• Harvard-Smithsonian Ctr. for Astrophysics (United States)
• William Podgorski, Henry Bergner, Ian Evans, Janet Evans, Gabor Furesz, Kenneth McCracken, Mark Mueller, Timothy Norton, Sang Park, David Plummer, Andrew Szentgyorgyi
• The Univ. of Chicago (United States)
• Jacob Bean
• Korea Astronomy and Space Science Institute (Korea, Republic of)
• Moo-Young Chun, Kang-Min Kim, Chan Park, In-Soo Yuk
• Carnegie Observatories (United States)
• Jeffrey Crane, Alan Uomoto
• Pontificia Univ. Católica de Chile (Chile)
• Dani Guzman

abstract

One of the first light instruments for the Giant Magellan Telescope (GMT) will be the GMT-Consortium Large Earth Finder (G-CLEF). It is an optical band echelle spectrograph that is fiber fed to enable high stability. One of the key capabilities of G-CLEF will be its extremely precise radial velocity (PRV) measurement capability. The RV precision goal is 10 cm/sec, which is expected to be achieved with advanced calibration methods and the use of the GMT adaptive optics system. G-CLEF, as part of the GMT suite of instruments, is being designed within GMT's automated requirements management system. This includes requirements flow down, traceability, error budgeting, and systems compliance. Error budgeting is being employed extensively to help manage G-CLEF technical requirements and ensure that the top level requirements are met efficiently. In this paper we discuss the G-CLEF error budgeting process, concentrating on the PRV precision and instrument throughput budgets. The PRV error budgeting process is covered in detail, as we are taking a detailed systems error budgeting approach to the PRV requirement. This has proven particularly challenging, as the precise measurement of radial velocity is a complex process, with error sources that are difficult to model and a complex calibration process that is integral to the RV measurement. The PRV budget combines traditional modeling and analysis techniques, where applicable, with semi-empirical techniques, as necessary. Extrapolation from existing PRV instruments is also used in the budgeting process.

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