Visible Multi-Object Spectrograph – GMACS


The GMT visible multi-object spectrograph (GMACS) covers a relatively wide field and uses wavelength multiplexing to deliver a large AΩ-λ combination. Dichroic mirrors feed cameras optimized over single octave bandpasses. The full instrument will deliver moderate resolution (R =1500 – 5000) spectroscopy over a large field of view from the near UV to very near-IR regions of the spectrum. The GMACS team is refining the concept for the instrument and considering trades between field of view, wavelength coverage, resolution and operating modes. The concept shown above, with two spatial and two wavelength channels, has been developed by a team at Texas A&M and Carnegie as part of the early conceptual design.

PI: Darren DePoy (Texas A&M)

Science Goals

Distant galaxies – Lyα luminosity function at z < 6.5, chemical enrichment of ISM, redshift surveys
Nearby galaxies – chemical enrichment history, dark matter distribution, stellar populations and evolution, transient follow-up

Technical Specifications

Spectral resolution: 1,000 – 6,000
Field of view: 30 – 50 arcmin2
Wavelength range: 3500 – 9500 Å
Multi-slit mask count: 24 masks with 50-100 slits/mask
Alternate input: 100s of fibers using MANIFEST
Field of view (MANIFEST): 300 arcmin2


SPIE Proc 8446-058. DePoy D. L. et al.