Improving the ability of image sensors to detect faint stars and moving objects using image deconvolution techniques

In this paper we show how the techniques of image deconvolution can increase the ability of image sensors as, for example, CCD imagers, to detect faint stars or faint orbital objects (small satellites and space debris). In the case of faint stars, we show that this benefit is equivalent to double the quantum efficiency of the used image sensor or to increase the effective telescope aperture by more than 30% without decreasing the astrometric precision or introducing artificial bias. In the case of orbital objects, the deconvolution technique can double the signal-to-noise ratio of the image, which helps to discover and control dangerous objects as space debris or lost satellites. The benefits obtained using CCD detectors can be extrapolated to any kind of image sensorsPeer ReviewedPostprint (published version

Modern optical astronomy: technology and impact of interferometry

The present `state of the art' and the path to future progress in high spatial resolution imaging interferometry is reviewed. The review begins with a treatment of the fundamentals of stellar optical interferometry, the origin, properties, optical effects of turbulence in the Earth's atmosphere, the passive methods that are applied on a single telescope to overcome atmospheric image degradation such as speckle interferometry, and various other techniques. These topics include differential speckle interferometry, speckle spectroscopy and polarimetry, phase diversity, wavefront shearing interferometry, phase-closure methods, dark speckle imaging, as well as the limitations imposed by the detectors on the performance of speckle imaging. A brief account is given of the technological innovation of adaptive-optics (AO) to compensate such atmospheric effects on the image in real time. A major advancement involves the transition from single-aperture to the dilute-aperture interferometry using multiple telescopes. Therefore, the review deals with recent developments involving ground-based, and space-based optical arrays. Emphasis is placed on the problems specific to delay-lines, beam recombination, polarization, dispersion, fringe-tracking, bootstrapping, coherencing and cophasing, and recovery of the visibility functions. The role of AO in enhancing visibilities is also discussed. The applications of interferometry, such as imaging, astrometry, and nulling are described. The mathematical intricacies of the various `post-detection' image-processing techniques are examined critically. The review concludes with a discussion of the astrophysical importance and the perspectives of interferometry.Comment: 65 pages LaTeX file including 23 figures. Reviews of Modern Physics, 2002, to appear in April issu

Planetary astronomy

The authors profile the field of astronomy, identify some of the key scientific questions that can be addressed during the decade of the 1990's, and recommend several facilities that are critically important for answering these questions. Scientific opportunities for the 1990' are discussed. Areas discussed include protoplanetary disks, an inventory of the solar system, primitive material in the solar system, the dynamics of planetary atmospheres, planetary rings and ring dynamics, the composition and structure of the atmospheres of giant planets, the volcanoes of IO, and the mineralogy of the Martian surface. Critical technology developments, proposed projects and facilities, and recommendations for research and facilities are discussed

Topics in Adaptive Optics

Advances in adaptive optics technology and applications move forward at a rapid pace. The basic idea of wavefront compensation in real-time has been around since the mid 1970s. The first widely used application of adaptive optics was for compensating atmospheric turbulence effects in astronomical imaging and laser beam propagation. While some topics have been researched and reported for years, even decades, new applications and advances in the supporting technologies occur almost daily. This book brings together 11 original chapters related to adaptive optics, written by an international group of invited authors. Topics include atmospheric turbulence characterization, astronomy with large telescopes, image post-processing, high power laser distortion compensation, adaptive optics and the human eye, wavefront sensors, and deformable mirrors

An Investigation Of Six Poorly Described Close Visual Double Stars Using Speckle Interferometry

Continued observation of double stars is necessary for confirmation of binarity and to provide updates to astrometric data used to compute accurate binary orbital parameters, thereby more accurately informing stellar mass estimations – the critical parameter from which stellar models are derived. In October of 2013, six double stars from the Washington Double Star (WDS) catalog exhibiting close separations, as well as significant deviations from previously published orbits, were observed and imaged using the speckle interferometric technique on the 2.1-meter telescope at Kitt Peak National Observatory (KPNO) in Arizona. The observations of the six double stars occurred as part of large, collaborative, eight-night, student-learning-centered observing run organized by principal investigator Genet of California Polytechnic Institute. The run produced in total roughly 1000 raw speckle images for each of the more than 1000 double stars and single reference stars observed, resulting in a total database of 1.4 terabytes. The speckle images for the targets, including the six targets investigated in this thesis, were taken using a relatively low-cost, portable speckle interferometry camera system developed by Genet, the heart of which is a lightweight, high speed, high signal to noise ratio (SNR) Andor electron multiplying CCD (EMCCD) camera capable of exposures on the order of tens of milliseconds. Exposures of 10-20 milliseconds are faster than atmospheric coherence timescales, and allow for the implementation of the speckle interferometry – the obtainment of diffraction-limited image information of binary stars defined by the full aperture of the telescope from the autocorrelation and Fourier analysis of randomly distributed, isoplanatically correlated speckle pairs, which represent the diffraction-limited images of the associated coherence cells above and within the atmospheric area of the primary aperture (sub-apertures). Following the Oct. 2013 observing run, reduction and analysis of the speckle images for the six target binary stars (as well as five calibration binaries) and determination of the new astrometry was completed using the general purpose astrometry software program PlateSolve3 (PS3), written and developed by Rowe & Genet (2014). Using the new astrometric data derived from the Oct. 2013 2.1-meter speckle observations, the previously published United States Naval Observatory (USNO) orbital plots for the six target doubles were updated to reflect the new, and in some cases missing measurements. Target double star orbits were reevaluated in light of the updates in order to draw conclusions about the characteristics of each proposed binary system. In all six target cases, continued trends in significant astrometric deviations from published orbits and ephemerides have been demonstrated by the new observations, indicating the need for orbital revisions of these binaries. Analysis of systems WDS22357+5413, WDS02231+7021, and WDS06256+2227 indicate rectilinear rather than Keplerian motion, and are concluded to likely be optical doubles. As a result of this work, two observations of WDS05153+4710 were shown to be erroneous and have been scheduled to be removed from this binary’s WDS observational record (Mason, private communication, 2015). Complementary to the central goal of investigating the six target close visual double stars via speckle interferometry, the entire effort demonstrated the applicability and utilization of relatively low-cost portable speckle camera systems on large telescopes, as well as the value and advantages of student participation and contribution within the realm of a large-scale observing run at a major observatory and the resulting peer reviewed scientific works that follow

Optical Tracking and Spectral Characterization of Cubesats for Operational Missions

Orbital debris in low Earth orbit is of growing concern to operational satellites from the government and commercial sector. With an uptick in worldwide satellite launches and the growing adoption of the CubeSat standard, the number of small objects in orbit are increasing at a faster pace than ever. As a result, a cascading collision event seems inevitable in the near future. The United States Strategic Command tracks and determines the orbit of resident space objects using a worldwide network of radar and optical sensors. However, in order to better protect space assets, there has been increased interest in not just knowing where a space object is, but what the object is. The optical and spectral characteristics of solar light reflected off of satellites or debris can provide information on the physical state or identity of the object. These same optical signatures can be used for mission support of operational satellite missions- down to satellites as small as CubeSats. Optical observation of CubeSats could provide independent monitoring of spin rate, deployable status, identification of individual CubeSats in a swarm, or possibly attitude information. This thesis first introduces the reader to a review of available observation techniques followed by the basics of observational astronomy relevant to satellite tracking. The thesis then presents the OSCOM system- a system for Optical tracking and Spectral characterization of CubeSats for Operational Missions. OSCOM is a ground-based system capable of observing and characterizing small debris and CubeSats with commercially available optical telescopes and detectors. The system is just as applicable for larger satellites which have higher signal to noise ratio. The OSCOM system has been used to successfully collect time-series photometry of more than 60 unique satellites of all sizes. Selected photometry results are presented along with a discussion of the technical details required for optical observation of small satellites

Working Papers: Astronomy and Astrophysics Panel Reports

The papers of the panels appointed by the Astronomy and Astrophysics survey Committee are compiled. These papers were advisory to the survey committee and represent the opinions of the members of each panel in the context of their individual charges. The following subject areas are covered: radio astronomy, infrared astronomy, optical/IR from ground, UV-optical from space, interferometry, high energy from space, particle astrophysics, theory and laboratory astrophysics, solar astronomy, planetary astronomy, computing and data processing, policy opportunities, benefits to the nation from astronomy and astrophysics, status of the profession, and science opportunities

GEMS: Galaxy Evolution from Morphologies and SEDs

GEMS, Galaxy Evolution from Morphologies and SEDs, is a large-area (800 arcmin2) two-color (F606W and F850LP) imaging survey with the Advanced Camera for Surveys on HST. Centered on the Chandra Deep Field South, it covers an area of ~28'x28', or about 120 Hubble Deep Field areas, to a depth of m_AB(F606W)=28.3 (5sigma and m_AB(F850LP)=27.1 (5sigma) for compact sources. In its central ~1/4, GEMS incorporates ACS imaging from the GOODS project. Focusing on the redshift range 0.2<=z<=1.1, GEMS provides morphologies and structural parameters for nearly 10,000 galaxies where redshift estimates, luminosities and SEDs exist from COMBO-17. At the same time, GEMS contains detectable host galaxy images for several hundred faint AGN. This paper provides an overview of the science goals, the experiment design, the data reduction and the science analysis plan for GEMS.Comment: 24 pages, TeX with 6 eps Figures; to appear in ApJ Supplement. Low resolution figures only. Full resolution at http://zwicky.as.arizona.edu/~rix/Misc/GEMS.ps.g