Showing papers by "Katie M. Morzinski published in 2010"
Massachusetts Institute of Technology1, American Association of Variable Star Observers2, Williams College3, Las Cumbres Observatory Global Telescope Network4, Lowell Observatory5, Carnegie Institution for Science6, Leeward Community College7, University of Southern Queensland8, University of Nebraska–Lincoln9, National Autonomous University of Mexico10, IBM11, University of Texas at Brownsville12, Universities Space Research Association13, New Mexico Institute of Mining and Technology14, University of California, Santa Cruz15, James Cook University16, Harvard University17, National Autonomous University of Nicaragua18
TL;DR: Observations of a multi-chord stellar occultation by KBO 55636, which occurred on 9 October 2009, find that it has a mean radius of 143 ± 5 km and a geometric albedo of in the V photometric band, which establishes that KBO55636 is smaller than previously thought and that, like its parent body, it is highly reflective.
Abstract: The Kuiper belt is a collection of small bodies (Kuiper belt objects, KBOs) that lie beyond the orbit of Neptune and which are believed to have formed contemporaneously with the planets. Their small size and great distance make them difficult to study. KBO 55636 (2002 TX300) is a member of the water-ice-rich Haumea KBO collisional family. The Haumea family are among the most highly reflective objects in the Solar System. Dynamical calculations indicate that the collision that created KBO 55636 occurred at least 1 Gyr ago. Here we report observations of a multi-chord stellar occultation by KBO 55636, which occurred on 9 October 2009 ut. We find that it has a mean radius of 143 ± 5 km (assuming a circular solution). Allowing for possible elliptical shapes, we find a geometric albedo of 0.88 +0.15 -0.06 in the V photometric band, which establishes that KBO 55636 is smaller than previously thought and that, like its parent body, it is highly reflective. The dynamical age implies either that KBO 55636 has an active resurfacing mechanism, or that fresh water-ice in the outer Solar System can persist for gigayear timescales.
93 citations
TL;DR: In this paper, the authors evaluate the performance of the VISIBLE-LIGHT Laser Guidestar Experiments instrument (ViLLaGEs) on the 1-meter Nickel telescope at Mt. Hamilton.
Abstract: At the University of California's Lick Observatory, we have implemented an on-sky testbed for next-generation
adaptive optics (AO) technologies. The Visible-Light Laser Guidestar Experiments instrument (ViLLaGEs)
includes visible-light AO, a micro-electro-mechanical-systems (MEMS) deformable mirror, and open-loop control
of said MEMS on the 1-meter Nickel telescope at Mt. Hamilton. (Open-loop in this sense refers to the MEMS
being separated optically from the wavefront sensing path; the MEMS is still included in the control loop.) Future
upgrades include predictive control with wind estimation and pyramid wavefront sensing. Our unique optical
layout allows the wavefronts along the open- and closed-loop paths to be measured simultaneously, facilitating
comparison between the two control methods. In this paper we evaluate the performance of ViLLaGEs in openand
closed-loop control, finding that both control methods give equivalent Strehl ratios of up to ~ 7% in I-band
and similar rejection of temporal power. Therefore, we find that open-loop control of MEMS on-sky is as effective
as closed-loop control. Furthermore, after operating the system for three years, we find MEMS technology to
function well in the observatory environment. We construct an error budget for the system, accounting for 130
nm of wavefront error out of 190 nm error in the science-camera PSFs. We find that the dominant known term
is internal static error, and that the known contributions to the error budget from open-loop control (MEMS
model, position repeatability, hysteresis, and WFS linearity) are negligible.
21 citations
TL;DR: Evaluated ViLLaGEs in openand closed-loop control, finding that both control methods give equivalent Strehl ratios of up to ~ 7% in I-band and similar rejection of temporal power and that the dominant known term is internal static error.
Abstract: At the University of California's Lick Observatory, we have implemented an on-sky testbed for next-generation adaptive optics (AO) technologies. The Visible-Light Laser Guidestar Experiments instrument (ViLLaGEs) includes visible-light AO, a micro-electro-mechanical-systems (MEMS) deformable mirror, and open-loop control of said MEMS on the 1-meter Nickel telescope at Mt. Hamilton. In this paper we evaluate the performance of ViLLaGEs in open- and closed-loop control, finding that both control methods give equivalent Strehl ratios of up to ~ 7% in I-band and similar rejection of temporal power. Therefore, we find that open-loop control of MEMS on-sky is as effective as closed-loop control. Furthermore, after operating the system for three years, we find MEMS technology to function well in the observatory environment. We construct an error budget for the system, accounting for 130 nm of wavefront error out of 190 nm error in the science-camera PSFs. We find that the dominant known term is internal static error, and that the known contributions to the error budget from open-loop control (MEMS model, position repeatability, hysteresis, and WFS linearity) are negligible.
16 citations