectrographs to better enhance sensitivity performance, particularly in the blue.

The 12-meter aperture, segmented mirror telescope provides a focus at a Nasmyth platform that will provide considerably shorter fiber optic lengths than telescopes with Prime Focus or Cassegrain instrumentation. A much higher fiber density is also possible with the f/4 focus than would be viable with a Prime Focus design with upwards of 18,000 spectral probes being viable within the currently envisioned 1.5 square degree field of view (FOV).

We are currently exploring the feasibility of increasing the FOV to 2.0 square degrees and possibly 2.5 square degrees with a commensurate increase in the number of spectral probes (~24,000 probes for the 2 square degree FOV and ~30,000 probes for the 2.5 square degree FOV).

Examination is also underway for doing wavelength splitting within the fiber assembly rather than in the spectrographs. This would allow placement of the blue channels to be located very close to the Nasmyth mounted fiber positioner resulting in a much shorter fiber length. Such an arrangement should allow about a factor of two increase in the sensitivity at the bluest wavelengths of MSE.

This very high spectral probe count results in several hundred sets of spectrographs each with 3 to 5 channels. Each channel requiring its own detector and cooling system. Power demands will be significant and will require careful consideration to keep MSE sustainable and environmentally friendly.

A summary of these explorations will be presented.