We used Optical Gravitational Lensing Experiment (OGLE-IV) deep (stacked) images (V less than or similar to 23 mag, I less than or similar to 23 mag at 3 sigma) of the Magellanic System, encompassing an area of similar to 670 deg(2), to perform a search for high-z quasar candidates. We combined the optical OGLE data with the mid-IR Wide-field Infrared Survey Explorer 3.4/4.6/12 mu m data, and devised a multicolor selection procedure. We identified 33 promising candidates and then spectroscopically observed the two most variable sources. We report the discovery of two high-z quasars, OGLE.J015531-752807 at a redshift z = 5.09 and OGLE.J005907-645016.at a redshift of z = 4.98. The variability amplitude of both quasars at the rest-frame wavelength similar to 1300 angstrom is much larger (similar to 0.4 mag) than other quasars (similar to 0.15 mag) at the same rest-frame wavelength but lower redshifts (2 < z < 5). A larger sample of such sources with at least decade-long light curves would be necessary to determine whether increased variability is typical in the population of high-z quasars, or whether we are finding extreme outliers. The Large Synoptic Survey Telescope will provide such light curves for sources 3-4 mag fainter than OGLE.

The binary fraction of unevolved massive stars is thought to be 70%-100% but there are few observational constraints on the binary fraction of the evolved version of a subset of these stars, the red supergiants (RSGs). Here we identify a complete sample of RSGs in the Large Magellanic Cloud (LMC) using new spectroscopic observations and archival UV, IR, and broadband optical photometry. We find 4090 RSGs with log L/L-circle dot > 3.5, with 1820 of them having log L/L-circle dot >, which we believe is our completeness limit. We additionally spectroscopically confirmed 38 new RSG + B-star binaries in the LMC, bringing the total known up to 55. We then estimated the binary fraction using a k-nearest neighbors algorithm that classifies stars as single or binary based on photometry with a spectroscopic sample as a training set. We take into account observational biases such as line-of-sight stars and binaries in eclipse while also calculating model-dependent corrections for RSGs with companions that our observations were not designed to detect. Based on our data, we find an initial result of 13.5(-6.67)(+7.56)% for RSGs with O- or B-type companions. Using the Binary Population and Spectral Synthesis models to correct for unobserved systems, this corresponds to a total RSG binary fraction of 19.5(-6.7)(+7.6) %. This number is in broad agreement with what we would expect given an initial OB binary distribution of 70%, a predicted merger fraction of 20%-30%, and a binary interaction fraction of 40%-50%.

We present the results from a high-cadence, multiwavelength observation campaign of AT 2016jbu (aka Gaia16cfr), an interacting transient. This data set complements the current literature by adding higher cadence as well as extended coverage of the light-curve evolution and late-time spectroscopic evolution. Photometric coverage reveals that AT 2016jbu underwent significant photometric variability followed by two luminous events, the latter of which reached an absolute magnitude of M-V similar to-18.5 mag. This is similar to the transient SN 2009ip whose nature is still debated. Spectra are dominated by narrow emission lines and show a blue continuum during the peak of the second event. AT 2016jbu shows signatures of a complex, non-homogeneous circumstellar material (CSM). We see slowly evolving asymmetric hydrogen line profiles, with velocities of 500 km s(-)(1) seen in narrow emission features from a slow-moving CSM, and up to 10 000 km s(-1) seen in broad absorption from some high-velocity material. Late-time spectra (similar to+1 yr) show a lack of forbidden emission lines expected from a core-collapse supernova and are dominated by strong emission from H, He I, and Ca II. Strong asymmetric emission features, a bumpy light curve, and continually evolving spectra suggest an inhibit nebular phase. We compare the evolution of H alpha among SN 2009ip-like transients and find possible evidence for orientation angle effects. The light-curve evolution of AT 2016jbu suggests similar, but not identical, circumstellar environments to other SN 2009ip-like transients.

We present the bolometric light curve, identification and analysis of the progenitor candidate, and preliminary modelling of AT 2016jbu (Gaia16cfr). We find a progenitor consistent with a similar to 22-25 M-circle dot yellow hypergiant surrounded by a dusty circumstellar shell, in agreement with what has been previously reported. We see evidence for significant photometric variability in the progenitor, as well as strong H alpha emission consistent with pre-existing circumstellar material. The age of the environment, as well as the resolved stellar population surrounding AT 2016jbu, supports a progenitor age of >10 Myr, consistent with a progenitor mass of similar to 22 M-circle dot. A joint analysis of the velocity evolution of AT 2016jbu and the photospheric radius inferred from the bolometric light curve shows the transient is consistent with two successive outbursts/explosions. The first outburst ejected material with velocity similar to 650 km s(-1), while the second, more energetic event ejected material at similar to 4500 km s(-1). Whether the latter is the core collapse of the progenitor remains uncertain. We place a limit on the ejected Ni-56 mass of <0.016 M-circle dot. Using the Binary Population And Spectral Synthesis (BPASS) code, we explore a wide range of possible progenitor systems and find that the majority of these are in binaries, some of which are undergoing mass transfer or common-envelope evolution immediately prior to explosion. Finally, we use the SuperNova Explosion Code (SNEC) to demonstrate that the low-energy explosions within some of these binary systems, together with sufficient circumstellar material, can reproduce the overall morphology of the light curve of AT 2016jbu.

The La; Campanas Infrared Survey is a photometric redshift survey designed to study the evolution and clustering of evolved galaxies over the redshift range 1 < z < 2. The survey is motivated by the construction of a unique, wide-field infrared camera for the Las Campanas 2.5m telescope. The primary goals are to obtain infrared imaging of a square degree to K-s = 21.1 and J = 22.7 along with deep optical imaging in VRIz' We discuss the scientific and technical goals of the survey, and we present the first survey images obtained in April 1999.

SN 1999aw was discovered during the first campaign of the Nearby Galaxies Supernova Search project. This luminous, slow-declining [Deltam(15)(B) = 0.81 +/- 0.03] Type Ia supernova was noteworthy in at least two respects. First, it occurred in an extremely low luminosity host galaxy that was not visible in the template images nor in initial subsequent deep imaging. Second, the photometric and spectral properties of this supernova indicate that it very likely was similar to the subclass of Type Ia supernovae whose prototype is SN 1999aa. This paper presents the BVRI and J(s)HK(s) light curves of SN 1999aw ( through similar to100 days past maximum light), as well as several epochs of optical spectra. From these data, we calculate the bolometric light curve and give estimates of the luminosity at maximum light and the initial Ni-56 mass. In addition, we present deep BVI images obtained recently with the Baade 6.5 m telescope at Las Campanas Observatory that reveal the remarkably low-luminosity host galaxy.

We describe a compact cluster or group of massive red galaxies at discovered in one of the Gemini z = 1.5 Deep Deep Survey (GDDS) fields. Deep H- band imaging from the Hubble Space Telescope (HST) reveals a high density of red galaxies associated with a galaxy with a spectroscopic redshift of 1.51. These galaxies have spectral energy distributions (SEDs) that peak between 3.6 and 4.5 mu m, and fits to 12- band photometry reveal 12 or more galaxies with spectral shapes consistent with. Most are within similar to 170 comoving kpc of the z = 1.5 GDDS galaxy, and the enclosed stellar mass is >16 x 10(11) M circle dot. The colors of the most massive galaxies are close to those expected from passive evolution of simple stellar populations (SSPs) formed at much higher redshifts. We suggest that several of these galaxies will merge to form a single, very massive galaxy by the present day. This system may represent an example of a short- lived dense group or cluster core typical of the progenitors of massive clusters in the present day and suggests that the red sequence was in place in overdense regions at early times.

Aims. We present new near-infrared (NIR) light-curve templates for fundamental (FU, J, H, K-S) and first overtone (FO, J) classical Cepheids. The new templates together with period-luminosity and period-Wesenheit (PW) relations provide Cepheid distances from single-epoch observations with a precision only limited by the intrinsic accuracy of the method adopted.

We present ultraviolet (UV) spectroscopy and photometry of four Type Ia supernovae (SNe 2004dt, 2004ef, 2005M, and 2005cf) obtained with the UV prism of the Advanced Camera for Surveys on the Hubble Space Telescope. This data set provides unique spectral time series down to 2000 angstrom. Significant diversity is seen in the near-maximum-light spectra (similar to 2000-3500 angstrom) for this small sample. The corresponding photometric data, together with archival data from Swift Ultraviolet/Optical Telescope observations, provide further evidence of increased dispersion in the UV emission with respect to the optical. The peak luminositiesmeasured in the uvw1/F250W filter are found to correlate with the B-band light-curve shape parameter Delta m(15)(B), but with much larger scatter relative to the correlation in the broadband B band (e.g., similar to 0.4 mag versus similar to 0.2 mag for those with 0.8 mag < Delta m(15)(B) < 1.7 mag). SN 2004dt is found as an outlier of this correlation (at > 3 sigma), being brighter than normal SNe Ia such as SN 2005cf by similar to 0.9 mag and similar to 2.0 mag in the uvw1/F250W and uvm2/F220W filters, respectively. We show that different progenitor metallicity or line-expansion velocities alone cannot explain such a large discrepancy. Viewing-angle effects, such as due to an asymmetric explosion, may have a significant influence on the flux emitted in the UV region. Detailed modeling is needed to disentangle and quantify the above effects.