he WIYN 3.5m Telescope at Kitt Peak National Observatory hosts a suite of optical and near infrared instruments, including an extreme precision, optical spectrograph, NEID, built for exoplanet radial velocity studies. In order to achieve sub ms−1 precision, NEID has strict requirements on survey efficiency, stellar image positioning, and guiding performance, which have exceeded the native capabilities of the telescope’s original pointing and tracking system. In order to improve the operational efficiency of the telescope we have developed a novel telescope pointing system, built on a recurrent neural network, that does not rely on the usual pointing models (TPoint or other quasi-physical bases). We discuss the development of this system, how the intrinsic properties of the pointing problem inform our network design, and show preliminary results from our best models. We also discuss plans for the generalization of this framework, so that it can be applied at other sites.
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).
To help the prospective observer take full advantage of the mid-IR capability of Gemini South, we characterize a key aspect of the mid-IR performance of the 8-meter telescope at Gemini-S, namely, the appearance and stability of its delivered mid-IR image profiles, with the goal of demonstrating that it can be used with a level
of precision not used before. About 2000 images obtained with T-ReCS (a facility mid-IR camera at Gemini-S) between late 2003 and early 2009 were used for our image quality analysis. All targets are flux standards and recorded at one or more of the four bands Si-2 (8.74 μm), N (10.36 μm), Si-5 (11.66 μm), and Qa (18.3 μm).
A non-linear least squares fitting of three profile models (Lorentzian, Gaussian, and Moffat) was performed on
each image, and key parameters such as FWHM, ellipticity, position angle and Strehl-ratio were measured from
the fitted profile. We find that the long-time-scale image quality is quite stable in terms of profile width or
ellipticity, though short-time-scale variation is evident. We also examined the correlation between image quality
and many ambient parameters and confirmed the interdependence between the image quality in the Qa band
and the ambient humidity. The ellipticity of the profile was analyzed statistically as well. The average profiles
for different filters can be used as important references in the future when a high-quality profile reference is not
available during an observation.
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