This presentation discusses the design and performance of the recent upgrade to the fiber positioning robot in Hydra, a multi-object spectrograph at the WIYN 3.5m telescope. After 31 years of operation, and more than two decades as the mainstay of optical spectroscopy at WIYN, the workhorse instrument was unreliable and difficult to maintain. The new “gripper” robot is twice as fast as the previous version, substantially reducing night time lost to reconfiguring fiber fields. Additionally, the two previously most common error modes, dropping fibers and failing to grab fibers, both of which required manual intervention, have been eliminated thanks to the introduction of machine vision and an improved sensing system. Hydra21 uses industrial standard electronics (programmable logic controllers, PLCs) which are extremely reliable and allow for straightforward future software upgrades, including the possibility of accommodating new fibers of different sizes. The PLC framework also provides detailed telemetry, and easy access to low level commands for diagnostic and maintenance work. This presentation also reports on the formation of a new partnership between the academic and government funded observatory and an industrial automation firm (PROD Design & Analysis, Inc, based out of El Paso, Texas). This partnership provided us the flexibility to combine in-house expertise with contracted engineering resources and will be a template for ongoing modernization of the WIYN observatory. Lessons learned from working with a vendor who was new to astronomical instrumentation are shared, though we emphasize our ultimate success.
NEID (NN-explore Exoplanet Investigations with Doppler spectroscopy) is an optical, fiber-fed spectrometer at the WIYN 3.5m Telescope. NEID’s single-measurement radial velocity precision (27 cm/s) requires the stellar image motion (induced by atmospheric turbulence) to be controlled for 90% of the time to within 50 milli-arcseconds in nominal observing conditions. This has been achieved by fast guiding through the NEID Port Adapter, which implements an EMCCD and a tip/tilt piezo stage to capture/stabilize the stellar image. Here, we use on-sky data accumulated over a year to demonstrate the performance of this system under diverse observing conditions.
Here we detail the on-sky performance of the NEID Port Adapter one year into full science operation at the WIYN 3.5m Telescope at Kitt Peak National Observatory. NEID is an optical (380-930 nm), fiber-fed, precision Doppler radial velocity system developed as part of the NASA-NSF Exoplanet Observational Research (NN-EXPLORE) partnership. The NEID Port Adapter mounts directly to a bent-Cassegrain port on the WIYN Telescope and is responsible for precisely and stably placing target light on the science fibers. Precision acquisition and guiding is a critical component of such extreme precision spectrographs. In this work, we describe key on-sky performance results compared to initial design requirements and error budgets. While the current Port Adapter performance is more than sufficient for the NEID system to achieve and indeed exceed its formal instrumental radial velocity precision requirements, we continue to characterize and further optimize its performance and efficiency. This enables us to obtain better NEID datasets and in some cases, improve the performance of key terms in the error budget needed for future extreme precision spectrographs with the goal of observing ExoEarths, requiring ∼ 10 cm/s radial velocity measurements.
The NEID extreme precision radial velocity spectrometer is in operation at the WIYN 3.5-meter telescope located at the Kitt Peak National Observatory, Tucson, Arizona. This newly-commissioned instrument serves both the national exoplanet research community as well as the WIYN consortium partners. In order to meet the stringent 27 cm per second radial velocity precision[1], and in particular to maximize the efficiency of the 5-year radial velocity survey, it is critical to understand the WIYN telescope vibration environment. In this presentation, we describe the vibration measurement techniques and results used for quantifying the vibration of: the telescope ancillary equipment, the telescope mount, the telescope primary mirror cooling systems, the telescope instruments, wind, and other sources and their effect on the telescope image. Additionally, mitigation methods, current and planned are discussed. This work continues on from a previous paper at this conference[2], where we presented data gathered from accelerometers on WIYN to begin identifying major features in the vibration spectra and simulate the input to the tip-tilt correction system for the NEID fiber-feed. The WIYN telescope has a well-ventilated and compact dome that ensures excellent seeing, but is also prone to wind-shake. For wind-related vibrations in particular, it is important to model the structural modes to design mitigation strategies and here we discuss possible experimental methods and data analysis techniques to address this. This work will be relevant to upgrade and retrofit efforts as older observatories incorporate low-order wavefront correction to stabilize light to advanced spectrometers and imagers. See Li et al. (this conference).
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