A pathfinder instrument for precision radial velocities in the near-infrared

We have designed and tested an in-plane echelle spectrograph configured to investigate precision radial velocities from ground-based near-infrared observations. The spectrograph operates across the spectral range of 0.9–1.7 μm at a spectral resolution of R ¼ 50; 000, and uses a liquid nitrogen-cooled HAWAII 1 K detector. Repeated measurements of the Earth’s rotation via integrated sunlight with two different instrument arrangements in the near-infrared Y band have produced radial velocities with ∼10 ms1 rms over a period of several hours. The most recent instrument configuration has achieved an unbinned rms of 7 ms1 and suggests that infrared radial velocity precisions may be able to approach those achieved at optical wavelengths.