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The Near-Earth Object (NEO) Surveyor mission is a NASA Observatory designed to discover and characterize asteroids and comets. The mission’s primary objective is to find the majority of objects large enough to cause severe regional impact damage (>140 m in effective spherical diameter) within its 5 yr baseline survey. Operating at the Sun–Earth L1 Lagrange point, the mission will survey to within 45° of the Sun in an effort to find objects in the most Earth-like orbits. The survey cadence is optimized to provide observational arcs long enough to distinguish near-Earth objects from more distant small bodies that cannot pose an impact hazard reliably. Over the course of its survey, NEO Surveyor will discover ∼200,000–300,000 new NEOs down to sizes as small as ∼10 m and thousands of comets, significantly improving our understanding of the probability of an Earth impact over the next century.

The Spitzer Survey of Stellar Structure in Galaxies ([inline image]) is an Exploration Science Legacy Program approved for the Spitzer post-cryogenic mission. It is a volume-, magnitude-, and size-limited (d < 40 Mpc,

TheSpitzerSurvey of Stellar Structure in Galaxies ( S 4 G ) is an Exploration Science Legacy Program approved for theSpitzerpost–cryogenic mission. It is a volume-, magnitude-, and size-limited ( d < 40 Mpc d < 40     Mpc ,|b| > 30° | b | > 30 ° , m Bcorr < 15.5 m B corr < 15.5 , and D 25 > 1′ D 25 > 1 ′ ) survey of 2331 galaxies using the Infrared Array Camera (IRAC) at 3.6 and 4.5 μm. Each galaxy is observed for 240 s and mapped to≥1.5 × D 25 ≥ 1.5 × D 25 . The final mosaicked images have a typical 1σ rms noise level of 0.0072 and0.0093 MJy sr-1 0.0093     MJy   sr - 1 at 3.6 and 4.5 μm, respectively. Our azimuthally averaged surface brightness profile typically traces isophotes atμ3.6μm(AB)(1σ) ∼ 27 mag arcsec-2 μ 3.6 μ m ( AB ) ( 1 σ ) ∼ 27     mag   arcsec - 2 , equivalent to a stellar mass surface density of∼1 M ⊙pc-2 ∼ 1     M ⊙ pc - 2 . S 4 G thus provides an unprecedented data set for the study of the distribution of mass and stellar structures in the local universe. This large, unbiased, and extremely deep sample of all Hubble types from dwarfs to spirals to ellipticals will allow for detailed structural studies, not only as a function of stellar mass, but also as a function of the local environment. The data from this survey will serve as a vital testbed for cosmological simulations predicting the stellar mass properties of present-day galaxies. This article introduces the survey and describes the sample selection, the significance of the 3.6 and 4.5 μm bands for this study, and the data collection and survey strategies. We describe the S 4 G data analysis pipeline and present measurements for a first set of galaxies, observed in both the cryogenic and warm mission phases ofSpitzer. For every galaxy we tabulate the galaxy diameter, position angle, axial ratio, inclination atμ3.6μm(AB) = 25.5 μ 3.6 μ m ( AB ) = 25.5 , and26.5 mag arcsec-2 26.5     mag   arcsec - 2 (equivalent to≈μB(AB) = 27.2 ≈ μ B ( AB ) = 27.2 and28.2 mag arcsec-2 28.2     mag   arcsec - 2 , respectively). These measurements will form the initial S 4 G catalog of galaxy properties. We also measure the total magnitude and the azimuthally averaged radial profiles of ellipticity, position angle, surface brightness, and color. Finally, using the galaxy-fitting code GALFIT, we deconstruct each galaxy into its main constituent stellar components: the bulge/spheroid, disk, bar, and nuclear point source, where necessary. Together, these data products will provide a comprehensive and definitive catalog of stellar structures, mass, and properties of galaxies in the nearby universe and will enable a variety of scientific investigations, some of which are highlighted in this introductory S 4 G survey paper.

The Near-Earth Object (NEO) Surveyor mission is a NASA observatory designed to discover and characterize near-Earth asteroids and comets. The mission's primary objective is to find the majority of objects large enough to cause severe regional impact damage (\\(>\\)140 m in effective spherical diameter) within its five-year baseline survey. Operating at the Sun-Earth L1 Lagrange point, the mission will survey to within 45 degrees of the Sun in an effort to find the objects in the most Earth-like orbits. The survey cadence is optimized to provide observational arcs long enough to reliably distinguish near-Earth objects from more distant small bodies that cannot pose an impact hazard. Over the course of its survey, NEO Surveyor will discover \\(\\)200,000 - 300,000 new NEOs down to sizes as small as \\(\\)10 m and thousands of comets, significantly improving our understanding of the probability of an Earth impact over the next century.

We describe a Herschel Space Observatory 194-671 micron spectroscopic survey of a sample of 121 local luminous infrared galaxies and report the fluxes of the CO \\(J\\) to \\(J\\)-1 rotational transitions for \\(4 J 13\\), the [NII] 205 um line, the [CI] lines at 609 and 370 um, as well as additional and usually fainter lines. The CO spectral line energy distributions (SLEDs) presented here are consistent with our earlier work, which was based on a smaller sample, that calls for two distinct molecular gas components in general: (i) a cold component, which emits CO lines primarily at \\(J 4\\) and likely represents the same gas phase traced by CO (1-0), and (ii) a warm component, which dominates over the mid-\\(J\\) regime (\\(4 < J < 10\\)) and is intimately related to current star formation. We present evidence that the CO line emission associated with an active galactic nucleus is significant only at \\(J > 10\\). The flux ratios of the two [CI] lines imply modest excitation temperatures of 15 to 30 K; the [CI] 370 um line scales more linearly in flux with CO (4-3) than with CO (7-6). These findings suggest that the [CI] emission is predominately associated with the gas component defined in (i) above. Our analysis of the stacked spectra in different far-infrared (FIR) color bins reveals an evolution of the SLED of the rotational transitions of water vapor as a function of the FIR color in a direction consistent with infrared photon pumping.

The possible evolutionary connection between ultraluminous infrared galaxies (ULIGs:$L\\sb{\\rm bol} > 10\\sp{12}$L $\\sb{\\odot})$and optically selected quasi-stellar objects (QSOs) was investigated. Three complete samples were examined: (1) \"warm\" ULIGs with mid-infrared colors characteristic of active galactic nuclei$\\rm (f\\sb{25\\mu m}/f\\sb{60\\mu m}\\ >0.2)$ , which appear to represent a critical transition phase between the second and third samples (2) \"cool\" ULIGs$\\rm (f\\sb{25\\mu m}/f\\sb{60\\mu m} <0.2)$which appear to be the progenitors of warm ULIGs and which have many active star-formation characteristics, and (3) far-IR excess QSOs which have infrared to blue luminosity ratios at least as great as those of the \"warm\" ULIGs. High spatial resolution observations (FWHM $\\approx$0.3-0.8 $\\sp{\\prime\\prime})$were made at wavelengths ranging from the near-ultraviolet ( $\\lambda$= 3200A) to near-infrared ( $\\lambda$= 2.1 $\\mu$ m). The following are the major findings: (1) all ULIGs have small scale structure in their central few kiloparsecs, (2) this structure is consistent in most cases with knots of powerful star formation which are insignificant in terms of their contribution to the high bolometric luminosity of the systems, (3) some of these knots have colors and luminosities consistent with QSO nuclei seen through patchy emission and extinction, (4) both ULIGs and QSOs have similar total mass host galaxies, (5) mergers are implicated in at least 22% of far-IR excess QSOs; 50% also have nuclear disturbances, and (6) there is evidence that the fraction of active nuclei detectable in the optical and near-infrared increases with the estimated dynamical age of the systems. These results are consistent with the idea that at least some ( $\\approx$ 30%) QSOs like those examined here evolve via mergers from progenitors similar to the ULIGs, and that the ultimate fate of most ULIGs is to form systems similar in properties to optical QSOs. Implications for the evolution of active nuclei and clustered star formation in merging far-infrared active galaxies are discussed.

PSR J2129-0429 is a \"redback\" eclipsing millisecond pulsar binary with an unusually long 15.2 hour orbit. It was discovered by the Green Bank Telescope in a targeted search of unidentified Fermi gamma-ray sources. The pulsar companion is optically bright (mean \\(m_R = 16.6\\) mag), allowing us to construct the longest baseline photometric dataset available for such a system. We present ten years of archival and new photometry of the companion from LINEAR, CRTS, PTF, the Palomar 60-inch, and LCOGT. Radial velocity spectroscopy using the Double-Beam Spectrograph on the Palomar 200-inch indicates that the pulsar is massive: \\(1.740.18 M_\\). The G-type pulsar companion has mass \\(0.440.04 M_\\), one of the heaviest known redback companions. It is currently 95\\% Roche-lobe filling and only mildly irradiated by the pulsar. We identify a clear 13.1 mmag yr\\(^-1\\) secular decline in the mean magnitude of the companion as well as smaller-scale variations in the optical lightcurve shape. This behavior may indicate that the companion is cooling. Binary evolution calculations indicate that PSR J2129-0429 has an orbital period almost exactly at the bifurcation period between systems that converge into tighter orbits as black widows and redbacks and those that diverge into wider pulsar--white dwarf binaries. Its eventual fate may depend on whether it undergoes future episodes of mass transfer and increased irradiation.

We present new Karl G. Jansky Very Large Array radio continuum images of the nuclei of Arp 220, the nearest ultra-luminous infrared galaxy. These images have both the angular resolution to study detailed morphologies of the two nuclei that power the system and sensitivity to a wide range of spatial scales. At 33 GHz, and with a resolution of 0\".081 x 0\".063 (29.9 x 23.3 pc), we resolve the emission surrounding both nuclei and conclude that is mostly synchrotron in nature. The spatial distributions of radio emission in both nuclei are well described by exponential profiles. These have deconvolved half-light radii of 51 and 35 pc for the eastern and western nuclei, and they match the number density profile of radio supernovae observed with very long baseline interferometry. This similarity might be due to the fast cooling of cosmic rays electrons caused by the presence of a strong (~ mG) magnetic field in this system. We estimate high luminosity surface densities of \\(_IR 4.2^+1.6_-0.7 10^13\\) (east) and \\( 9.7^+3.7_-2.4 10^13~(west)~L_~kpc^-2\\), and star formation rate surface densities of \\(_SFR 10^3.70.1\\) (east) and \\( 10^4.10.1~(west)~M_~yr^-1~kpc^-2\\). These values, especially for the western nucleus are, to our knowledge, the highest luminosity and star formation rate surface densities measured for any star-forming system. Despite these high values, the nuclei lie below the dusty Eddington limit in which radiation pressure is balanced only by self-gravity. The small measured sizes also imply that the nuclei of Arp 220 are only transparent in the frequency range ~ 5 to 350 GHz. Our results offer no clear evidence that an active galactic nucleus dominates the emission from either nucleus at 33 GHz.

We report positions, velocities and metallicities of 50 ab-type RR Lyrae (RRab) stars observed in the vicinity of the Orphan stellar stream. Using about 30 RRab stars classified as being likely members of the Orphan stream, we study the metallicity and the spatial extent of the stream. We find that RRab stars in the Orphan stream have a wide range of metallicities, from -1.5 dex to -2.7 dex. The average metallicity of the stream is -2.1 dex, identical to the value obtained by Newberg et al. (2010) using blue horizontal branch stars. We find that the most distant parts of the stream (40-50 kpc from the Sun) are about 0.3 dex more metal-poor than the closer parts (within ~30 kpc), suggesting a possible metallicity gradient along the stream's length. We have extended the previous studies and have mapped the stream up to 55 kpc from the Sun. Even after a careful search, we did not identify any more distant RRab stars that could plausibly be members of the Orphan stream. If confirmed with other tracers, this result would indicate a detection of the end of the leading arm of the stream. We have compared the distances of Orphan stream RRab stars with the best-fit orbits obtained by Newberg et al. (2010). We find that model 6 of Newberg et al. (2010) cannot explain the distances of the most remote Orphan stream RRab stars, and conclude that the best fit to distances of Orphan stream RRab stars and to the local circular velocity is provided by potentials where the total mass of the Galaxy within 60 kpc is M_60~2.7x10^11 Msun, or about 60% of the mass found by previous studies. More extensive modelling that would consider non-spherical potentials and the possibility of misalignment between the stream and the orbit, is highly encouraged.

The dominant non-instrumental background source for space-based infrared observatories is the zo- diacal light. We present Spitzer Infrared Array Camera (IRAC) measurements of the zodiacal light at 3.6, 4.5, 5.8, and 8.0 m, taken as part of the instrument calibrations. We measure the changing surface brightness levels in approximately weekly IRAC observations near the north ecliptic pole (NEP) over the period of roughly 8.5 years. This long time baseline is crucial for measuring the annual sinusoidal variation in the signal levels due to the tilt of the dust disk with respect to the ecliptic, which is the true signal of the zodiacal light. This is compared to both Cosmic Background Explorer Diffuse Infrared Background Experiment (COBE DIRBE) data and a zodiacal light model based thereon. Our data show a few percent discrepancy from the Kelsall et al. (1998) model including a potential warping of the interplanetary dust disk and a previously detected overdensity in the dust cloud directly behind the Earth in its orbit. Accurate knowledge of the zodiacal light is important for both extragalactic and Galactic astronomy including measurements of the cosmic infrared background, absolute measures of extended sources, and comparison to extrasolar interplanetary dust models. IRAC data can be used to further inform and test future zodiacal light models.