Highly linear, sensitive analog-to-digital converter

Analog-to-digital converter converts 10 volt full scale input signal into 13 bit digital output. Advantages include high sensitivity, linearity, low quantitizing error, high resistance to mechanical shock and vibration loads, and temporary data storage capabilities

Proper Motion of Pulsar B1800-21

We report high angular resolution, multi-epoch radio observations of the young pulsar PSR B1800-21. Using two pairs of data sets, each pair spanning approximately a ten year period, we calculate the proper motion of the pulsar. We obtain a proper motion of mu_alpha=11.6 +- 1.8 mas/yr, mu_delta=14.8 +- 2.3 mas/yr, which clearly indicates a birth position at the extreme edge of the W30 supernova remnant. Although this does not definitively rule out an association of W30 and PSR B1800-21, it does not support an association.Comment: 13 pages, 1 color figure. Replaced with version accepted for publication in Astrophysical Journa

X-Ray Spectral Variability of Extreme BL Lac AGN H1426+428

Between 7 March 2002 and 15 June 2002, intensive X-ray observations were carried out on the extreme BL Lac object H1426+428 with instruments on board the Rossi X-ray Timing Explorer (RXTE). These instruments provide measurements of H1426+428 in the crucial energy range that characterizes the first peak of its spectral energy distribution. This peak, which is almost certainly due to synchrotron emission, has previously been inferred to be in excess of 100 keV. By taking frequent observations over a four-month campaign, which included $\sim$450 ksec of RXTE time, studies of flux and spectral variability on multiple timescales were performed, along with studies of spectral hysteresis. The 3-24 keV X-ray flux and spectra exhibited significant variability, implying variability in the location of the first peak of the spectral energy distribution. Hysteresis patterns were observed, and their characteristics have been discussed within the context of emission models.Comment: accepted for publication in Astrophysical Journa

A Charge and Spin Readout Scheme For Single Self-Assembled Quantum Dots

We propose an all optical spin initialization and readout concept for single self assembled quantum dots and demonstrate its feasibility. Our approach is based on a gateable single dot photodiode structure that can be switched between charge and readout mode. After optical electron generation and storage, we propose to employ a spin-conditional absorption of a circularly polarized light pulse tuned to the single negatively charged exciton transition to convert the spin information of the resident electron to charge occupancy. Switching the device to the charge readout mode then allows us to probe the charge state of the quantum dot (1e, 2e) using non-resonant luminescence. The spin orientation of the resident electron is then reflected by the photoluminescence yield of doubly and singly charged transitions in the quantum dot. To verify the feasibility of this spin readout concept, we have applied time gated photoluminescence to confirm that selective optical charging and efficient non perturbative measurement of the charge state can be performed on the same dot. The results show that, by switching the electric field in the vicinity of the quantum dot, the charging rate can be switched between a regime of efficient electron generation and a readout regime, where the charge occupancy and, therefore, the spin state of the dot can be tested via PL over millisecond timescales, without altering it.Comment: 20 Pages, 6 Figures, submitted to Phys. Rev.

Test Plan for Remote Sensing Information Subsystem Products Test Site 1 (Coastal)

This plan outlines the map products to be generated from Landsat imagery, airborne multispectral scanner imagery, and aerial photography of a test site on the Texas coast. The objectives of producing these maps are: To determine the methodology necessary for developing each type of product. To designate the size, scale, level of detail, and final format of each map within an initial phase of development of remote sensing products. To designate specifications for the generation of equivalent products from aerial photography to be used in comparison evaluations. The map products and data analysis procedures described here are based on: Objectives outlined in the Applications System Verification and Transfer (ASVT) Project Plan (McCulloch and McKain, 1978). State agency coastal information needs and listings of possible products developed in conjunction with the User Advisory Group. The Remote Sensing Information Subsystem (RSIS) Level I Design and Design Review documents. As such, the descriptions contained herein are primarily conceptual and are derived from only limited hands-on experience with Landsat imagery and digital image processing hardware and software. Present time schedules call for the software required for full analysis of data over the Coastal Test Site to be available in early 1981.Bureau of Economic Geolog

Test Plan for Remote Sensing Information Subsystem Products Test Site 2 and 5 (High Plains and Trans-Pecos Texas)

This plan outlines the map products to be generated from Landsat imagery, airborne multispectral scanner imagery, and aerial photography of test sites in the High Plains of the Texas Panhandle and in Trans-Pecos Texas. The objectives of producing these maps are: To determine the methodology necessary for developing each type of product. To designate the size, scale, level of detail, and final format of each map within an initial phase of development of remote sensing products. The map products and data analysis procedures described here are based on: Objectives outlined in the Applications System Verification and Transfer (ASVT) Project Plan (McCulloch and McKain, 1978). State agency information needs and listings of possible products developed in conjunction with the User Advisory Group. The Remote Sensing Information Subsystem (RSIS) Level I Design and Design Review documents. The descriptions contained herein are primarily conceptual and are derived from limited hands-on experience with Landsat imagery and digital image processing hardware and software. Analysis of the High Plains region will make maximum use of experience gained in the coastal test site using ISOCLS for unsupervised classification of land cover/land use. The image enhancement techniques to be used for geologic applications in the Trans-Pecos region have not previously been applied as part of RSIS.Bureau of Economic Geolog

Data Collection Plan For Geological Remote Sensing in the Volcanic Terrain of Trans-Pecos Texas, ASVT Test Site 5

This document describes a ground and aircraft data collection plan to be carried out as part of the Texas Applications System Verification and Transfer (ASVT) Project, which is a joint effort of the Texas Natural Resources Information System (TNRIS) Task Force and the National Aeronautics and Space Administration (NASA). The Texas Department of Water Resources/TNRIS has contracted with the Bureau of Economic Geology for the preparation of this Data Collection Plan (DCP), to be initially implemented during the period June-August 1980 as described herein. This DCP applies to a test site in the Trans-Pecos region of Texas, one of five designated test sites within the state. Previously, a ground data collection plan had been prepared for the coastal test site (Finley, 1978), and a plan is in preparation for the High Plains test site.Bureau of Economic Geolog

Annotated Bibliography of Techniques for Image Enhancement and Interpretation in Remote Sensing

The purpose of this annotated bibliography is to provide the user of the Remote Sensing Information Subsystem (RSIS) with brief descriptions of recent research techniques of image enhancement and their applications to specific image interpretation problems. Table 2 of the May 1979 ASVT/RSIS Technical Report entitled "Functional Design Narrative Descriptions" listed digital image processing requirements of the RSIS. The references in this bibliography were chosen because they describe these processing requirements. The format of that table was modified slightly and used as the outline for Section One of this bibliography. The bibliography is not intended to be an exhaustive compilation of all pertinent articles. Such a collection would be outdated as soon as it was printed. It does, however, contain a broad sampling of the recent remote sensing literature. We tried not to include multiple references to the same technique, but some repetition was necessary in order to fully describe some procedures of image enhancement and interpretation.Bureau of Economic Geolog

Outline of Basic Procedures for Remote Sensing Information Subsytem (RSIS) Analysis of Landsat Data

This document outlines basic procedures for analyzing Landsat data using the Remote Sensing Information Subsystem (RSIS), prepared for the Texas Natural Resources Information System and dated November 1980. The outline includes procedures for Reflectance Data Display and Classified Data Display. It provides detailed steps for various tasks such as locating areas of interest, running histogram processors, setting up display tapes, analyzing data, and creating look-up tables. Additionally, it covers the use of software tools like LARSYS Histogram Processor, ISOCLS Processor, and CLRTAB. The document includes tables and figures illustrating channel data, radiance values, and color assignments. It also includes appendices detailing RSIS runstreams and ISOCLS procedures. Overall, it's a comprehensive guide for utilizing RSIS to analyze Landsat data for various applications related to natural resource management and geology.Bureau of Economic Geolog

Plan for Economic Evaluation of Products from the Remote Sensing Information Subsystem (RSIS)

The objective of this proposed analysis is to compare the cost and accuracy of map production using existing methods with map production using the Remote Sensing Information Subsystem (RSIS). Both methods require surface visits in order to control the validity of interpretations. Existing methods imply the use of aerial photography at appropriate scales with conventional photo interpretation techniques. Map units are delineated directly on the photograph, on an overlay, or a map base and, through the process of scribing and other cartographic techniques, a final map product is produced. Use of the RSIS implies the use of Landsat or airborne multispectral scanner data in a digital processing system which will operate in an interactive manner with the interpreter, supplemented by aerial photography. A keyboard cathode ray tube (KCRT) will be the primary means for data display and for the interpreter to direct further data analysis. During the TNRIS/NASA Joint Project, hard-copy output from digital data is dependent upon the use of a Matrix Color Camera to produce Polaroid prints and film transparencies. The RSIS will accept hard-copy input (maps and aerial photographs) for use with overlay production but will not digitize photography.Bureau of Economic Geolog