Future Gemini Instrumentation

The “Aspen process” for determining the next generation of instrumentation for the Gemini telescopes continues to move ahead. A very successful meeting of approximately 100 participants from the Gemini partnership was held in June 2004 in Aspen (see Harvey Richer’s article in the September Equinox edition). Following Aspen, order of magnitude costs were developed for a short list of eight instrument capabilities, and a strong science case document (“Scientific Horizons at the Gemini Observatory: Exploring A Universe of Matter, Energy and Life”) was prepared. This information was discussed by the Gemini Science Committee (GSC) at their October meeting in La Serena, Chile.

The GSC developed a prioritized list of scientific capabilities that was forwarded to the Gemini Board for consideration at their November meeting in Hilo, Hawaii. Unlike the previous generation of Gemini instruments, there is no fixed instrumentation budget in place. The Gemini partnership will need to generate the funds for these new instruments. The Board feels that the more exciting the science the more money they can raise. The Gemini Board approved a proposal at the meeting to take the first steps in developing a new set of "Aspen instruments". Overall their recommendation is consistent with the GSC recommendation. Though it is impossible to build all of the potential new instruments identified at the Aspen meeting, the following instruments, with an approximate- total cost of ~$70M, will enable the most broadly supported science missions discussed in Aspen. The core instrumentation identified includes:

Extreme AO Coronagraph

Wavelength Range: 0.9 - 2.5 µm

Field of View: ~3 arcsec

Spatial Sampling: 0.02" IFU sampling or 0.01" imaging

Spectral Resolution: 30-300

1-shot wavelength coverage: J, H, or K

Comments: For use as either an IFU or direct multi-band imaging (e.g., dual channel). Both approaches should be among the design options considered. A contrast ratio of ~10⁷ within a 0.1-1.5" radius of the central target is needed to meet this instrument's science objectives. The instrument should also include a polarimetry mode, noting the availability of the facility polarization unit GPOL for design study purposes.

High Resolution Near-infrared Spectrograph

Wavelength Range: 1.1 - 5.0 µm

Field of View: 2 arcmin

Spectral Resolution: 70,000 (single slit) and 30,000 (MOS)

Spatial Sampling: 0.2" pixels (seeing limited mode) or 0.05" pixels (MCAO-MOS mode)

Primary Modes:

·        Single slit cross-dispersed seeing limited spectrometer with R ~ 70,000 spectral resolution and providing 1-shot wavelength coverage of as much of the J+H+K or L+M windows as possible.

·        Multi-object MCAO fed cross dispersed spectrometer sampling targets across a 2 arcmin field with ~3 arcsec long slits and R ~ 30,000 spectral resolution. The 1-shot wavelength coverage should balance against detector format, science applications, number of targets in the field, etc. Capable of recording simultaneous spectra of at least 15 targets at a time (30 goal).

Comments: Spectrometer includes a polarimetry mode, noting the availability of the facility polarization unit GPOL for design study purposes. Also includes an absorption cell to be used as a precision wavelength fiducial in the R~70,000 mode.

Wide Field Fiber Fed Optical Multi-object Spectrometer                          

Wavelength Range: 0.39 -1.0 µm

Field of View: ~1.5 deg

Spectral Resolution: R ~ 1000 - 30,000

Spatial Sampling: ~1 arcsec fiber entrance

1-shot wavelength coverage: 0.4 µm (lowest resolution mode)

Simultaneous stellar targets: 4000-5000

Comments: Fiber fed prime focus instrument capable of enormous multiplex gains by independently positioning fibers across a large prime focus field on Gemini. This instrument is similar to the KAOS concept (http://www.noao.edu/kaos/).

In addition Gemini will be funding feasibility studies in Ground Layer Adaptive Optic (GLAO) systems that might be used on Gemini. Though not identified by the GSC as part of the core Aspen instrument set (above), in the event the cost or complexity of the core instrument set becomes too great to pursue, a GLAO system (including an imager and/or dIFU spectrometer) may be pursued instead

Consistent with the above summary of new instruments, Announcements of Opportunities will soon be available for the following development work: