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UnISIS (University of Illinois Seeing Improvement System) is a versatile adaptive optics system mounted on a large optics bench at the coudé focus of the Mount Wilson 2.5-m telescope. It was designed to have both laser guide star (LGS) and natural guide star (NGS) adaptive optics capabilities. The LGS side of the system relies on a pulsed UV laser with raw power of 30 W capable of creating an artificial laser star via Rayleigh scattering 18 km above the telescope. The LGS system can work at temporal response rates as high as 333 Hz—limited by the UV laser pulse rate—and the NGS system can work at rates up to 1.4 kHz. Each side of the system has its own high-speed wavefront sensor that runs separately, but in the LGS mode the NGS wavefront sensor is converted into a natural star tip-tilt sensor. The deformable mirror is conjugate to the telescope’s primary mirror and has one of the most densely packed sets of actuators of any adaptive optics system currently in operation. This paper provides details of the UnISIS design and describes key updates we have made to the system. We show NGS AO-corrected images from the sky from the 900 nm z z -band through the 2.12 μmK s K s band. The highest NGS Strehl achieved to date is 0.67 at K s K s band.

Multi-messenger astrophysics is a fast-growing, interdisciplinary field that combines data, which vary in volume and speed of data processing, from many different instruments that probe the Universe using different cosmic messengers: electromagnetic waves, cosmic rays, gravitational waves and neutrinos. In this Expert Recommendation, we review the key challenges of real-time observations of gravitational wave sources and their electromagnetic and astroparticle counterparts, and make a number of recommendations to maximize their potential for scientific discovery. These recommendations refer to the design of scalable and computationally efficient machine learning algorithms; the cyber-infrastructure to numerically simulate astrophysical sources, and to process and interpret multi-messenger astrophysics data; the management of gravitational wave detections to trigger real-time alerts for electromagnetic and astroparticle follow-ups; a vision to harness future developments of machine learning and cyber-infrastructure resources to cope with the big-data requirements; and the need to build a community of experts to realize the goals of multi-messenger astrophysics.A group of experts suggests ways in which deep learning can be used to enhance the potential for discovery in multi-messenger astrophysics.

Detailed 4.8 and 8.64 GHz radio images of the entire Large and Small Magellanic Clouds with half-power beamwidths of 35″ at 4.8 GHz and 22″ at 8.64 GHz have been obtained using the Australia Telescope Compact Array. Full polarimetric observations were made. Several thousand mosaic positions were used to cover an area of 6° on a side for the LMC and 4.5° for the SMC. These images have sufficient spatial resolution (~ 8 and 5 pc, respectively) and sensitivity (3σ of 1.5 mJy beam−1) to identify most of the individual supernova remnants and H ii regions and also, in combination with available data from the Parkes 64-m telescope, the structure of the smooth emission in these galaxies. We have recently revised the early data analysis (Dickel et al. 2005) by increasing the CLEAN cutoff limit to recover more intermediate-spacing data and thus present more accurate brightnesses for extended sources. In addition, limited data using the sixth antenna at 4.5 – 6 km baselines are available to distinguish bright point sources (< 3″ and 2″, respectively) and to help estimate sizes of individual sources smaller than the resolution of the full survey. The resulting database will be valuable for statistical studies and comparisons with X-ray, optical, and infrared surveys of the LMC with similar resolution.

We survey HII free-free emission around ∼60 spectroscopically confirmed young stellar objects (YSOs) in the Large Magellanic Cloud using the Australia Telescope Compact Array (ATCA) at 3.3 and 5.5 cm. From each YSOs' infrared spectrum, we: a) quantify how embedded/evolved the YSO is through principle component analysis (PCA) of the silicate absorption (Seale et al. 2009); and b) estimate the mass from SED models (Robitaille et al. 2007). We have four main results: (1) Based on mass estimates from SED models and ATCA detection limits, we find that most massive YSOs are in HII regions regardless of age; (2) Older massive YSOs (as indicated by silicate PCA index) are much more likely to be resolved than younger YSOs, indicating evolving HII regions; (3) Resolved (typically older) sources usually have lower densities. Thus, in our survey we see a transition from ultra-compact HII to HII regions; and (4) We find that accretion about the massive YSO is likely non-spherical, resulting in HII regions in the shape of prolate spheroids.

We present XMM-Newton and Chandra observations of the born-again planetary nebula A 30. These X-ray observations reveal a bright unresolved source at the position of the central star whose X-ray luminosity exceeds by far the model expectations for photospheric emission and for shocks within the stellar wind. We suggest that a “born-again hot bubble” may be responsible for this X-ray emission. Diffuse X-ray emission associated with the petal-like features and one of the H-poor knots seen in the optical is also found. The weakened emission of carbon lines in the spectrum of the diffuse emission can be interpreted as the dilution of stellar wind by mass-loading or as the detection of material ejected during a very late thermal pulse.

Evidence for triggered star formation is difficult to establish because energy feedback from massive stars tend to erase the interstellar conditions that led to the star formation. Young stellar objects (YSOs) mark sites of current star formation whose ambient conditions have not been significantly altered. Spitzer observations of the Large Magellanic Cloud (LMC) effectively reveal massive YSOs. The inventory of massive YSOs, in conjunction with surveys of interstellar medium, allows us to examine the conditions for star formation: spontaneous or triggered. We examine the relationship between star formation and gravitational instability on a global scale, and we present evidence of triggered star formation on local scales in the LMC.

Diffuse X-ray emission from hot gas in planetary nebulae (PNe) was hinted by ROSAT and ASCA, but only the improved sensitivity and spatial resolution of XMM-Newton and Chandra have allowed detailed studies of the hot gas in PNe. These studies are helping us to better assess the effects of fast stellar winds and collimated outflows in the shaping and evolution of individual PNe, but a comprehensive picture is lacking, because the X-ray analysis of different PNe is not homogeneous and, therefore, cannot be intercompared. Furthermore, a significant number of X-ray observations of PNe that did not detect X-ray emission have not been reported. We have undertaken a systematic study of all XMM-Newton and Chandra observations of PNe benefiting from a homogeneous analysis using the most up-to-date versions of SAS and CIAO, respectively, and the recently released calibration files with greater accuracy for energies below 1.0 keV. We present reprocessed event files, derived data products (X-ray images and spectra), supporting observations at other wavelengths, and analysis results in a database, the XPN Database, that can be accessed at http://www.iaa.csic.es/xpn

The formation and evolution of planetary nebulae (PNe) is largely attributed to the interaction of the fast stellar wind with the wind of the Asymptotic Giant Branch (AGB), and to the dynamical effects of the photo-ionization of the nebular material. The physical structure of a PN can be used to assess the relative importance of fast stellar winds and photo-ionization in its shaping and evolution, but there is little information on the hot gas content of PNe. Using our recent XMM-Newton observations of NGC 3242, we have made a comprehensive analysis of the physical structure of this nebula, combining the physical conditions of the shocked fast stellar wind in its interior and the spatio-dynamical structure and physical conditions of the photo-ionized material.

We present an atlas of stellar sight line data from the Far Ultraviolet Spectroscopic Explorer (FUSE) satellite for 287 stars in the Magellanic Clouds, obtained from eight years of satellite operations. The intent of our project is to make this rich ensemble data set accessible to a broad community of researchers in a standardized format that will enable easy identification of subsets of these data that are appropriate for pursuing specific science programs. We present the data in a standardized manner, showing key interstellar lines on a velocity scale, optical (MCELS) and infrared (Spitzer) sight line context images, and overview plots of the spectral region containing the O VI λλ1032, 1038 doublet, and the entire 905–1187 Å spectral range observed withFUSE. Objects with multiple observations have had their data summed to directly provide the highest signal-to-noise ratio available. These data are accessible online as a High Level Science Product through the Multimission Archive at Space Telescope (MAST). In this article, we describe the data sets and processing, the atlas materials, and the MAST interface in detail, and also provide examples of how to use these materials.