We have conducted simulations of a memory-efficient up-the-ramp sampling algorithm for infrared detector arrays. Our
simulations use realistic sky models of galaxy brightness, shapes, and distributions, and include the contributions of
zodiacal light and cosmic rays. A simulated readout is based on the HAWAII-2RG arrays, and includes read noise, dark
current, KTC noise, reset anomaly, persistence, and random telegraph noise. The up-the-ramp algorithm rejects cosmic
rays, RTN, and KTC noise. The reset anomaly and persistence are also correctable. It produces a best estimate of the
source flux under the assumption of very low signal-to-noise, while the overall dynamic range is increased. We present
an analysis of the fidelity of image brightness recovery with this algorithm. This work is motivated by the need for
sensitive, precise, accurate photometry for Destiny, a mission concept under study for the Joint Dark Energy Mission
We have developed performance simulations for a precision attitude determination system using a focal plane star
tracker on an infrared space telescope. The telescope is being designed for the Destiny mission to measure
cosmologically distant supernovae as one of the candidate implementations for the Joint Dark Energy Mission. Repeat
observations of the supernovae require attitude control at the level of 0.010 arcseconds (0.05 microradians) during
integrations and at repeat intervals up to and over a year. While absolute accuracy is not required, the repoint precision is
challenging. We have simulated the performance of a focal plane star tracker in a multidimensional parameter space,
including pixel size, read noise, and readout rate. Systematic errors such as proper motion, velocity aberration, and
parallax can be measured and compensated out. Our prediction is that a relative attitude determination accuracy of 0.001
to 0.002 arcseconds (0.005 to 0.010 microradians) will be achievable. Attitude control will have a jitter of around 0.003
arcseconds and stability/repeatability to around 0.002 arcseconds.
We have proposed the development of a low-cost space telescope, Destiny, as a concept for the NASA/DOE
Joint Dark Energy Mission. Destiny is a 1.65m space telescope, featuring a near-infrared (0.85-1.7m) survey
camera/spectrometer with a large flat-field Field Of View (FOV). Destiny will probe the properties of dark
energy by obtaining a Hubble diagram based on Type Ia supernovae (SN) and a large-scale mass power
spectrum derived from weak lensing distortions of field galaxies as a function of redshift.
⪅Destiny is a simple, direct, low cost mission to determine the properties of dark energy by obtaining a cosmologically
deep supernova (SN) type Ia Hubble diagram. Its science instrument is a 1.65m space telescope, featuring a grism-fed
near-infrared (NIR) (0.85-1.7 μm) survey camera/spectrometer with a 0.12 square degree field of view (FOV) covered
by a mosaic of 16 2k x 2k HgCdTe arrays. For maximum operational simplicity and instrument stability, Destiny will be
deployed into a halo-orbit about the Second Sun-Earth Lagrange Point. During its two-year primary mission, Destiny
will detect, observe, and characterize ~3000 SN Ia events over the redshift interval 0.4 < z < 1.7 within a 3 square
degree survey area. In conjunction with ongoing ground-based SN Ia surveys for z < 0.8, Destiny mission data will be
used to construct a high-precision Hubble diagram and thereby constrain the dark energy equation of state. The total
range of redshift is sufficient to explore the expansion history of the Universe from an early time, when it was strongly
matter-dominated, to the present when dark energy dominates. The grism-images will provide a spectral resolution of
R≡λ/Δλ=75 spectrophotometry that will simultaneously provide broad-band photometry, redshifts, and SN
classification, as well as time-resolved diagnostic data, which is valuable for investigating additional SN luminosity
diagnostics. Destiny will be used in its third year as a high resolution, wide-field imager to conduct a multicolor NIR
weak lensing (WL) survey covering 1000 square degrees. The large-scale mass power spectrum derived from weak
lensing distortions of field galaxies as a function of redshift will provide independent and complementary constraints on
the dark energy equation of state. The combination of SN and WL is much more powerful than either technique on its
own. Used together, these surveys will have more than an order of magnitude greater sensitivity (by the Dark Energy
Task Force's (DETF) figure of merit) than will be provided by ongoing ground-based projects. The dark energy
parameters, w0 and wa, will be measured to a precision of 0.05 and 0.2 respectively.
The Destiny space telescope is a candidate architecture for the NASA-DOE Joint Dark Energy Mission (JDEM). This paper describes some of the scientific and observational issues that will be explored as part of our mission concept study. The Destiny ~1.8-meter near-infrared (NIR) grism-mode space telescope would gather a census of type Ia and type II supernovae (SN) over the redshift range 0.5 < z < 1.7 for measuring the expansion rate of the Universe as a function of time and characterizing the nature of dark energy. The central concept is a wide-field, all-grism NIR survey camera. Grism spectra with 2-pixel resolving power R~70-100 will provide broad-band spectrophotometry, redshifts, SN classification, as well as valuable time-resolved diagnostic data for understanding the SN explosion physics. Spectra from all objects within the 1° x 0.25° FOV will be obtained on a large HgCdTe focal plane array. Our methodology requires only a single mode of operation, a single detector technology, and a single instrument.
The Dark Energy Space Telescope (DESTINY) is a proposed approach to the Joint Dark Energy Mission (JDEM). This paper describes its current design and trades of an on-going mission concept study. The DESTINY ~1.8-meter near-infrared (NIR) grism-mode space telescope would gather a census of type Ia and type II supernovae (SN) over the redshift range 0.5<Z<1.7 for characterizing the nature of dark energy. The central concept is a wide-field, all-grism NIR survey camera. Grism spectra with 2-pixel resolving power λ/Δλ≈ 100 will provide broadband spectrophotometry, redshifts, SN classification, as well as valuable time-resolved diagnostic data for understanding the SN explosion physics. DESTINY provides simultaneous spectroscopy on each object within the wide field-of-view sampled by a large focal plane array. The design combines the wide FOV coverage of a flat field, all-reflective three mirror anastigmat with spectroscopy using an optimized nonobjective "objective" grism located in the real exit pupil of the TMA. The spectra from objects within the resulting 0.25 square-degree FOV are sampled with 100 mas pixels by an 8k x 32k HgCdTe FPA. This methodology requires only a single mode of operation, a single detector technology, and a single instrument.
The Galactic Exoplanet Survey Telescope (GEST) will observe a 2 square degree field in the Galactic bulge to search for extra-solar planets using a gravitational lensing technique. This gravitational lensing technique is the only method employing currently available technology that can detect Earth-mass planets at high signal-to-noise, and can measure the abundance of terrestrial planets as a function of Galactic position. GEST's sensitivity extends down to the mass of Mars, and it can detect hundreds of terrestrial planets with semi-major axes ranging from 0.7 AU to infinity. GEST will be the first truly comprehensive survey of the Galaxy for planets like those in our own Solar System.
Application of deconvolution algorithms to astronomical images is often limited by variations in PSF structure over the domain of the images. One major difficulty is that Fourier methods can no longer be used for fast convolutions over the enitre images. However, if the PSF is modeled as a sum of orthogonal functions that are individually constant in form over the images, but whose relative amplitudes encode the PSF spatial variability, then separation of variables again allows global image operations to be used. This approach is readily adapted to the Lucy-Richardson deconvolution algorithm. Use of the Karhunen-Loeve transform allows for a particularly compact orthogonal expansion of the PSF. These techniques are demonstrated on the deconvolution of Gemini/Hokupa'a adaptive optics images of the galactic center.
The NOAO Science Archive (NSA) is a step toward building a comprehensive scientific archive of the optical and infrared data holdings of the National Optical Astronomy Observatory. Earlier efforts included the NOAO Save the Bits archive (more properly a data store) with current raw data holdings from telescopes at both Kitt Peak National Observatory and Cerro Tololo Inter-American Observatory of more than 3 million images, totaling in excess of 20 terabytes. The NOAO Science Archive builds on the foundation provided by the NOAO Deep-Wide Field Survey (NDWFS) Archive that offers sophisticated analysis tools -- as well as the coherent and extensive NDWFS data set. NSA is an initiative of the NOAO Data Products Program aimed at identifying scientifically useful datasets from the large and growing NOAO holdings and making these data available to the astronomical community, while providing tools for data discovery, mining and exploration. The goals for the NSA are: to immediately create a scientifically useful archive of NOAO Survey data, to develop in-house expertise in the relevant technologies, to identify and document requirements for NOAO's future comprehensive archive by providing a design study, and to create a high level of visibility and utility for both the NOAO Archive and NOAO Surveys (for example, with web services available at http://archive.noao.edu). The archive and associated NOAO assets are expected to grow into a resource of the National Virtual Observatory.