Carl T. Coker
A5067731197- Stellar, planetary, and galactic studies
- Adaptive optics and wavefront sensing
- Astronomy and Astrophysical Research
- Galaxies: Formation, Evolution, Phenomena
- Astrophysics and Star Formation Studies
- Astrophysical Phenomena and Observations
- Astronomical Observations and Instrumentation
- Astro and Planetary Science
- Optical Polarization and Ellipsometry
- Advanced optical system design
- Astrophysics and Cosmic Phenomena
- Gamma-ray bursts and supernovae
- Optical Wireless Communication Technologies
- Optical Systems and Laser Technology
- Spectroscopy and Laser Applications
- Industrial Vision Systems and Defect Detection
- Advanced Fiber Laser Technologies
- Semiconductor Lasers and Optical Devices
- Radio Astronomy Observations and Technology
- Photonic Crystal and Fiber Optics
- Calibration and Measurement Techniques
- Scientific Research and Discoveries
- Pulsars and Gravitational Waves Research
- Photonic and Optical Devices
- Statistical and numerical algorithms
Northrop Grumman (United States)
2021-2023
Jet Propulsion Laboratory
2017-2022
California Institute of Technology
2020-2022
The Ohio State University
2013-2019
DESI (Dark Energy Spectroscopic Instrument) is a Stage IV ground-based dark energy experiment that will study baryon acoustic oscillations (BAO) and the growth of structure through redshift-space distortions with wide-area galaxy quasar redshift survey. To trace underlying matter distribution, spectroscopic targets be selected in four classes from imaging data. We measure luminous red galaxies up to $z=1.0$. probe Universe out even higher redshift, target bright [O II] emission line $z=1.7$....
We present the first results from an optical reverberation mapping campaign executed in 2014, targeting active galactic nuclei (AGN) MCG+08-11-011, NGC 2617, 4051, 3C 382, and Mrk 374. Our targets have diverse interesting observational properties, including a "changing look" AGN broad-line radio galaxy. Based on continuum-H$\beta$ lags, we measure black hole masses for all five targets. also obtain H$\gamma$ He{\sc ii}\,$\lambda 4686$ lags objects except 382. The indicate radial...
We present the results of an optical spectroscopic monitoring program targeting NGC 5548 as part a larger multi-wavelength reverberation mapping campaign. The campaign spanned six months and achieved almost daily cadence with observations from five ground-based telescopes. H$\beta$ He II $\lambda$4686 broad emission-line light curves lag that 5100 $\AA$ continuum by $4.17^{+0.36}_{-0.36}$ days $0.79^{+0.35}_{-0.34}$ days, respectively. relative to 1158 ultraviolet curve measured Hubble Space...
Abstract We present optical continuum lags for two Seyfert 1 galaxies, MCG+08-11-011 and NGC 2617, using monitoring data from a reverberation mapping campaign carried out in 2014. Our light curves span the ugriz filters over four months, with median cadences of 1.0 0.6 days respectively, combined roughly daily X-ray near-UV Swift 2617. find consistent geometrically thin accretion-disk models that predict lag-wavelength relation τ ∝ λ 4/3 . However, observed are larger than predictions based...
The Fast Linearized Coronagraph Optimizer (FALCO) is an open-source toolbox of routines for coronagraphic focal plane wavefront correction. goal FALCO to provide a free, modular framework the simulation or testbed operation several common types coronagraphs. includes pair-wise probing estimation complex electric field and Electric Field Conjugation (EFC) control, we ask community contribute other correction algorithms. utilizes builds upon PROPER, established optical propagation library. key...
We report the discovery of KELT-12b, a highly inflated Jupiter-mass planet transiting mildly evolved host star. identified initial transit signal in KELT-North survey data and established planetary nature companion through precise follow-up photometry, high-resolution spectroscopy, radial velocity measurements, adaptive optics imaging. Our preferred best-fit model indicates that $V = 10.64$ host, TYC 2619-1057-1, has $T_{\rm eff} 6278 \pm 51$ K, $\log{g_\star} 3.89^{+0.054}_{-0.051}$, [Fe/H]...
We model the ultraviolet spectra of Seyfert 1 galaxy NGC~5548 obtained with Hubble Space Telescope during 6-month reverberation-mapping campaign in 2014. Our emission from NGC 5548 corrects for overlying absorption and deblends individual lines. Using modeled spectra, we measure response to continuum variations deblended absorption-corrected broad lines, velocity-dependent profiles Ly$\alpha$ C IV, narrow intrinsic features. find that time lags corrected lines are comparable those original...
Future space telescopes with coronagraph instruments will use a wavefront sensor (WFS) to measure and correct for phase errors stabilize the stellar intensity in high-contrast images. The HabEx LUVOIR mission concepts baseline Zernike (ZWFS), which uses Zernike's contrast method convert pupil into at WFS detector. In preparation these potential future missions, we experimentally demonstrate ZWFS instrument on Decadal Survey Testbed High Contrast Imaging facility NASA's Jet Propulsion...
During the Space Telescope and Optical Reverberation Mapping Project (STORM) observations of NGC 5548, continuum emission-line variability became de-correlated during second half 6-month long observing campaign. Here we present Swift Chandra X-ray spectra 5548 obtained as a part The show that excess flux (relative to power-law continuum) in soft band appears before start anomalous behavior, peaks period anomaly, then declines. This is model-independent result suggesting related anomaly. We...
We present the first results from a reverberation-mapping campaign undertaken during half of 2012, with additional data on one AGN (NGC 3227) 2014 campaign. Our main goals are (1) to determine black hole masses continuum-Hbeta reverberation signatures, and (2) look for velocity-dependent time delays that might be indicators gross kinematics broad-line region. successfully measure Hbeta five AGNs, four which have previous mass measurements. The values measured here in agreement earlier...
The planned Habitable Worlds Observatory (HWO) will be designed to find and characterize Earth-like planets in the habitable zones of sun-like stars. This mission require an instrument capable making measurements planet spectra at high contrast small inner working angles. Previous demonstrations existing coronagraph designs have not achieved these requirements 20% bandwidths or better required for full spectroscopic characterization, even a laboratory environment. One technique that shows...
We are conducting a search for binary companions around 11 hot-Jupiter hosts from the Kilodegree Extremely Little Telescope (KELT) survey and large comparison sample of stars shown by KELT to not host transiting hot Jupiter. The primary bright (7.5 < V 11) similar distance Earth (100 d 300 pc). In this paper, we present results our observations using Differential Speckle Survey Instrument. observed 9 14 planet that visible northern hemisphere 51 stars, discovering two new potential...
A concordance model for angular momentum evolution has been developed by multiple investigators. This approach postulates that star forming regions and clusters are an evolutionary sequence which can be modeled with assumptions about the coupling between protostars accretion disks, loss from magnetized winds saturates in a mass-dependent fashion at high rotation rates, core-envelope decoupling solar analogs. We test this combining established data large h Per dataset MONITOR project new...
High contrast imaging is the primary path to direct detection and characterization of Earth-like planets around solar-type stars; a cleverly designed internal coronagraph suppresses light from star, revealing elusive circumstellar companions. However, future large-aperture telescopes ($>$4~m in diameter) will likely have segmented mirrors, which causes additional diffraction unwanted stellar light. Here we present first high laboratory demonstration an apodized vortex (AVC), apodizer placed...
Coronagraph instruments on future space telescopes will enable the direct detection and characterization of Earth-like exoplanets around Sun-like stars for first time. The quest optimal optical coronagraph designs has made rapid progress in recent years thanks to Segmented Design Analysis (SCDA) initiative led by Exoplanet Exploration Program at NASA's Jet Propulsion Laboratory. As a result, several types high-performance have emerged that make use dual deformable mirrors (1) correct...
Radiation pressure on dust grains may be an important physical mechanism driving galaxy-wide superwinds in rapidly star-forming galaxies. We calculate the combined and gas Eddington ratio (Gamma) for archetypal superwind of M82. By combining archival GALEX data, a standard model, Monte Carlo scattering calculations, Herschel map surface density distribution, observed FUV/NUV brightness outflow constrains both total UV luminosity escaping from starburst along its minor axis (L_*, UV)...
Directly imaging and characterizing Earth-like exoplanets is a tremendously difficult instrumental challenge. Present coronagraphic systems have yet to achieve the required 10<sup> − 10</sup> broadband contrast in laboratory environment, but promising progress toward this goal continues. An approach starlight suppression use of single-mode fiber (SMF) behind coronagraph. By using deformable mirrors create mismatch between incoming mode, SMF can be turned into an integral part system. We...
We have developed the Fast Linearized Coronagraph Optimizer (FALCO), a new software toolbox for high-contrast, coronagraphic wavefront sensing and control. FALCO rapidly calculates linearized deformable mirror (DM) response matrices, also called control Jacobians, can be used design, simulation, or testbed operation of several types coronagraphs. In this paper, we demonstrate that optical propagation in is accurate matches PROPER. addition, drastic reduction runtime when using DM Jacobian...
Deformable mirrors (DMs) are increasingly becoming part of nominal coronagraph designs, such as the hybrid Lyot coronagraph, in addition to their role counteracting optical aberrations. Previous studies have investigated effects inter-DM Fresnel number on achievable contrast, throughput, and tip/tilt sensitivity for apodized coronagraphs augmented with DMs suppress diffraction from struts segment gaps. In this paper, we build upon that previous work by directly suppressing controller, both...
The Dark Energy Spectroscopic Instrument (DESI) is under construction to measure the expansion history of Universe using Baryon Acoustic Oscillation technique. spectra 40 million galaxies over 14,000 sq deg will be measured during life experiment. A new prime focus corrector for KPNO Mayall telescope deliver light 5000 fiber optic positioners. fibers in turn feed ten broad-band spectrographs. We describe unique shutter design that incorporates a illumination system into blade. When...
The High Contrast spectroscopy testbed for Segmented Telescopes (HCST) is being developed at Caltech. It aims addressing the technology gap future exoplanet imagers and providing U.S. community with an academic facility to test components techniques high contrast imaging, focusing on segmented apertures proposed ground-based (TMT, ELT) space-based telescopes (HabEx, LUVOIR). We present overview of design instrument a detailed look build initial alignment. offer insights into stumbling blocks...
The Dark Energy Spectroscopic Instrument (DESI) is under construction to measure the expansion history of Universe using Baryon Acoustic Oscillation technique. spectra 40 million galaxies over 14,000 sq deg will be measured during life experiment. A new prime focus corrector for KPNO Mayall telescope deliver light 5,000 fiber optic positioners. fibers in turn feed ten broad-band spectrographs. We present design details instrument mechanism control systems Each spectrograph has a stand-alone...
The High-Contrast Spectroscopy Testbed for Segmented Telescopes (HCST) in the Exoplanet Technology Laboratory (ET Lab) at Caltech is designed to test technologies that will enable direct imaging and characterization of exoplanets with future segmented ground- space-based telescopes. Wavefront sensing control has been successfully implemented electric field conjugation (EFC) using FALCO Matlab package, yielding a baseline raw contrast 1×10<sup>-8</sup> narrowband light Vector Vortex...
The fields of Astronomy and Astrophysics are technology limited, where the advent application new technologies to astronomy usher in a flood discoveries altering our understanding Universe (e.g., recent cases include LIGO GRAVITY instrument at VLTI). Currently, field astronomical spectroscopy is rapidly approaching an impasse: size cost instruments, especially multi-object integral spectrographs for extremely large telescopes (ELTs), pushing limits what feasible, requiring optical components...
To address the fundamental questions of exoplanetary science, future space-based observatories will have to obtain quality spectra a large enough set Earth-like planets around main-sequence stars. Although coronagraph instruments provide necessary observational efficiency probe many systems with respect starshade observation, they typically suffer from limited achievable bandwidth at contrast and relatively poor throughput off-axis sources. This is mainly due fact that starlight suppressed...