The United Kingdom Infrared Telescope (UKIRT) observatory has been transferred to the ownership of the University of Hawaii (UH) and is now being managed by UH. We have established partnerships with several organizations to utilize the UKIRT for science projects and to support its operation. Our main partners are the U.S. Naval Observatory (USNO), the East Asian Observatory (EAO), and the UKIRT microlensing team (JPL/IPAC/OSU/Vanderbilt). The USNO is working on deep northern hemisphere surveys in the H and K bands and the UKIRT microlensing team is running a monitoring campaign of the Galactic bulge. EAO, UH, and USNO have individual P.I. research programs. Most of the observations are using the Wide Field Camera (WFCAM), but the older suite of cassegrain instruments are still fully operational. Data processing and archiving continue to be done CASU and WSA in the UK. We are working on a concept to upgrade the WFCAM with new larger infrared detector arrays for substantially improved survey efficiency.
We present the initial performance test results for the H4RG-10 (A2), the second generation of the H4RG-10 visible CMOS-Hybrid Sensor Chip Assembly (SCA). The first science grade H4RG-10 (A2), delivered in 2009, is an evolution of the first generation A1, first delivered and tested in 2007. The H4RG-10 is primarily intended for
ground- and space-based astronomical applications. Our evaluation focused on the performance parameters as they are related to astrometric applications. We find that the A2 SCA shows high pixel interconnect (99.6%), and low read noise (10-15 e- RMS) when operated at high speeds, consistent with A1 results. Most importantly, the H4RG-10 (A2) shows a dramatic improvement in dark current vs. the A1, with a two order of magnitude reduction in mean
dark level and significantly reduced hot pixel population below 200 K.
We present the results of the Astrophysics Strategic Mission Concept Study for the New Worlds Observer (NWO). We show that the
use of starshades is the most effective and affordable path to mapping and understanding our neighboring planetary systems, to opening
the search for life outside our solar system, while serving the needs of the greater astronomy community. A starshade-based mission
can be implemented immediately with a near term program of technology demonstration.
We present both laboratory and telescope testing results describing the performance of the H4RG-10 CMOS-Hybrid
detector. The H4RG-10 is the largest visible hybrid array currently in existence and shows great potential for use in
future space missions. We report read noise, dark current, pixel connectivity, persistence, and inter-pixel
capacitance measurements for the temperature range 110-240 K. We report on quantitative astrometric and
qualitative photometric performance of the instrument based on observations made at USNO's Flagstaff Station
observatory and establish an upper limit to the astrometric performance of the detector. We discuss additional
testing and future work associated with improving detector performance.
CMOS-based focal planes have many potential advantages over CCDs for use in space for star mapping/star
tracking applications. These include more flexible readout circuitry and improved radiation tolerance. There are
also weaknesses, including noise performance, quantum efficiency, and potential systematics introduced by the
presence of circuitry on the photosensitive side of the detector. In this paper, we measure the effects of these sources
of error on centroiding and photometry for the HDTV (1k x 2k) SI-1920HD camera by observing stellar reference
fields using USNO's 8-inch Twin Astrograph telescope in Flagstaff, AZ. This camera serves as an archetype for the
entire family of related TIS detectors, including the 3k x 4k V12M and the 7.6k x 7.6k V59M. We determine an
upper limit for the astrometric centroiding performance for this class of detector to be ~1/30th of a pixel. There are
indications that better performance may be possible if improvements are made to the temperature control system
used for this first set of observations.
This paper presents the radiometric and noise characteristics of 12-bit SI-1920HD cameras built from the AltaSens ProCamHD 3560 FPA as a function of integration time and temperature. Our measurements are for two integration time regions: 1 to 50 millisecond, which is standard for video operation; and 1 to 240 seconds, of possible use for stellar observations. For 1 to 50 millisecond integration times, the cameras are extremely linear with a Gaussian-like dark frame. As we increased to seconds-long integration times, the camera initially remains radiometrically linear, but develops a dark frame with the vast majority of pixels at dn=5. Further increases in integration time eventually result in a saturated dark frame with all pixels at dn=4095. Reducing the operating temperature to -7.2°C increased the integration times at which the camera's two transitions occur by a factor of 20. The calibration parameters determined from our measurements were applied to the image data collected by Dorland et al. (these proceedings).
A full-wafer, 10,580 × 10,560 pixel (95 × 95 mm) CCD was designed and tested at Semiconductor Technology
Associates (STA) with 9 μm square pixels and 16 outputs. The chip was successfully fabricated in 2006 at DALSA
and some performance results are presented here. This program was funded by the Office of Naval Research
through a Small Business Innovation in Research (SBIR) program requested by the U.S. Naval Observatory for
its next generation astrometric sky survey programs. Using Leach electronics, low read-noise output of the 111
million pixels requires 16 seconds at 0.9 MHz. Alternative electronics developed at STA allow readout at 20
MHz. Some modifications of the design to include anti-blooming features, a larger number of outputs, and use
of p-channel material for space applications are discussed.
The e2v CCD212 was designed and developed explicitly to support very high accuracy astrometric observations in
moderate radiation environments in space. One of the major new innovations in the detector is the use of "charge
canals", i.e. regions of raised potential walls rather than notches or channels, in order to mitigate bulk damage
effects without the CTI discontinuities associated with spilling over the notch capacity. We report on both pre- and
post-radiation performance test results for this detector.
We report on the measurement results for the STA model 1046 CCD, designed to support requirements for USNO's proposed Astrometric Mapping Explorer (AMEX) space astrometry mission. The STA1046 is found to meet AMEX requirements for operating speed, read noise, charge transfer inefficiency (CTI) and dark current after exposure to a high-energy proton fluence of 5 x 109 p+ cm-2 (@63.3 MeV). The lab measurements provide the basis for developing a validated performance model of the STA1046 which we use, along with USNO's Radiation Effects Simulation (RES), to predict on-orbit centroiding performance of an STA1046-based instrument.
We report on the measurement results for two candidate astrometric CCD designs, the STA700 and the e2v CCD43. Both of these CCDs have been considered as design baseline CCDs for use in a high-precision astrometric instrument in space, similar to the one proposed for the FAME, DIVA, or AMEX missions. We have exposed one sample CCD of each design to a fluence of 5 x 109 p+ cm-2 (@ 63.3 MeV), then measured the relevant readout noise, dark current, charge injection noise, and CTI performance. We compare the two CCDs and assess how well each mitigates radiation damage.
High accuracy space astrometry missions such as the recently proposed AMEX will observe tens of millions of stars with mission measurement accuracies of less than 150 microarcseconds at mv = 9. In order to achieve this level of accuracy and coverage, focal planes containing tens of CCDs are necessary. These CCDs are exposed to damage from charged particles from Earth's radiation belts and solar wind. We have developed a computer simulation in order to estimate the effects of charged particle damage on the single measurement precision of an astrometric instrument in space. We describe the simulation in detail, and provide an example of its use in predicting the measurement performance of the AMEX instrument.
We discuss the Ballistic Missile Defense Organization's current system for archiving measurement data from phenomenology missions. We propose a new paradigm for a distributed, interoperable 'virtual' data center that delivers access to measured data, descriptive catalogs, modeling and analysis resources to the user's desktop computer. We discuss requirements and architecture for the first version as well as future enhancements to such a system.
The Backgrounds Data Center (BDC) is the designated archive for backgrounds data collected by Ballistic Missile Defense Organization (BMDO) programs, some of which include ultraviolet sensors. Currently, the BDC holds ultraviolet data from the IBSS, UVPI, UVLIM, and FUVCAM sensors. The BDC will also be the prime archive for Midcourse Space Experiment (MSX) data and is prepared to negotiate with program managers to handle other datasets. The purpose of the BDC is to make data accessible to users and to assist them in analyzing it. The BDC maintains the Science Catalog Information Exchange System (SCIES) allowing remote users to log in, read or post notices about current programs, search the catalogs for datasets of interest, and submit orders for data. On-site facilities are also available for the analysis of data, and consist of VMS and UNIX workstations with access to software analysis packages such as IDL, IRAF, and Khoros. Either on-site or remotely, users can employ the BDC-developed graphical user interface called the Visual Interface for Space and Terrestrial Analysis (VISTA) to generate catalog queries and to display and analyze data. SCIES and VISTA permit nearly complete access to BDC services and capabilities without the need to be physically present at the data center.
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