KAPAO: a MEMS-based natural guide star adaptive optics system

We describe KAPAO, our project to develop and deploy a low-cost, remote-access, natural guide star adaptive optics (AO) system for the Pomona College Table Mountain Observatory (TMO) 1-meter telescope. We use a commercially available 140-actuator BMC MEMS deformable mirror and a version of the Robo-AO control software developed by Caltech and IUCAA. We have structured our development around the rapid building and testing of a prototype system, KAPAO-Alpha, while simultaneously designing our more capable final system, KAPAO-Prime. The main differences between these systems are the prototype's reliance on off-the-shelf optics and a single visible-light science camera versus the final design's improved throughput and capabilities due to the use of custom optics and dual-band, visible and near-infrared imaging. In this paper, we present the instrument design and on-sky closed-loop testing of KAPAO-Alpha as well as our plans for KAPAO-Prime. The primarily undergraduate-education nature of our partner institutions, both public (Sonoma State University) and private (Pomona and Harvey Mudd Colleges), has enabled us to engage physics, astronomy, and engineering undergraduates in all phases of this project. This material is based upon work supported by the National Science Foundation under Grant No. 0960343.Comment: 10 pages and 11 figure

Intercomparison of Field Methods for Acquiring Ground Reflectance at Railroad Valley Playa for Spectral Calibration of Satellite Data

Ground reflectance was acquired at the Railroad Valley Playa calibration site in Nevada USA using different methods of collection. The data was collected near the time and date of Landsat 8 OLI and Sentinel-2 satellite overpasses so an inter-comparison could be made with the reflectance products to determine which method was more suitable for vicarious calibration. The field spectrometers and reference panels were characterized before the field campaign. A continuous acquisition method was compared to stop and measure collections. Both acquisition methods were collected along an 80 m east-west transect as well as for a series of north-south transects over an 80 x 320 m area, with the stop and measure method being performed at random sampling locations. The measurements were performed using two field spectrometers by three teams of two people to compare the repeatability. The aim of the field campaign was to determine the variability due to the operator and the method of collection

KAPAO First Light: the design, construction and operation of a low-cost natural guide star adaptive optics system

We present the instrument design and first light observations of KAPAO, a natural guide star adaptive optics (AO) system for the Pomona College Table Mountain Observatory (TMO) 1-meter telescope. The KAPAO system has dual science channels with visible and near-infrared cameras, a Shack-Hartmann wavefront sensor, and a commercially available 140-actuator MEMS deformable mirror. The pupil relays are two pairs of custom off-axis parabolas and the control system is based on a version of the Robo-AO control software. The AO system and telescope are remotely operable, and KAPAO is designed to share the Cassegrain focus with the existing TMO polarimeter. We discuss the extensive integration of undergraduate students in the program including the multiple senior theses/capstones and summer assistantships amongst our partner institutions. This material is based upon work supported by the National Science Foundation under Grant No. 0960343

Simultaneous Spectroscopic Determination of Ion Temperature, Electron Density, and Magnetic Field for the ZaP-HD Experiment

Thesis (Master's)--University of Washington, 2015For over a decade, the ZaP Flow Z-Pinch experiment has demonstrated a sheared-flow stabi- lized Z-pinch, a linear plasma configuration with longitudinal current flow and azimuthal magnetic field confinement. A recent upgrade to the ZaP experiment, named ZaP-HD, looks to investigate the scaling relation that could plot its course towards a viable fusion reactor. This thesis documents the simultaneous measurement of the key magnetohydrodynamic parameters of ion temperature, electron density, and magnetic field on the ZaP-HD experiment. Temperature, electron density, and magnetic field each contribute a unique line-altering mechanism to the line radiation emitted from the ZaP-HD plasma. Through a least-squares fit in both the natural and Fourier domain to the emission spectrum of a C IV line at 581.2 nm known a priori to have the form of a Voigt profile, each of the desired parameters can be resolved for sufficiently small noise levels. Noise levels, de- fined as the ratio of the standard deviation of the noise in a dark region of the spectrum to the peak signal amplitude, at or below around 1% provide measurements corroborated by other diagnostics on the ZaP-HD experiment