High resolution Infrared Spectrograph for Exoplanet Characterization
HISPEC is a diffraction-limited, fiber-fed high-resolution infrared spectrograph covering the y to K band spectral range in one shot (0.98 to 2.46 microns). Being diffraction limited allows for a compact and stable design. HISPEC is being built for the Keck II telescope and fed by the upgraded Keck II AO system (project HAKA). HISPEC's first light at Keck Observatory is slated for 2026. HISPEC will be the workhorse high-resolution infrared spectrograph of TMT soon after first light, as part of the MODHIS facility, which includes a new fiber injection unit designed to integrate NFIRAOS the first light adaptive optics system of TMT. The scientific scope of HISPEC/MODHIS is very broad and ranges from exoplanet IR PRV, transit spectroscopy, direct spectroscopy, BD characterization, stellar physics/chemistry, disk kinematics/composition, and extragalactic science.
| Parameters | Specifications | Notes |
|---|---|---|
| Wavelength coverage | y to K (0.98 to 2.46 microns) | Simultaneous |
| Resolving power (R) | 100,000 | On average |
| Instrumental stability | 30 cm/s | Excludes atmosphere |
| Calibration | Laser Frequency Comb, Fabry-Perot Etalon | Gas cells for absolute reference |
| Design approach | Diffraction-limited | Single mode |
| Feed | Single-mode fibers, photonic lanterns | Modest multiplexing (TBD) |
| End-to-End efficiency | >5% | Goal: >10% |
| Sampling | >2.5 pixel | Over 80% of the range |
| Point Source sensitivity on Keck | 15 mag | S/N=30 per resel in 4 hours |
| Point Source sensitivity on TMT | ~19 mag | S/N=30 per resel in 4 hours |
| Mode 1 | Single or multi-object | Photonic lantern or single-mode fibers |
| Mode 2 | High-contrast off-axis | High Dispersion Coronagraphy |
| Mode 3 | High-contrast on-axis | Vortex Fiber Nulling |