A5089434876- Photocathodes and Microchannel Plates
- Astro and Planetary Science
- Solar and Space Plasma Dynamics
- Astronomy and Astrophysical Research
- Atmospheric Ozone and Climate
- Calibration and Measurement Techniques
- Stellar, planetary, and galactic studies
- Dark Matter and Cosmic Phenomena
- Planetary Science and Exploration
- Adaptive optics and wavefront sensing
- Astrophysics and Star Formation Studies
- Geological and Geochemical Analysis
- Astronomical Observations and Instrumentation
- Advanced X-ray Imaging Techniques
- Advanced Fiber Laser Technologies
- Hydrocarbon exploration and reservoir analysis
- earthquake and tectonic studies
- Particle Detector Development and Performance
- Spectroscopy and Laser Applications
- Galaxies: Formation, Evolution, Phenomena
- Electron and X-Ray Spectroscopy Techniques
- Astrophysical Phenomena and Observations
- Plasma Diagnostics and Applications
- Ionosphere and magnetosphere dynamics
- Infrared Target Detection Methodologies
Southwest Research Institute
2023-2024
Johns Hopkins University
2016-2019
Johns Hopkins University Applied Physics Laboratory
2014-2018
University of Colorado Boulder
2003-2015
Laboratory for Atmospheric and Space Physics
2000-2015
University of Colorado System
2013
National Institute of Standards and Technology
2010
Fuse (United States)
2000
United States Naval Research Laboratory
1996-1997
American Society For Engineering Education
1994
The Far Ultraviolet Spectroscopic Explorer satellite observes light in the far-ultraviolet spectral region, 905-1187 Å, with a high resolution. instrument consists of four co-aligned prime-focus telescopes and Rowland spectrographs microchannel plate detectors. Two telescope channels use Al : LiF coatings for optimum reflectivity between approximately 1000 1187 other two SiC optimized throughput 905 1105 Å. gratings are holographically ruled to correct largely astigmatism minimize scattered...
Using the new Cosmic Origins Spectrograph (COS) on {\it Hubble Space Telescope (HST)}, we obtained moderate-resolution, high signal/noise ultraviolet spectra of HD 209458 and its exoplanet 209458b during transit, both orbital quadratures, secondary eclipse. We compare transit with at non-transit phases to identify spectral features due exoplanet's expanding atmosphere. find that mean flux decreased by $7.8\pm 1.3$% for C II 1334.5323\AA\ 1335.6854\AA\ lines $8.2\pm 1.4$% Si III 1206.500\AA\...
ABSTRACT We use high-quality, medium-resolution Hubble Space Telescope /Cosmic Origins Spectrograph ( HST /COS) observations of 82 UV-bright active galactic nuclei (AGNs) at redshifts z AGN < 0.85 to construct the largest survey low-redshift intergalactic medium (IGM) date: 5138 individual extragalactic absorption lines in H i and 25 different metal-ion species grouped into 2611 distinct redshift systems abs 0.75 covering total pathlengths Δ = 21.7 O vi 14.5. Our semi-automated...
A 12.5 GHz-spaced optical frequency comb locked to a Global Positioning disciplined oscillator for near-IR spectrograph calibration is presented. The generated via filtering 250 MHz-spaced comb. Subsequency nonlinear broadening of the GHz extends wavelength range cover 1380 nm 1820 nm, providing complete coverage over H-band transmission widow Earth's atmosphere. Finite suppression spurious sidemodes, linewidth and instability have been examined estmiate potential biases in calibration....
We present the scientific motivation and conceptual design for recently funded Habitable-zone Planet Finder (HPF), a stabilized fiber-fed near-infrared (NIR) spectrograph 10 meter class Hobby-Eberly Telescope (HET) that will be capable of discovering low mass planets around M dwarfs. The HPF cover NIR Y & J bands to enable precise radial velocities obtained on mid dwarfs, detection these stars. is comprised cryostat cooled 200K, dual fiber-feed with science calibration fiber, gold coated...
We present recent observations from the Hubble Space Telescope-Cosmic Origins Spectrograph aimed at characterizing auroral emission extrasolar planet HD 209458b. obtained medium-resolution (R ∼ 20,000) far-ultraviolet (1150–1700 Å) spectra both Phase 0.25 and 0.75 quadrature positions as well a stellar baseline measurement secondary eclipse. This analysis includes catalog of lines star-subtracted spectrum planet. an model for planetary H2 emission, compare this to spectrum. No unambiguously...
We present a high-resolution (R ~ 50 000) atlas of uranium-neon (U/Ne) hollow-cathode spectrum in the H-band (1454 nm to 1638 nm) for calibration near-infrared spectrographs. obtained this U/Ne simultaneously with laser-frequency comb spectrum, which we used provide first-order spectrum. then calibrated using recently-published uranium line list Redman et al. (2011), is derived from Fourier transform spectrometer measurements. These two independent calibrations allowed us easily identify...
Abstract We present a first-principles analytic treatment of modern multivane occulters in circular (coronagraph) and linear (heliospheric imager) geometry, develop simplified theory that is useful for designing predicting their performance, explain certain visual artifacts, explore the performance limits occulters. Multivane are challenging to design part because they violate conditions both Fraunhofer Fresnel approximations diffraction theory, new designs have therefore generally required...
We demonstrate that the G140L segment B channel of Cosmic Origins Spectrograph (COS) recently installed on {\it Hubble Space Telescope (HST)} has an effective area consistent with $\sim$ 10 cm$^2$ in bandpass between Lyman edge at 912 \AA and $\beta$, rising to a peak excess 1000 longward 1130 \AA. This is new wavelength regime for HST} will allow opportunities unique science investigations. In particular, investigations seeking quantify escape fraction continuum photons from galaxies low...
The Cosmic Origins Spectrograph (COS) on the Hubble Space Telescope (HST) uses a large-format cross delay line (XDL) detector in its Far Ultraviolet (FUV) channel. While obtaining spectra, light falls non-uniformly due to optical design and spectral properties of object being observed; particular, bright emission lines from geocoronal Lyman-alpha can fall more than 20 locations. As result, some areas have received much greater exposure others. This non-uniform illumination has led time-...
The Far Ultraviolet Spectroscopic Explorer (FUSE) satellite was launched into orbit on June 24, 1999. FUSE is now making high resolution ((lambda) /(Delta) (lambda) equals 20,000 - 25,000) observations of solar system, galactic, and extragalactic targets in the far ultraviolet wavelength region (905 1187 angstroms). Its effective area, low background, planned three year life allow objects which have been too faint for previous instruments this range. In paper, we describe on- performance...
<title>Abstract</title> We present results of a dual eclipse expedition to observe the solar corona from two sites during annular 2023 October 14, using novel coronagraph designed be accessible for amateurs and students build deploy. The CATEcor builds on standardized observing equipment developed Citizen CATE 2024 experiment. were selected likelihood clear observations, historic relevance (near Climax site in Colorado Rocky Mountains), centrality path (atop Sandia Peak above Albuquerque,...
The impact of gamma radiation on refractive index and transmission was analyzed for several glasses. goal the analysis is to quantify optical performance Jovian electron proton environments using as a proxy Europa Imaging System (EIS) Wide Angle Camera<sup>1</sup> (WAC) telescope. testing split into two sample sets. first set glasses tested are baselined in current WAC design: BK7G18, Calcium Fluoride, Fused Silica, LF5G15. Analysis demonstrates no significant change or LF5G15 when exposed 1...
Here we describe the observation and calibration procedure for a new G140L observing mode Cosmic Origins Spectrograph (COS) aboard Hubble Space Telescope (HST). This mode, CENWAV = 800, is designed to move far-UV band fully onto Segment A detector, allowing more e cient ob- servation analysis by simplifying management between two channels, reducing astigmatism in this wavelength region. We also de- scribe some of areas scientific interest which will be especially suited.
High groove density reflection gratings placed at grazing incidence in the extreme off-plane mount offer improved performance over conventional in-plane mounts x-ray. We present test results from grating evaluation facility University of Colorado for optimized use configuration. The tested are produce via holographic lithography. Gratings have radial patterns and include both blazed sinusoidal profiles. efficiency sub-aperture resolution results.
The Center for Astrophysics and Space Astronomy (CASA) recently delivered to the Johns Hopkins University Far Ultraviolet Spectrograph Instrument integration into far ultraviolet spectroscopic explorer (FUSE) satellite. In addition optical design of FUSE instrument, CASA/FUSE team was responsible development major components spectrograph final assembly alignment instrument.In this paper we present design, methodologies employed, performance characteristics instrument as University. addition,...
The Cosmic Origins Spacecraft (COS) will be the most sensitive UV spectrograph to flown aboard Hubble Space Telescope. COS FUV and NUV channels provide high sensitivity at resolution greater than 20000 over wavelengths ranging from 115 nm 320 nm. We present a brief review of instrument design grating test plan as well optical results for first delivered.
The Cosmic Origins Spectrograph (COS) will be the most sensitive UV spectrograph to flown aboard Hubble Space Telescope. COS FUV and NUV channels provide high sensitivity at resolution greater than 20000 over wavelengths ranging from 115nm 320nm. We present a brief review of instrument design, results optical testing gratings predicted on orbit performance.
The Cosmic Origins Spectrograph (COS) was installed on the Hubble Space Telescope (HST) in May 2009 during Servicing Mission 4 (SM4). This paper discusses initial on-orbit performance of HST-COS far ultraviolet (FUV) detector designed and built by Experimental Astrophysics Group at Univ. California, Berkeley. FUV is an open face, photon counting, microchannel plate (MCP) based device employing a cross delay line (XDL) readout. consists two separate, end-to-end segments (2x 85mm x 10mm -...
NASA's Europa Clipper will carry two cameras as part of the Imaging System (EIS). Both wide angle camera and narrow have identical focal plane modules, each containing a CMOS image sensor patterned optical filter array. The array enables multispectral pushbroom imaging in six bands, spanning 380nm to 1000 nm, adding additional science capability for surface characterization searching evidence recent activity. EIS is monolithic construction, with all bands coated on single substrate. Each...