A preliminary experiment definition for video landmark acquisition and tracking

Six scientific objectives/experiments were derived which consisted of agriculture/forestry/range resources, land use, geology/mineral resources, water resources, marine resources and environmental surveys. Computer calculations were then made of the spectral radiance signature of each of 25 candidate targets as seen by a satellite sensor system. An imaging system capable of recognizing, acquiring and tracking specific generic type surface features was defined. A preliminary experiment definition and design of a video Landmark Acquisition and Tracking system is given. This device will search a 10-mile swath while orbiting the earth, looking for land/water interfaces such as coastlines and rivers

High Resolution Ozone Mapper (HROM)

Using the backscatter ultraviolet instrument (BUV) aboard NIMBUS 4 as a baseline, point scanner mechanisms and spatial multiplex scanning systems were compared on the basis of sensitivity, field of view and simplicity. This comparison included both spectral and spatial scanning and multiplexing techniques. The selected system which optimally met the performance requirements for a shuttle based instrument was a pushbroom spatial scanner using a 15 element photomultiplier tube array and a Hadamard multiplex spectral scan. The selected system was conceptually designed. This design includes ray traces of the monochromator, mechanical layouts and the electronic block diagram

Hectospec, the MMT's 300 Optical Fiber-Fed Spectrograph

The Hectospec is a 300 optical fiber fed spectrograph commissioned at the MMT in the spring of 2004. A pair of high-speed six-axis robots move the 300 fiber buttons between observing configurations within ~300 s and to an accuracy ~25 microns. The optical fibers run for 26 m between the MMT's focal surface and the bench spectrograph operating at R~1000-2000. Another high dispersion bench spectrograph offering R~5,000, Hectochelle, is also available. The system throughput, including all losses in the telescope optics, fibers, and spectrograph peaks at ~10% at the grating blaze in 1" FWHM seeing. Correcting for aperture losses at the 1.5" diameter fiber entrance aperture, the system throughput peaks at $\sim$17%. Hectospec has proven to be a workhorse instrument at the MMT. Hectospec and Hectochelle together were scheduled for 1/3 of the available nights since its commissioning. Hectospec has returned \~60,000 reduced spectra for 16 scientific programs during its first year of operation.Comment: 68 pages, 28 figures, to appear in December 2005 PAS

Modern Observational Techniques for Comets

Techniques are discussed in the following areas: astrometry, photometry, infrared observations, radio observations, spectroscopy, imaging of coma and tail, image processing of observation. The determination of the chemical composition and physical structure of comets is highlighted

Astrometry with the Keck-Interferometer: the ASTRA project and its science

The sensitivity and astrometry upgrade ASTRA of the Keck Interferometer is introduced. After a brief overview of the underlying interferometric principles, the technology and concepts of the upgrade are presented. The interferometric dual-field technology of ASTRA will provide the KI with the means to observe two objects simultaneously, and measure the distance between them with a precision eventually better than 100 uas. This astrometric functionality of ASTRA will add a unique observing tool to fields of astrophysical research as diverse as exo-planetary kinematics, binary astrometry, and the investigation of stars accelerated by the massive black hole in the center of the Milky Way as discussed in this contribution.Comment: 22 pages, 10 figures (low resolution), contribution to the summerschool "Astrometry and Imaging with the Very Large Telescope Interferometer", 2 - 13 June, 2008, Keszthely, Hungary, corrected authorlis

The Unusual Infrared Object HDF-N J123656.3+621322

We describe an object in the Hubble Deep Field North with very unusual near-infrared properties. It is readily visible in Hubble Space Telescope NICMOS images at 1.6um and from the ground at 2.2um, but is undetected (with signal-to-noise <~ 2) in very deep WFPC2 and NICMOS data from 0.3 to 1.1um. The f_nu flux density drops by a factor >~ 8.3 (97.7% confidence) from 1.6 to 1.1um. The object is compact but may be slightly resolved in the NICMOS 1.6um image. In a low-resolution, near-infrared spectrogram, we find a possible emission line at 1.643um, but a reobservation at higher spectral resolution failed to confirm the line, leaving its reality in doubt. We consider various hypotheses for the nature of this object. Its colors are unlike those of known galactic stars, except perhaps the most extreme carbon stars or Mira variables with thick circumstellar dust shells. It does not appear to be possible to explain its spectral energy distribution as that of a normal galaxy at any redshift without additional opacity from either dust or intergalactic neutral hydrogen. The colors can be matched by those of a dusty galaxy at z >~ 2, by a maximally old elliptical galaxy at z >~ 3 (perhaps with some additional reddening), or by an object at z >~ 10 whose optical and 1.1um light have been suppressed by the intergalactic medium. Under the latter hypothesis, if the luminosity results from stars and not an AGN, the object would resemble a classical, unobscured protogalaxy, with a star formation rate >~ 100 M_sun/yr. Such UV-bright objects are evidently rare at 2 < z < 12.5, however, with a space density several hundred times lower than that of present-day L* galaxies.Comment: Accepted for publication in the Astrophysical Journal. 27 pages, LaTeX, with 7 figures (8 files); citations & references updated + minor format change

Spectroscopic studies on AGNs and High angular resolution in the NIR: The construction of an imaging beam combiner for the LBT

The current thesis is divided into two projects. The first part deals with studies on active galaxies hosting an Active Galactic Nucleus (AGN). Specifically, an optical spectroscopic study of a nearby (z < 0.06) volume - limited sample of Low - Luminosity Quasi - Stellar Objects (LLQSOs) has been carried out. The sample has been drawn from the Hamburg/ESO QSO survey (HES), which has a well-defined flux limit of B_j < 17.3. The aim of the present project is to characterize the excitation degree of the sample, distinguish between possible star forming and Seyfert activity and to investigate the spectral characteristics of the sample. The spectroscopic data were analyzed and emission lines were fitted using a routine, which employs Levenberg - Marquardt least square minimization. The same analysis was also applied for some additional archival data from the 6 Degree Field Galaxy Survey (6dFGS). The objects of the LLQSOs sample are classified according to the classical optical diagnostic diagrams, based on optical emission lines close in wavelength, avoiding almost any impact of reddening. The diagrams provide a diagnosis of the ionizing source within a galaxy, hence activity between Hii, LINERs (Low Ionization Nuclear Emission-line Region), and Seyfert galaxies can be clearly distinguished. The classification of all members of the LLQSOs sample is shown in chapter 3. The broadness of the emission lines, cases with double components and the electron density are also analyzed. The comparison of the diagnostic diagrams between the two data sets (HES and 6DFGS) results in different classifications of most of the sources. This is due to the different spectroscopic techniques applied in the two data sets during the observations, and is sketched in chapter 4. Several galaxies at a variety of cosmological distances, with elliptical and circular morphologies, were simulated. In these simulations, different instruments (different spectroscopic techniques, i.e. slit, fiber) were applied to the galaxies, in order to study the instrumental effect (aperture effect). The impact of the aperture effect in local and high redshift universe is discussed in detail. The second project of the thesis focuses on the construction of an image beam combiner for the Large Binocular Telescope (LBT). The LINC - NIRVANA instrument will be operating in the near - infrared (1 - 2.4 μm) and will provide a high angular resolution (~9 mas at 1.25 μm) over a wide field of view (~100 arcsec at 1.25 μm). A fundamental component of the instrument, the Fringe and Flexure Tracking System (FFTS) is responsible to ensure a complete and time-stable wavefront correction at the position of the science detector. This will allow for long integration times at interferometric angular resolutions. A historical overview and our current achievements are also discussed in chapter 5. Laboratory tests of specific parts of the FFTS are presented in chapter 6. Especially, the subparts of the Detector Positioning Unit (DPU), which has to be moved with respect to an altitude - azimuth mounting under vacuum conditions, are characterized. The tilting of the instrument as a function of elevation results in a flexure of the system that has to be corrected by an algorithm

Observations of breakup processes of liquid jets using real-time X-ray radiography

To unravel the liquid-jet breakup process in the nondilute region, a newly developed system of real-time X-ray radiography, an advanced digital image processor, and a high-speed video camera were used. Based upon recorded X-ray images, the inner structure of a liquid jet during breakup was observed. The jet divergence angle, jet breakup length, and fraction distributions along the axial and transverse directions of the liquid jets were determined in the near-injector region. Both wall- and free-jet tests were conducted to study the effect of wall friction on the jet breakup process

Science aspects of a 1980 flyby of Comet Encke with a Pioneer spacecraft

Results are presented of an investigation of the feasibility of a 1980 flyby of Comet Encke using a Pioneer class spacecraft. Specific areas studied include: science objectives and rationale; science observables; effects of encounter velocity; science encounter and targeting requirements; selection and description of science instruments; definition of a candidate science payload; engineering characteristics of suggested payload; value of a separable probe; science instruments for a separable probe; science payload integration problems; and science operations profile