Showing papers in "Publications of the Astronomical Society of the Pacific in 2011"

The 10 Meter South Pole Telescope

Abstract: .The South Pole Telescope (SPT) is a 10 m diameter, wide-field, offset Gregorian telescope with a 966 pixel, multicolor, millimeter-wave, bolometer camera. It is located at the Amundsen-Scott South Pole station in Antarctica. The design of the SPT emphasizes careful control of spillover and scattering, to minimize noise and false signals due to ground pickup. The key initial project is a large-area survey at wavelengths of 3, 2, and 1.3 mm, to detect clusters of galaxies via the Sunyaev-Zel’dovich effect and to measure the small-scale angular power spectrum of the cosmic microwave background (CMB). The data will be used to characterize the primordial matter power spectrum and to place constraints on the equation of state of dark energy. A second-generation camera will measure the polarization of the CMB, potentially leading to constraints on the neutrino mass and the energy scale of inflation.

The Exoplanet Orbit Database

Abstract: We present a database of well-determined orbital parameters of exoplanets, and their host stars’ properties. This database comprises spectroscopic orbital elements measured for 427 planets orbiting 363 stars from radial velocity and transit measurements as reported in the literature. We have also compiled fundamental transit parameters, stellar parameters, and the method used for the planets discovery. This Exoplanet Orbit Database includes all planets with robust, well measured orbital parameters reported in peer-reviewed articles. The database is available in a searchable, filterable, and sortable form online through the Exoplanets Data Explorer table, and the data can be plotted and explored through the Exoplanet Data Explorer plotter. We use the Data Explorer to generate publication-ready plots, giving three examples of the signatures of exoplanet migration and dynamical evolution: We illustrate the character of the apparent correlation between mass and period in exoplanet orbits, the different selection biases between radial velocity and transit surveys, and that the multiplanet systems show a distinct semimajor-axis distribution from apparently singleton systems.

KINGFISH—Key Insights on Nearby Galaxies: A Far-Infrared Survey with Herschel: Survey Description and Image Atlas

Abstract: The KINGFISH project (Key Insights on Nearby Galaxies: a Far-Infrared Survey with Herschel) is an imaging and spectroscopic survey of 61 nearby (d < 30 Mpc) galaxies, chosen to cover a wide range of galaxy properties and local interstellar medium (ISM) environments found in the nearby universe. Its broad goals are to characterize the ISM of present-day galaxies, the heating and cooling of their gaseous and dust components, and to better understand the physical processes linking star formation and the ISM. KINGFISH is a direct descendant of the Spitzer Infrared Nearby Galaxies Survey (SINGS), which produced complete Spitzer imaging and spectroscopic mapping and a comprehensive set of multiwavelength ancillary observations for the sample. The Herschel imaging consists of complete maps for the galaxies at 70, 100, 160, 250, 350, and 500 μm. The spectral line imaging of the principal atomic ISM cooling lines ([O I] 63 μm, [O III] 88 μm, [N II] 122,205 μm, and [C II] 158 μm) covers the subregions in the centers and disks that already have been mapped in the mid-infrared with Spitzer. The KINGFISH and SINGS multiwavelength data sets combined provide panchromatic mapping of the galaxies sufficient to resolve individual star-forming regions, and tracing the important heating and cooling channels of the ISM, across a wide range of local extragalactic ISM environments. This article summarizes the scientific strategy for KINGFISH, the properties of the galaxy sample, the observing strategy, and data processing and products. It also presents a combined Spitzer and Herschel image atlas for the KINGFISH galaxies, covering the wavelength range 3.6–500 μm. All imaging and spectroscopy data products will be released to the Herschel user-generated product archives.

Common-resolution convolution kernels for space- and ground-based telescopes

Abstract: Multiwavelength study of extended astronomical objects requires combining images from instruments with differing point-spread functions (PSFs). We describe the construction of convolution kernels that allow one to generate (multiwavelength) images with a common PSF, thus preserving the colors of the astronomical sources. We generate convolution kernels for the cameras of Spitzer, Herschel Space Observatory, Galaxy Evolution Explorer (GALEX), Wide-field Infrared Survey Explorer (WISE), ground-based optical telescopes (Moffat functions and sum of Gaussians), and Gaussian PSFs. Kernels for other telescopes including IRAS, AKARI, and Planck, are currently being constructed. These kernels allow the study of the spectral energy distribution (SED) of extended objects, preserving the characteristic SED in each pixel. The convolution kernels and the IDL packages used to construct and use them are made publicly available.

DiFX-2: A More Flexible, Efficient, Robust, and Powerful Software Correlator

Abstract: Software correlation, where a correlation algorithm written in a high-level language such as C++ is run on commodity computer hardware, has become increasingly attractive for small- to medium-sized and/or bandwidth-constrained radio interferometers. In particular, many long-baseline arrays (which typically have fewer than 20 elements and are restricted in observing bandwidth by costly recording hardware and media) have utilized software correlators for rapid, cost-effective, correlator upgrades to allow compatibility with new, wider-bandwidth, recording systems and to improve correlator flexibility. The DiFX correlator, made publicly available in 2007, has been a popular choice in such upgrades and is now used for production correlation by a number of observatories and research groups worldwide. Here, we describe the evolution in the capabilities of the DiFX correlator over the past three years, including a number of new capabilities, substantial performance improvements, and a large amount of supporting infrastructure to ease use of the code. New capabilities include the ability to correlate a large number of phase centers in a single correlation pass, the extraction of phase-calibration tones, correlation of disparate but overlapping sub-bands, the production of rapidly sampled filter-bank and kurtosis data at minimal cost, and many more. The latest version of the code is at least 15% faster than the original (and in certain situations, many times this value). Finally, we also present detailed test results validating the correctness of the new code.

Water in star-forming regions with the Herschel Space Observatory (WISH). I. Overview of key program and first results

Abstract: Water In Star-forming regions with Herschel (WISH) is a key program on the Herschel Space Observatory designed to probe the physical and chemical structures of young stellar objects using water and related molecules and to follow the water abundance from collapsing clouds to planet-forming disks. About 80 sources are targeted, covering a wide ranee of luminosities-from low ( 10(5) L-circle dot)-and a wide range of evolutionary stages-from cold prestellar cores to warm protostellar envelopes and outflows to disks around young stars. Both the HIFI and PACS instruments are used to observe a variety of lines of H2O, (H2O)-O-18 and chemically related species at the source position and in small maps around the protostars and selected outflow positions. In addition, high-frequency lines of CO, (CO)-C-13, and (CO)-O-18 are obtained with Herschel and are complemented by ground-based observations of dust continuum, HDO, CO and its isotopologs, and other molecules to ensure a self-consistent data set for analysis. An overview of the scientific motivation and observational strategy of the program is given, together with the modeling approach and analysis tools that have been developed. Initial science results are presented. These include a lack of water in cold gas at abundances that are lower than most predictions, strong water emission from shocks in protostellar environments, the importance of UV radiation in heating the gas along outflow walls across the full range of luminosities, and surprisingly widespread detection of the chemically related hydrides OH+ and H2O+ in outflows and foreground gas. Quantitative estimates of the energy budget indicate that H2O is generally not the dominant coolant in the warm dense gas associated with protostars. Very deep limits on the cold gaseous water reservoir in the outer regions of protoplanetary disks are obtained that have profound implications for our understanding of grain growth and mixing in disks.

IMACS: The Inamori-Magellan Areal Camera and Spectrograph on Magellan-Baade

Abstract: The Inamori-Magellan Areal Camera and Spectrograph (IMACS) is a wide-field, multipurpose imaging spectrograph on the Magellan-Baade telescope at Las Campanas Observatory. IMACS has two channels—f/2 and f/4, each with an 8K × 8K pixel mosaic of CCD detectors, that service the widest range of capabilities of any major spectrograph. These include wide-field imaging at two scales, 0.20'' pixel-1 and 0.11'' pixel-1, single-object and multislit spectroscopy, integral-field spectroscopy with two 5'' × 7'' areas sampled at 0.20'' pixel-1 (Durham IFU), a multiobject echelle (MOE) capable of N ~ 10 simultaneous full-wavelength R ≈ 20,000 spectra, the Maryland-Magellan Tunable Filter (MMTF), and an image-slicing reformatter for dense-pack multislit work (GISMO). Spectral resolutions of 8 < R < 5000 are available through a combination of prisms, grisms, and gratings, and most modes are instantly available in any given IMACS configuration. IMACS has a spectroscopic efficiency over 50% in f/2 multislit mode (instrument only) and, by the AΩ figure of merit (telescope primary surface area times instrument field of view ), IMACS scores 5.7 m2 deg2, compared with 3.1 for VIMOS on VLT3 and with 2.0 for DEIMOS on Keck2. IMACS is the most versatile, and—for wide-field optical spectroscopy—the most powerful spectrograph on the planet.

A New High Contrast Imaging Program at Palomar Observatory

Abstract: We describe a new instrument that forms the core of a long-term high contrast imaging program at the 200 inch (5 m) Hale Telescope at Palomar Observatory. The primary scientific thrust is to obtain images and low-resolution spectroscopy of brown dwarfs and young exoplanets of several Jupiter masses in the vicinity of stars within 50 pc of the Sun. The instrument is a microlens-based integral field spectrograph integrated with a diffraction-limited, apodized-pupil Lyot coronagraph. The entire combination is mounted behind the Palomar adaptive optics (AO) system. The spectrograph obtains imaging in 23 channels across the J and H bands (1.06–1.78 μm). The image plane of our spectrograph is subdivided by a 200 × 200 element microlens array with a plate scale of 19.2 mas per microlens, critically sampling the diffraction-limited point-spread function at 1.06 μm. In addition to obtaining spectra, this wavelength resolution allows suppression of the chromatically dependent speckle noise, which we describe. In addition, we have recently installed a novel internal wave front calibration system that will provide continuous updates to the AO system every 0.5–1.0 minutes by sensing the wave front within the coronagraph. The Palomar AO system is undergoing an upgrade to a much higher order AO system (PALM-3000): a 3388-actuator tweeter deformable mirror working together with the existing 241-actuator mirror. This system, the highest-resolution AO corrector of its kind, will allow correction with subapertures as small as 8.1 cm at the telescope pupil using natural guide stars. The coronagraph alone has achieved an initial dynamic range in the H band of 2 × 10^(-4) at 1″, without speckle noise suppression. We demonstrate that spectral speckle suppression provides a factor of 10–20 improvement over this, bringing our current contrast at 1″ to ~2 × 10^(-5). This system is the first of a new generation of apodized-pupil coronagraphs combined with high-order adaptive optics and integral field spectrographs (e.g., GPI, SPHERE, HiCIAO), and we anticipate that this instrument will make a lasting contribution to high-contrast imaging in the Northern Hemisphere for years.

Astrometry and Photometry with HST WFC3. II. Improved Geometric-Distortion Corrections for 10 Filters of the UVIS Channel*

Abstract: We present an improved geometric-distortion solution for the Hubble Space Telescope UVIS chan- nel of Wide Field Camera 3 for 10 broadband filters. The solution is made up of three parts: (1) a third-order polynomial to deal with the general optical distortion, (2) a table of residuals that accounts for both chip-related anomalies and fine-structure introduced by the filter, and (3) a linear transformation to put the two chips into a convenient master frame. The final correction is better than 0.008 pixel (∼0:3 mas) in each coordinate. We pro- vide the solution in two different forms: a FORTRAN subroutine and a set of FITS files, one for each filter/chip/ coordinate.

SYNAPPS: Data-Driven Analysis for Supernova Spectroscopy

Abstract: We introduce a new computer program, SYNAPPS, for forward-modeling of supernova (SN) spectroscopy data sets. SYNAPPS is a spectrum fitter embedding a highly parameterized synthetic SN spectrum calculation within a parallel asynchronous optimizer. This open-source code is primarily aimed at the problem of systematically interpreting large sets of SN spectroscopy data. While SYNAPPS should be useful to current SN spectroscopy efforts like the Nearby Supernova Factory, Lick Observatory Supernova Search, Palomar Transient Factory, Harvard Center for Astrophysics SN program, and so on, it could also benefit future similar efforts connected to the Dark Energy Survey, Panoramic Survey Telescope and Rapid Response System, or the Large Synoptic Survey Telescope. Smaller programs are also potential users. SYNAPPS illustrates the potential for data-driven discovery enabled by high-performance computing, where complex physical systems are directly constrained by large information-rich sets of scientific observations. Here, we discuss the motivation of our approach, outline the structure of the code, present some example calculations, and describe a few enhancements in terms of physics modeling, optimization, and computing that we will be pursuing for the future.

Median Statistics and the Hubble Constant

Abstract: .Following Gott et al., we use Huchra’s final compilation of 553 measurements of the Hubble constant (H0H0) to estimate median statistical constraints on H0H0. Our median statistical analysis yields H0 = 68 ± 5.5H0=68±5.5 (or ± 1±1) km s-1 Mpc-1km s-1 Mpc-1, where the errors are the 95% statistical and systematic (or statistical) errors. These results are close to what Gott et al. found a decade ago, with smaller statistical errors and similar systematic errors. With about two-thirds more measurements, we are also able to clearly illustrate the presence and magnitude of systematic errors for different methods.

An Early Warning System for Asteroid Impact

Abstract: Earth is bombarded by meteors, occasionally by one large enough to cause a significant explosion and possible loss of life. It is not possible to detect all hazardous asteroids, and the efforts to detect them years before they strike are only advancing slowly. Similarly, ideas for mitigation of the danger from an impact by moving the asteroid are in their infancy. Although the odds of a deadly asteroid strike in the next century are low, the most likely impact is by a relatively small asteroid, and we suggest that the best mitigation strategy in the near term is simply to move people out of the way. With enough warning, a small asteroid impact should not cause loss of life, and even portable property might be preserved. We describe an early warning system that could provide a week's notice of most sizeable asteroids or comets on track to hit the Earth. This may be all the mitigation needed or desired for small asteroids, and it can be implemented immediately for relatively low cost. This system, dubbed Asteroid Terrestrial-Impact Last Alert System (ATLAS), comprises two observatories separated by about 100 km that simultaneously scan the visible sky twice a night. Software automatically registers a comparison with the unchanging sky and identifies everything that has moved or changed. Communications between the observatories lock down the orbits of anything approaching the Earth, within one night if its arrival is less than a week. The sensitivity of the system permits detection of 140 m asteroids (100 Mton impact energy) three weeks before impact and 50 m asteroids a week before arrival. An ATLAS alarm, augmented by other observations, should result in a determination of impact location and time that is accurate to a few kilometers and a few seconds. In addition to detecting and warning of approaching asteroids, ATLAS will continuously monitor the changing universe around us: most of the variable stars in our Galaxy, many microlensing events from stellar alignments, luminous stars and novae in nearby galaxies, thousands of supernovae, nearly a million quasars and active galactic nuclei, tens of millions of galaxies, and a billion stars. With two views per day ATLAS will make the variable universe as familiar to us as the sunrise and sunset.

WASP-41b: A transiting hot jupiter planet orbiting a magnetically active G8V star

Abstract: .We report the discovery of a transiting planet with an orbital period of 3.05 days orbiting the star TYC 7247-587-1. The star, WASP-41, is a moderately bright G8 VV star (V = 11.6V=11.6) with a metallicity close to solar ([Fe/H] = -0.08 ± 0.09[Fe/H]=-0.08±0.09). The star shows evidence of moderate chromospheric activity, both from emission in the cores of the Ca ii H and K ines and photometric variability with a period of 18.4 days and an amplitude of about 1%. We use a new method to show quantitatively that this periodic signal has a low false-alarm probability. The rotation period of the star implies a gyrochronological age for WASP-41 of 1.8 Gyr with an error of about 15%. We have used a combined analysis of the available photometric and spectroscopic data to derive the mass and radius of the planet (0.92 ± 0.06 MJup0.92±0.06 MJup, 1.20 ± 0.06 RJup1.20±0.06 RJup). Further observations of WASP-41 can be used to explore the connections between the properties of hot Jupiter planets and the leve...

The Ohio State Multi-Object Spectrograph

Abstract: The Ohio State Multi-Object Spectrograph (OSMOS) is a new, wide-field imager and multi-object spectrograph for the 2.4-m Hiltner Telescope at the MDM Observatory. OSMOS has an all-refractive design that reimages a 20 arcminute diameter field-of- view onto the 4064x4064 MDM4K CCD with a plate scale of 0.273 arcseconds per pixel. Approximately an 18.5 ' square region of this field illuminates the detector and is available for spectroscopy, although with reduced wavelength coverage near the edges of the field. Slit masks, filters, and dispersers are all mounted in a series of six-position aperture wheels. These mechanisms rotate between positions in only a few seconds and consequently the instrument may be rapidly reconfigured between imaging and spectroscopic modes. At present a low-resolution triple prism (R � 60 400) and a moderate resolution VPH grism (R � 1600) are available.

SkyMapper Filter Set: Design and Fabrication of Large-Scale Optical Filters

Abstract: .The SkyMapper Southern Sky Survey will be conducted from Siding Spring Observatory with uu, vv, gg, rr, ii, and zz filters that comprise glued glass combination filters with dimensions of 309 × 309 × 15 mm309×309×15 mm. In this article we discuss the rationale for our bandpasses and physical characteristics of the filter set. The uu, vv, gg, and zz filters are entirely glass filters, which provide highly uniform bandpasses across the complete filter aperture. The ii filter uses glass with a short-wave pass coating, and the rr filter is a complete dielectric filter. We describe the process by which the filters were constructed, including the processes used to obtain uniform dielectric coatings and optimized narrowband antireflection coatings, as well as the technique of gluing the large glass pieces together after coating using UV transparent epoxy cement. The measured passbands, including extinction and CCD QE, are presented.

Toward Precision LSST Weak-Lensing Measurement. I. Impacts of Atmospheric Turbulence and Optical Aberration

Abstract: The weak-lensing science of the Large Synoptic Survey Telescope (LSST) project drives the need to carefully model and separate the instrumental artifacts from the intrinsic shear signal caused by gravitational lensing. The dominant source of the systematics for all ground-based telescopes is the spatial correlation of the point-spread function (PSF) modulated by both atmospheric turbulence and optical aberrations in the telescope and camera system. In this article, we present a full field-of-view simulation of the LSST images by modeling both the atmosphere and the system optics with the most current data for the telescope and camera specifications and the environment. To simulate the effects of atmospheric turbulence, we generated six-layer Kolmogorov/von Karman phase screens with the parameters estimated from the on-site measurements. LSST will continuously sample the wavefront, correcting the optics alignment and focus. For the optics, we combined the ray-tracing tool ZEMAX and our simulated focal-plane data to introduce realistic residual aberrations and focal-plane height variations. Although this expected focal-plane flatness deviation for LSST is small compared with that of other existing cameras, the fast focal ratio of the LSST optics cause this focal-plane flatness variation and the resulting PSF discontinuities across the CCD boundaries to be significant challenges in our removal of the PSF-induced systematics. We resolve this complication by performing principal component analysis (PCA) CCD by CCD and by interpolating the basis functions derived from the analysis using conventional polynomials. We demonstrate that this PSF correction scheme reduces the residual PSF ellipticity correlation below 10-7 over the cosmologically interesting (dark-matter-dominated) scale 10'-3°. From a null test using the Hubble Space Telescope (HST) Ultra Deep Field (UDF) galaxy images without input shear, we verify that the amplitude of the galaxy ellipticity correlation function, after the PSF correction, is consistent with the shot noise set by the finite number of objects. We conclude that the current optical design and specification for the accuracy in the focal-plane assembly are sufficient to enable the control of the PSF systematics required for weak-lensing science with LSST.

Single-Dish Performance of KVN 21 m Radio Telescopes: Simultaneous Observations at 22 and 43 GHz

Abstract: We report simultaneous multifrequency observing performance at 22 and 43 GHz of the 21 m shaped-Cassegrain radio telescopes of the Korean VLBI Network (KVN). KVN is the first millimeter-dedicated VLBI network in Korea having a maximum baseline length of 480 km. It currently operates at 22 and 43 GHz and is planned to operate in four frequency bands: 22, 43, 86, and 129 GHz. The unique quasi optics of KVN enable simultaneous multifrequency observations based on efficient beam filtering and accurate antenna-beam alignment at 22 and 43 GHz. We found that the offset of the beams is within less than 5'' over all pointing directions of the antenna. The dual-polarization, cooled, high electron mobility transistor (HEMT) receivers at 22 and 43 GHz result in receiver noise temperatures less than 40 K at 21.25-23.25 GHz and 80 K at 42.11-44.11 GHz. The pointing accuracies have been measured to be 3'' in azimuth and elevation for all antennas. The measured aperture efficiencies are 65%(K)/67%(Q), 62%(K)/59%(Q), and 66%(K)/60%(Q) for the three KVN antennas, KVNYS, KVNUS, and KVNTN, respectively. The main-beam efficiencies are measured to be 50%(K)/52%(Q), 48%(K)/50%(Q), and 50%(K)/47%(Q) for KVNYS, KVNUS, and KVNTN, respectively. The estimated Moon efficiencies are 77%(K)/90%(Q), 74%(K)/79%(Q), and 80%(K)/86%(Q) for KVNYS, KVNUS, and KVNTN, respectively. The elevation dependence of the aperture efficiencies is quite flat for elevations greater than 20°.

The Pan-STARRS Synthetic Solar System Model: A Tool for Testing and Efficiency Determination of the Moving Object Processing System

Abstract: We present here the Pan-STARRS Moving Object Processing System (MOPS) Synthetic Solar System Model (S3M), the first-ever attempt at building a comprehensive flux-limited model of the major small-body populations in the solar system. The goal of the S3M is to provide a valuable tool in the design and testing of the MOPS software, and will be used in the monitoring of the upcoming Pan-STARRS 1 all-sky survey, which started science operations during late spring of 2010. The model is composed of synthetic populations of near-Earth objects (NEOs with a subpopulation of Earth impactors), the main-belt asteroids (MBAs), Jovian Trojans, Centaurs, trans-Neptunian objects (classical, resonant, and scattered trans-Neptunian objects [TNOs]), Jupiter-family comets (JFCs), long-period comets (LPCs), and interstellar comets. The model reasonably reproduces the true populations to a minimum of V = 24.5, corresponding to approximately the expected limiting magnitude for Pan-STARRS's ability to detect moving objects. The NEO synthetic population has been extended to H < 25 (corresponding to objects of about 50 m in diameter), allowing for close flybys of the Earth to be modeled.

Experimental Design for the Gemini Planet Imager

Abstract: The Gemini Planet Imager (GPI) is a high-performance adaptive optics system being designed and built for the Gemini Observatory. GPI is optimized for high-contrast imaging, combining precise and accurate wavefront control, diffraction suppression, and a speckle-suppressing science camera with integral field and polarimetry capabilities. The primary science goal for GPI is the direct detection and characterization of young, Jovian-mass exoplanets. For plausible assumptions about the distribution of gas giant properties at large semimajor axes, GPI will be capable of detecting more than 10% of gas giants more massive than 0.5 MJ around stars younger than 100 Myr and nearer than 75 pc. For systems younger than 1 Gyr, gas giants more massive than 8 MJ and with semimajor axes greater than 15 AU are detected with completeness greater than 50%. A survey targeting young stars in the solar neighborhood will help determine the formation mechanism of gas giant planets by studying them at ages where planet brightness depends upon formation mechanism. Such a survey will also be sensitive to planets at semimajor axes, comparable with the gas giants in our own solar system. In the simple, and idealized, situation in which planets formed by either the "hot-start" model of Burrows et al. or the core accretion model of Marley et al., a few tens of detected planets are sufficient to distinguish how planets form.

Hectochelle: A Multiobject Optical Echelle Spectrograph for the MMT

Abstract: .The Hectochelle is an optical band, fiber-fed, multiobject echelle spectrograph deployed at the MMT Observatory on Mount Hopkins, Arizona. The optical fibers that feed the Hectochelle are positioned by the Hectospec robot positioner on the MMT f/5 focal surface, and the Hectochelle shares an optical fiber feed system with the Hectospec, a moderate-dispersion spectrograph that is collocated with the Hectochelle. Hectochelle can record up to 240 spectra simultaneously at a resolution of 38,000. Spectra cover a single diffractive order that is approximately 150 A wide. The total potential operating passband of the Hectochelle extends from 3800 A to 9000 A. Operated in conjunction with the MMT f/5 secondary, the MMT wide-field corrector, and the atmospheric dispersion compensator, the patrol field is 1° in diameter and the individual fiber slits are 1.5′′ in diameter. The throughput of the combined telescope, fiber feed, and spectrograph is measured to be 6.1% at 5275 A, exclusive of atmospheric exti...

SpecPro: An Interactive IDL Program for Viewing and Analyzing Astronomical Spectra

Abstract: We present an interactive IDL program for viewing and analyzing astronomical spectra in the con- text of modern imaging surveys. SpecPro's interactive design lets the user simultaneously view spectroscopic, photometric, and imaging data, allowing for rapid object classification and redshift determination. The spectro- scopic redshift can be determined with automated cross-correlation against a variety of spectral templates or by manually overlaying common emission and absorption features on the 1-D and 2-D spectra. Stamp images and the spectral energy distribution (SED) of a source can be displayed with the interface, with the positions of pro- minent photometric features indicated on the SED plot. Results can easily be saved to file from within the interface. In this article we briefly discuss key interface features and provide an overview of the data formats required by the program.

Astronomy with Radioactivities

Abstract: Part I The Role of Radioactivities in Astrophysics.- Introduction to Astronomy With Radioactivity.- The Role of Radioactive Isotopes in Astrophysics.- Part II Specific Sources of Cosmic Isotopes.- Radioactivities in Low-and Intermediate-Mass Stars.- Massive Stars and their Supernovae.- Binary Systems and Their Nuclear Explosions.- Part III Special Places to Observe Cosmic Isotopes.- Distributed Radioactivities.- Part IV Tools for the Study of Radioactivities in Astrophysics.- Nuclear Reactions.- Instruments for Observations of Radioactivities.- Part V Epilogue.- Perspectives.- Annotations on Chemical Evolution.- Radionuclides and Their Stellar Origins.- Milestones in the Science of Cosmic Radioactivities.- Glossary: Key Terms in Astronomy With Radioactivities.- Index.

Astronomy in the Cloud: Using MapReduce for Image Co-Addition

Abstract: In the coming decade, astronomical surveys of the sky will generate tens of terabytes of images and detect hundreds of millions of sources every night. The study of these sources will involve computation challenges such as anomaly detection and classification and moving-object tracking. Since such studies benefit from the highest-quality data, methods such as image co-addition, i.e., astrometric registration followed by per-pixel summation, will be a critical preprocessing step prior to scientific investigation. With a requirement that these images be analyzed on a nightly basis to identify moving sources such as potentially hazardous asteroids or transient objects such as supernovae, these data streams present many computational challenges. Given the quantity of data involved, the computational load of these problems can only be addressed by distributing the workload over a large number of nodes. However, the high data throughput demanded by these applications may present scalability challenges for certain storage architectures. One scalable data-processing method that has emerged in recent years is MapReduce, and in this article we focus on its popular open-source implementation called Hadoop. In the Hadoop framework, the data are partitioned among storage attached directly to worker nodes, and the processing workload is scheduled in parallel on the nodes that contain the required input data. A further motivation for using Hadoop is that it allows us to exploit cloud computing resources: i.e., platforms where Hadoop is offered as a service. We report on our experience of implementing a scalable image-processing pipeline for the SDSS imaging database using Hadoop. This multiterabyte imaging data set provides a good testbed for algorithm development, since its scope and structure approximate future surveys. First, we describe MapReduce and how we adapted image co-addition to the MapReduce framework. Then we describe a number of optimizations to our basic approach and report experimental results comparing their performance.

Grids of ATLAS9 Model Atmospheres and MOOG Synthetic Spectra

Abstract: A grid of ATLAS9 model atmospheres has been computed, spanning 3500 K ≤ T_(eff) ≤ 8000 K, 0.0 ≤ log g ≤ 5.0, -4.0 ≤ [M/H] ≤ 0.0, and -0.8 ≤ [α/Fe] ≤ +1.2. These parameters are appropriate for old stars in the red giant branch, subgiant branch, and the lower main sequence. The main difference from a previous similar grid is the range of [α/Fe] values. A grid of synthetic spectra, calculated from the model atmospheres, is also presented. The fluxes are computed every 0.02 Å from 6300 Å to 9100 Å. The microturbulent velocity is given by a relation to the surface gravity. This relation is appropriate for red giants, but not for subgiants or dwarfs. Therefore, caution is urged for the synthetic spectra with log g > 3.5 or for any star that is not a red giant. Both the model atmosphere and synthetic spectrum grids are available online through VizieR. Applications of these grids include abundance analysis for large samples of stellar spectra and constructing composite spectra for stellar populations.

European Extremely Large Telescope Site Characterization I: Overview

Abstract: .The site for the future European Extremely Large Telescope (E-ELT) is already known to be Armazones, near Paranal (Chile). The selection was based on a variety of considerations, with an important one being the quality of the atmosphere for the astronomy planned for the ELT. We present an overview of the characterization of the atmospheric parameters of candidate sites, making use of standard procedures and instruments as carried out within the Framework Programme VI (FP6) of the European Union. We have achieved full characterization of the selected sites for the parameters considered. Further details on adaptive optics results and climatology will be the subject of two forthcoming articles. A summary of the results of the FP6 site-testing campaigns at the different sites is provided.

Calibration and Performance of the Photon-counting Detectors for the Ultraviolet Imaging Telescope (UVIT) of the Astrosat Observatory*

Abstract: We describe calibration data and discuss performance of the photon-counting flight detectors for the Ultraviolet Imaging Telescopes on the Astrosat observatory. This article describes dark current, flat-field, and light-spot images for FUV, NUV, and visible band detectors at more than one wavelength setting for each. We also report on nominal-gain and low-gain operations, full- and subwindow read rates, and non-photon-counting modes of operation, all expected to be used in flight. We derive corrections to the event centroids from the CMOS readout arrays, for different centroid algorithms. We derive spatial resolution values for each detector and plots of point- source signal saturation for different flux levels. We also discuss ways to correct for saturation in extended object images.

Ground-Based Submillimagnitude CCD Photometry of Bright Stars Using Snapshot Observations

Abstract: We demonstrate ground-based submillimagnitude ( 107 e-) to be acquired in a single integration, (3) pointing the telescope so that all stellar images fall on the same detector pixels, and (4) using a region of the CCD detector that is free of nonlinear or aberrant pixels. We describe semiautomated observations with the Supernova Integrated Field Spectrograph (SNIFS) on the University of Hawaii 2.2 m telescope on Mauna Kea, with which we achieved photometric precision as good as 5.2 × 10-4 (0.56 mmag) with a 5 minute cadence over a 2 hr interval. In one experiment, we monitored eight stars, each separated by several degrees, and achieved submillimagnitude precision with a cadence (per star) of ~17 minutes. Our snapshot technique is suitable for automated searches for planetary transits among multiple bright stars.

First results from the MIT optical rapid imaging system (MORIS) on the IRTF: A stellar occultation by Pluto and a transit by exoplanet XO-2b

Abstract: We present a high-speed, visible-wavelength imaging instrument: MORIS (the MIT Optical Rapid Imaging System). MORIS is mounted on the 3 m Infrared Telescope Facility (IRTF) on Mauna Kea, Hawaii. Its primary component is an Andor iXon camera, a nearly 60" square field of view with high quantum efficiency, low read noise, low dark current, and full-frame readout rates ranging from as slow as desired to a maximum of between 3.5 Hz and 35 Hz (depending on the mode; read noise of 6 e- pixel-1 and 49 e- pixel-1 with electron-multiplying gain = 1, respectively). User-selectable binning and subframing can increase the cadence to a few hundred hertz. An electron-multiplying mode can be employed for photon counting, effectively reducing the read noise to subelectron levels at the expense of dynamic range. Data cubes, or individual frames, can be triggered to several-nanosecond accuracy using the Global Positioning System. MORIS is mounted on the side-facing exit window of SpeX, allowing simultaneous near-infrared and visible observations. Here, we describe the components, setup, and measured characteristics of MORIS. We also report results from the first science observations: the 2008 June 24 stellar occultation by Pluto and an extrasolar planetary transit by XO-2b. The Pluto occultation of a 15.8R magnitude star has a signal-to-noise ratio of 35 per atmospheric scale height and a midtime error of 0.32 s. The XO-2b transit reaches photometric precision of 0.5 mmag in 2 minutes and has a midtime timing precision of 23 s.

A Data-Cube Extraction Pipeline for a Coronagraphic Integral Field Spectrograph

Abstract: Project 1640 is a high-contrast near-infrared instrument probing the vicinities of nearby stars through the unique combination of an integral field spectrograph with a Lyot coronagraph and a high-order adaptive optics system. The extraordinary data-reduction demands, similar to those that several new exoplanet imaging instruments will face in the near future, have been met by the novel software algorithms described herein. The Project 1640 Data Cube Extraction Pipeline (PCXP) automates the translation of 3.8 × 10^4 closely packed, coarsely sampled spectra to a data cube. We implement a robust empirical model of the spectrograph focal-plane geometry to register the detector image at subpixel precision, and we map the cube extraction. We demonstrate our ability to accurately retrieve source spectra based on an observation of Saturn’s moon Titan.

The Role of Planets in Shaping Planetary Nebulae

Abstract: In 1997 Soker laid out a framework for understanding the formation and shaping of planetary nebulae (PN). Starting from the assumption that nonspherical PN cannot be formed by single stars, he linked PN morphologies to the binary mechanisms that may have formed them, basing these connections almost entirely on observational arguments. In light of the last decade of discovery in the field of PN, we revise this framework, which, although simplistic, can still serve as a benchmark against which to test theories of PN origin and shaping. Within the framework, we revisit the role of planets in shaping PN. Soker invoked a planetary role in shaping PN because there are not enough close binaries to shape the large fraction of nonspherical PN. In this article we adopt a model whereby only ~20% of all 1-8 M⊙ stars make a PN. This reduces the need for planetary shaping. Through a propagation of percentages argument, and starting from the assumption that planets can only shape mildly elliptical PN, we conclude that ~20% of all PN were shaped via planetary and other substellar interactions, but we add that this corresponds to only ~5% of all 1-8 M⊙ stars. This may be in line with findings of planets around main-sequence stars. PN shaping by planets is made plausible by the recent discovery of planets that have survived interactions with red giant branch (RGB) stars. Finally, we conclude that of the ~80% of 1-8 M⊙ stars that do not make a PN, about one-quarter do not even ascend the AGB due to interactions with stellar and substellar companions, while three-quarters ascend the AGB but do not make a PN. Once these stars leave the AGB they evolve normally and can be confused with post-RGB, extreme horizontal branch stars. We propose tests to identify them.