Commissioning and on-sky performance verification of iLocater

arXiv:2607.27332 · astro-ph.IM, astro-ph.EP, astro-ph.SR · Submitted 2026-07-29 · Read on arXiv

Marshall C. Johnson, Marcelo Tala Pinto, Jonathan Crass, Brian Sands, Jackson Datkuliak, Sai Vidyud Senthil Nathan, Justin R. Crepp, Michael Engelman, Daniel Pappalardo, Julia Brady, Mark Derwent, Xavier Lesley-Saldaña, Andrew Bechter, Eric Bechter, Christian Schwab, David Aikens, Chad Bender, Chris Brandon, Cynthia Brooks, Matheus J. Castro, Jeffrey Chilcote, Al Conrad, Gregory Delo, Erin Duell, Matthew Engstrom, Steve Ertel, Louis Fantano, John Keith Feggans, Hali Flores, B. Scott Gaudi, David King, Ondrej Kitzler, Kaitlin M. Kratter, Jeffrey Kruk, Thomas Legero, Stanimir Letchev, Jerry Mason, Joaquin Mason, Matthew Misch, Jacob Pember, Richard Pogge, Andreas Quirrenbach, Joshua Schlieder, Augustyn Waczynski, Joseph Shields, Daewook Kim, Mark Smithwright, Allie Renshaw, Austin Richie, Alexa Rizika, Nandini Sadagopan, Jonathan Shover, James Smous, Jayde Spiegel, Julian Stürmer, Sahil Sura, Robert Switzer, Joe Thomes, Ji Wang, Lauren Weiss, Daniel Wilson, Dane Zielinski-Nicolson

astro-ph.IM, astro-ph.EP, astro-ph.SR

Submitted: 2026-07-29

Comments: Submitted to SPIE Astronomical Telescopes + Instrumentation 2026, Paper 14149-195. 12 figures, 4 pages

License: http://creativecommons.org/licenses/by/4.0/

The gist: iLocater is a high-resolution near-infrared extreme precision radial velocity (EPRV) spectrograph that was deployed to the Large Binocular Telescope (LBT) in June 2026.

Terminology

Abstract

iLocater is a high-resolution near-infrared extreme precision radial velocity (EPRV) spectrograph that was deployed to the Large Binocular Telescope (LBT) in June 2026. iLocater operates over lambda=966-1312 nm with a median resolving power of R=205,000 as measured in the laboratory. We present the commissioning and initial on-sky verification program using solar and night-time observations at the LBT. First light was achieved on 27 June 2026, and nearly 150 on-sky spectra have now been recorded. Observations include single stars ranging in spectral type from B5 to M6. iLocater uses the LBT AO system, and we have demonstrated its ability to obtain spatially resolved spectra of close (theta < 1'') binary stars.

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