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 mu m at a spectral resolution of R 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 similar to 10 ms(-1) rms over a period of several hours. The most recent instrument configuration has achieved an unbinned rms of 7 ms(-1) and suggests that infrared radial velocity precisions may be able to approach those achieved at optical wavelengths.