2,312 research outputs found
Development of a coaxial plasma gun for space propulsion final report
Current sheet accelerators and pulsed plasma thrustors for spacecraft propulsio
The Spitzer-South Pole Telescope Deep Field: Survey Design and IRAC Catalogs
The Spitzer-South Pole Telescope Deep Field (SSDF) is a wide-area survey
using Spitzer's Infrared Array Camera (IRAC) to cover 94 square degrees of
extragalactic sky, making it the largest IRAC survey completed to date outside
the Milky Way midplane. The SSDF is centered at 23:30,-55:00, in a region that
combines observations spanning a broad wavelength range from numerous
facilities. These include millimeter imaging from the South Pole Telescope,
far-infrared observations from Herschel/SPIRE, X-ray observations from the XMM
XXL survey, near-infrared observations from the VISTA Hemisphere Survey, and
radio-wavelength imaging from the Australia Telescope Compact Array, in a
panchromatic project designed to address major outstanding questions
surrounding galaxy clusters and the baryon budget. Here we describe the
Spitzer/IRAC observations of the SSDF, including the survey design,
observations, processing, source extraction, and publicly available data
products. In particular, we present two band-merged catalogs, one for each of
the two warm IRAC selection bands. They contain roughly 5.5 and 3.7 million
distinct sources, the vast majority of which are galaxies, down to the SSDF
5-sigma sensitivity limits of 19.0 and 18.2 Vega mag (7.0 and 9.4 microJy) at
3.6 and 4.5 microns, respectively.Comment: Accepted by ApJS; this version updated to conform to refereed articl
Going places
Journeys. We all make them. Often they take us to exotic places. Sometimes they take us even further. They might take us through time. Or they might take us into a new way of life. There are times too, when we go all over the world and back again only to find that home is, after all, where it’s all happening.
This book contains stories about many different types of journey. We hope you will enjoy travelling into it and finding a world that suits you
Co-phasing the Large Binocular Telescope: status and performance of LBTI/PHASECam
The Large Binocular Telescope Interferometer is a NASA-funded nulling and
imaging instrument designed to coherently combine the two 8.4-m primary mirrors
of the LBT for high-sensitivity, high-contrast, and high-resolution infrared
imaging (1.5-13 um). PHASECam is LBTI's near-infrared camera used to measure
tip-tilt and phase variations between the two AO-corrected apertures and
provide high-angular resolution observations. We report on the status of the
system and describe its on-sky performance measured during the first semester
of 2014. With a spatial resolution equivalent to that of a 22.8-meter telescope
and the light-gathering power of single 11.8-meter mirror, the co-phased LBT
can be considered to be a forerunner of the next-generation extremely large
telescopes (ELT).Comment: 8 pages, 5 figures, SPIE Conference proceeding
An agent-based approach for the dynamic and decentralized service reconfiguration in collaborative production scenarios
Future industrial systems endorse the implementation of innovative paradigms addressing the continuous flexibility, reconfiguration, and evolution to face the volatility of dynamic markets demanding complex and customized products. Smart manufacturing relies on the capability to adapt and evolve to face changes, particularly by identifying, on-the-fly, opportunities to reconfigure its behavior and functionalities and offer new and more adapted services. This paper introduces an agent-based approach for service reconfiguration that allows the identification of the opportunities for reconfiguration in a pro-active and dynamic manner, and the implementation on-the-fly of the best strategies for the service reconfiguration that will lead to a better production efficiency. The developed prototype for a flexible manufacturing system case study allowed to verify the feasibility of greedy local service reconfiguration for competitive and collaborative industrial automation situations.info:eu-repo/semantics/publishedVersio
SDWFS-MT-1: A Self-Obscured Luminous Supernova at z~0.2
We report the discovery of a six-month-long mid-infrared transient,
SDWFS-MT-1 (aka SN 2007va), in the Spitzer Deep, Wide-Field Survey of the NOAO
Deep Wide-Field Survey Bootes field. The transient, located in a z=0.19 low
luminosity (M_[4.5]~-18.6 mag, L/L_MilkyWay~0.01) metal-poor (12+log(O/H)~7.8)
irregular galaxy, peaked at a mid-infrared absolute magnitude of M_[4.5]~-24.2
in the 4.5 micron Spitzer/IRAC band and emitted a total energy of at least
10^51 ergs. The optical emission was likely fainter than the mid-infrared,
although our constraints on the optical emission are poor because the transient
peaked when the source was "behind" the Sun. The Spitzer data are consistent
with emission by a modified black body with a temperature of ~1350 K. We rule
out a number of scenarios for the origin of the transient such as a Galactic
star, AGN activity, GRB, tidal disruption of a star by a black hole and
gravitational lensing. The most plausible scenario is a supernova exploding
inside a massive, optically thick circumstellar medium, composed of multiple
shells of previously ejected material. If the proposed scenario is correct,
then a significant fraction (~10%) of the most luminous supernova may be
self-enshrouded by dust not only before but also after the supernova occurs.
The spectral energy distribution of the progenitor of such a supernova would be
a slightly cooler version of eta Carina, peaking at 20-30 microns.Comment: 26 pages, 5 figures, 1 table, accepted for publication in Ap
- …