Comet 85P/Boethin was selected as the original comet target for the Deep Impact extended mission, EPOXI. Because this comet had been only observed at two apparitions in 1975 and 1986 and consequently had a large ephemeris error, an early intense recovery effort similar to that of 1P/Halley was undertaken beginning in 2005 using the ESO Very Large Telescopes (VLTs) in a distant comet program. These were challenging observations because of the low galactic latitude, and an error ellipse (the line of variations) that was larger than the CCD FOV, and the comet was not seen. Dedicated recovery observing time was awarded on the Subaru telescope in April and May 2006, and June 2007, in addition to time on the VLT and Canada France Hawaii telescopes during July August 2007 with wide field mosaics and mosaicing techniques. The limiting V magnitudes from these observing runs ranged between 25.7 and 27.3 and again the comet was not seen in the individual nights. A new image processing technique was developed to stack images over extended runs and runs after distorting them to account for dilations and rotations in the line of variations using modifications of the world coordinate system. A candidate at V 27.3 was found in the CFHT data along the LOV, 2.5' west of the nominal ephemeris position. The EPOXI mission was unwilling to re-target the spacecraft without a confirmation. Additional time was secured using the Spitzer Space Telescope, the Gemini South 8-m telescope, the Clay and Baade (Magellan 6.5 m), CTIO 4 m, and SOAR 4 m telescopes during 2007 September and October A composite image made by stacking the new data showed no plausible candidate nucleus to a limiting magnitude of V = 28.5, corresponding to a nucleus radius between 0.1 and 0.2 km (assuming an albedo of 0.04). The comet was declared lost, presumably having disintegrated. Searches in the WISE data set revealed no debris trail, but no constraints on the possible time of disruption can be made. NASA approved the trajectory correction maneuver to go to Comet 103P/Hartley 2 on 2007 November 1. Many observers searched for the comet as it came to its December 2008 perihelion, but no trace of the nucleus was found.

The Japanese Space Agency's Hayabusa II mission is scheduled to rendezvous with and return a sample from the near-Earth Asteroid (162173) 1999 JU3. Previous visible-wavelength spectra of this object show significant variability across multiple epochs which has been attributed to a compositionally heterogeneous surface. We present new visible and near-infrared spectra to demonstrate that thermally altered carbonaceous chondrites are plausible compositional analogs, however this is a tentative association due to a lack of prominent absorption features in our data. We have also conducted a series of high signal-to-noise visible-wavelength observations to investigate the reported surface heterogeneity. Our time series of visible spectra do not show variability at a precision level of a few percent. This result suggests two most likely possibilities. One, that the surface of 1999 JU3 is homogenous and that unaccounted for systematic effects are causing spectral variation across epochs. Or two, that the surface of 1999 JU3 is regionally heterogenous, in which case existing shape models suggest that any heterogeneity must be limited to terrains smaller than approximately 5% of the total surface area. These new observations represent the last opportunity before both the launch and return of the Hayabusa II spacecraft to perform ground-based characterization of this asteroid. Ultimately, these predictions for composition and surface properties will be tested upon completion of the mission. (C) 2013 Elsevier Inc. All rights reserved.

We investigated the magnitude-phase relation of (162173) 1999 JU3, a target asteroid for the JAXA Hayabusa 2 sample return mission. We initially employed the International Astronomical Union's H-G formalism but found that it fits less well using a single set of parameters. To improve the inadequate fit, we employed two photometric functions: the Shevchenko and Hapke functions. With the Shevchenko function, we found that the magnitude-phase relation exhibits linear behavior in a wide phase angle range (alpha = 5 degrees-75 degrees) and shows weak nonlinear opposition brightening at alpha < 5 degrees, providing a more reliable absolute magnitude of H-V = 19.25 +/- 0.03. The phase slope (0.039 +/- 0.001 mag deg(-1)) and opposition effect amplitude (parameterized by the ratio of intensity at alpha = 0 degrees.3 to that at alpha = 5 degrees, I(0 degrees.3)/I(5 degrees) = 1.31 +/- 0.05) are consistent with those of typical C-type asteroids. We also attempted to determine the parameters for the Hapke model, which are applicable for constructing the surface reflectance map with the Hayabusa 2 onboard cameras. Although we could not constrain the full set of Hapke parameters, we obtained possible values, w = 0.041, g = -0.38, B-0 = 1.43, and h = 0.050, assuming a surface roughness parameter <(theta)over bar> = 20 degrees. By combining our photometric study with a thermal model of the asteroid, we obtained a geometric albedo of p(v) = 0.047 +/- 0.003, phase integral q = 0.32 +/- 0.03, and Bond albedo A(B) = 0.014 +/- 0.002, which are commensurate with the values for common C-type asteroids.

GJ. 1214b is the most studied sub-Neptune exoplanet to date. Recent measurements have shown its near-infrared transmission spectrum to be flat, pointing to a high-altitude opacity source in the exoplanet 's atmosphere, either equilibrium condensate clouds or photochemical hazes. Many photometric observations have been reported in the optical by different groups, though simultaneous measurements spanning the entire optical regime are lacking. We present an optical transmission spectrum (4500-9260 angstrom) of GJ. 1214b in 14 bins, measured with Magellan/IMACS repeatedly over three transits. We measure a mean planet-to-star radius ratio of Rp R-s = 0.1146. 2 x 10(-4) and mean uncertainty of sigma(R-p/R-s) = 8.7 x 10(-4) in the spectral bins. The optical transit depths are shallower on average than observed in the near-infrared. We present a model for jointly incorporating the effects of a composite photosphere and atmospheric transmission through the exoplanet's limb (the CPAT model), and use it to examine the cases of absorber and temperature heterogeneities in the stellar photosphere. We find the optical and near-infrared measurements are best explained by the combination of (1) photochemical haze in the exoplanetary atmosphere with a mode particle size r = 0.1 mu m and haze-forming efficiency f(haze) = 10% and (2) faculae in the unocculted stellar disk with a temperature contrast Delta T= 354(-46)(+46) K, assuming 3.2% surface coverage. The CPAT model can be used to assess potential contributions of heterogeneous stellar photospheres to observations of exoplanet transmission spectra, which will be important for searches for spectral features in the optical.

We present an analysis of the host-galaxy environment of Swope Supernova Survey 2017a (SSS17a), the discovery of an electromagnetic counterpart to a gravitational-wave source, GW170817. SSS17a occurred 1.9. kpc (in projection; 10 ''.2) from the nucleus of NGC. 4993, an S0 galaxy at a distance of 40. Mpc. We present a Hubble Space Telescope (HST) pre-trigger image of NGC. 4993, Magellan optical spectroscopy of the nucleus of NGC. 4993 and the location of SSS17a, and broadband UV-through-IR photometry of NGC. 4993. The spectrum and broadband spectral-energy distribution indicate that NGC. 4993 has a stellar mass of log(M/M-circle dot) 10.49(-0.20) (+0.08) and star formation rate of 0.003 M-circle dot yr(-1), and the progenitor system of SSS17a likely had an age of >2.8. Gyr. There is no counterpart at the position of SSS17a in the HST pre-trigger image, indicating that the progenitor system had an absolute magnitude M-V > -5.8 mag. We detect dust lanes extending out to almost the position of SSS17a and >100 likely globular clusters associated with NGC. 4993. The offset of SSS17a is similar to many short gamma-ray-burst offsets, and its progenitor system was likely bound to NGC. 4993. The environment of SSS17a is consistent with an old progenitor system such as a binary neutron star system.

Las Campanas Observatory (LCO) of the Carnegie Institution of Science has been operating in Chile for about 50 years, currently operating four main telescopes. Carnegie operates the two 6.5 meter Magellan telescopes on behalf of a partnership that includes a consortium of universities. The Magellan Telescopes were commissioned in 2000 and 2002 and offer the consortium users a suite of twelve instruments. In this paper we will first provide a brief description of the science, technical and administrative structure of the observatory. We will then present an updated review of the Magellan telescopes operations and maintenance. Details on status and performances of the instruments will be given. We will finally cover the operations of the duPont 2.5 meter and Swope 1 meter telescopes including the current and future collaboration with the two hemisphere surveys SDSS-IV and SDSS-V.

We report the discovery of HATS-70b, a transiting brown dwarf at the deuterium burning limit. HATS-70b has a mass of M p = 12.9(-1.6)(+1.8) M-Jup and a radius of R-p = 1.384(-0.074) (+ 0.079) R-Jup, residing in a close-in orbit with a period of 1.89 days. The host star is a /14 * = 1.78 +/- 0.12 M-circle dot A star rotating at v sin I-* = 40.61(-0.35)(+0.32) km s( -1) , enabling us to characterize the spectroscopic transit of the brown dwarf via Doppler tomography. We find that HATS-70b, like other massive planets and brown dwarfs previously sampled, orbits in a low projected-obliquity orbit with lambda = 8.9(-4.5)+(5.6)(degrees). The low obliquities of these systems is surprising given all brown dwarf and massive planets with obliquities measured orbit stars hotter than the Kraft break. This trend is tentatively inconsistent with dynamically chaotic migration for systems with massive companions, though the stronger tidal influence of these companions makes it difficult to draw conclusions on the primordial obliquity distribution of this population. We also introduce a modeling scheme for planets around rapidly rotating stars, accounting for the influence of gravity darkening on the derived stellar and planetary parameters.

We present an optical transmission spectrum of the atmosphere of WASP-4b obtained through observations of four transits with Magellan/IMACS, as part of the Arizona-CfA-Catolica-Carnegie Exoplanet Spectroscopy Survey (ACCESS). Using a Bayesian approach to atmospheric retrieval, we find no evidence for scattering or absorption features in our transit spectrum. Our models include a component to model the transit light source effect (spectral contamination from unocculted spots on the stellar photosphere), which we show can have a marked impact on the observed transmission spectrum for reasonable spot-covering fractions (<5%); this is the first such analysis for WASP-4b. We are also able to fit for the size and temperature contrast of spots observed during the second and third transits, finding evidence for both small, cool and large, warm spot-like features on the photosphere. Finally, we compare our results to those published by Huitson et al. using Gemini/GMOS and May et al. using IMACS, and we find that our data are in agreement.

We report the discovery of K2-287b, a Saturn mass planet orbiting a G-dwarf with a period of P approximate to 15 days. First uncovered as a candidate using K2 campaign 15 data, follow-up photometry and spectroscopy were used to determine a mass M-p = 0.317 +/- 0.026 M-J, radius R-p = 0.833 +/- 0.013 R-J, period P = 14.893291 +/- 0.000025 days, and eccentricity e = 0.476 +/- 0.026. The host star is a metal-rich V = 11.410 +/- 0.129 mag G-dwarf for which we estimate a mass M-* = 1.056(-0.021)(+0.022) M-circle dot, radius R-* = 1.070 +/- 0.010 R-circle dot, metallicity [Fe/H] = 0.20 +/- 0.05, and T-eff = 5673 +/- 75 K. This warm eccentric planet with a time-averaged equilibrium temperature of T-eq approximate to 800 K adds to the small sample of giant planets orbiting nearby stars whose structure is not expected to be affected by stellar irradiation. Follow-up studies on the K2-287 system could help constrain theories of planet migration in close-in orbits.

We present new eclipse observations for one of the hottest 'hot Jupiters', WASP-18b, for which previously published data from HST WFC3 and Spitzer have led to radically conflicting conclusions about the composition of this planet's atmosphere. We measure eclipse depths of 0.15 +/- 0.02 per cent at Ks and 0.07 +/- 0.01 per cent at i bands. Using the VSTAR line-by-line radiative transfer code and both these new observations with previously published data, we derive a new model of the planetary atmosphere. We have varied both the metallicity and C/O ratio in our modelling, and find no need for the extreme metallicity suggested by Sheppard et al. Our best-fitting models slightly underestimate the emission at i band and overestimate the observed flux at Ks band. To explain these discrepancies, we examine the impact on the planetary emission spectrum of the presence of several types of hazes which could form on the night side of the planet. Our Ks-band eclipse flux measurement is lower than expected from clear atmosphere models and this could be explained by haze particles larger than 0.2 mu m with the optical properties of Al2O3, CaTiO3 or MgSiO3. We find that z'-band measurements are important for understanding the contribution of photochemical hazes with particles smaller than 0.1 mu m at the top of the atmosphere.