Astrometric positions of the five largest satellites are given for the oppositions of Uranus for the years 1989 to 1994. These positions were measured on 368 CCD frames obtained at the Cassegrain focus of a 1.6-m reflector. They are compared with the theoretically calculated positions from GUST86 (Laskar & Jacobson 1987). The observed minus calculated residuals referred to Oberon have standard deviations of the order of 0.05" for the three greatest Uranian satellites and 0.07" for Miranda. These residuals are comparable to the best available in the literature.
In this paper, we publish measurements of 864 positions of the major satellites of Uranus made in 1995-1997 using CCD (1024"*1024") detectors attached to the 1.56-metre Astrometric Telescope at the Sheshan station near Shanghai. Analysis of the data as inter-satellite positions shows that the observations of Ariel, Umbriel, Titania and Mirand relative to Oberon have root-mean-square residuals of 0.03"-0.05", except for the innermost and faintest satellite Miranda, whose residuals exceeded 0.08" due to the proximity of Uranus.
Catalogs of 145 astrometric positions of Uranus and 4 its moons U1-U4 and 62 positions of Neptune and Triton have been compiled with Tycho-2 as a reference frame from photographic observations obtained at the Main Astronomical Observatory, National Academy of Sciences of Ukraine, in 1963-1990. Astronegatives have been digitized with an Epson Expression 10000XL commercial scanner in 16-bit grayscale with a resolution of 1200 dpi. Reduction has been performed in the LINUX-MIDAS-ROMAFOT software supplemented with additional modules for the precise positional determination. The internal positional accuracy of the reduction is 0.04-0.25" for both coordinates and 0.21-0.65m for photographic magnitudes of the Tycho-2 catalog. Gallery of plate images used for catalogs: http://gua.db.ukr-vo.org/catalog_gallery.php?catn=neptun_1963_1990 http://gua.db.ukr-vo.org/catalog_gallery.php?catn=uran_1963_1990
Accurate positional measurements of planets and satellites are used to improve their orbits, our knowledge of their dynamics and to infer the accuracy of the planet and satellite ephemerides. In the framework of the European FP7 ESPaCE program, we provide the positions of Mars, Phobos, and Deimos taken with the U.S. Naval Observatory 61-inch astrometric reflector and 26-inch refractor from 1967 to 1997. 425 astrophotographic plates were measured with the digitizer of the Royal Observatory of Belgium and reduced through an optimal process which includes image, instrumental, and spherical corrections using the UCAC4 catalog to provide the most accurate equatorial (RA, DEC) positions.
Accurate positional measurements of planets and satellites are used to improve our knowledge of both their orbits and their dynamics and to infer the accuracy of the planet and satellite ephemerides. In the framework of the European FP7 ESPaCE program, we provide the positions of Saturn and its major satellites taken with the U.S. Naval Observatory 26-inch refractor from 1974 to 1998. 526 astrophotographic plates were measured with the digitizer of the Royal Observatory of Belgium and reduced through an optimal process that includes image, instrumental, and spherical corrections using the UCAC4 catalog to provide the most accurate equatorial (RA, DEC) positions.
Variations in stellar flux can potentially overwhelm the photometric signal of a transiting planet. Such variability has not previously been well-characterized in the ultraviolet lines used to probe the inflated atmospheres surrounding hot Jupiters. Therefore, we surveyed 38 F-M stars for intensity variations in four narrow spectroscopic bands: two enclosing strong lines from species known to inhabit hot Jupiter atmospheres, C.II {lambda}{lambda}1334, 1335 and SiIII{lambda}1206; one enclosing SiIV {lambda}{lambda}1393, 1402; and 36.5{AA} of interspersed continuum. For each star/band combination, we generated 60s cadence lightcurves from archival Hubble Space Telescope Cosmic Origins Spectrograph and Space Telescope Imaging Spectrograph time-tagged photon data. Within these lightcurves, we characterized flares and stochastic fluctuations as separate forms of variability. Flares: we used a cross-correlation approach to detect 116 flares. These events occur in the time-series an average of once per 2.5hr, over 50% last 4 minutes or less, and most produce the strongest response in SiIV. If the flare occurred during a transit measurement integrated for 60 minutes, 90/116 would destroy the signal of an Earth, 27/116 Neptune, and 7/116 Jupiter, with the upward bias in flux ranging from 1% to 109% of quiescent levels. Fluctuations: photon noise and underlying stellar fluctuations produce scatter in the quiescent data. We model the stellar fluctuations as Gaussian white noise with standard deviation {sigma}_x_. Maximum likelihood values of {sigma}_x_ range from 1% to 41% for 60s measurements. These values suggest that many cool stars will only permit a transit detection to high confidence in ultraviolet resonance lines if the radius of the occulting disk is >~1R_J_. However, for some M dwarfs this limit can be as low as several R_{oplus}_.
The Kilodegree Extremely Little Telescope (KELT) project is a small aperture, wide-angle search for planetary transits of solar-type stars. In this paper, we present the results of a commissioning campaign with the KELT telescope to observe the open cluster Praesepe for 34 nights in early 2005. Light curves were obtained for 69337 stars, out of which we identify 58 long-period variables and 152 periodic variables. Sixteen of these are previously known as variable, yielding 194 newly discovered variable stars for which we provide properties and light curves. We also searched for planetary-like transits, finding four transit candidates. Follow-up observations indicate that two of the candidates are astrophysical false positives, with two candidates remaining as potential planetary transits.
We present seven new transiting hot Jupiters from the WASP-South survey. The planets are all typical hot Jupiters orbiting stars from F4 to K0 with magnitudes of V=10.3-12.5. The orbital periods are all in the range of 3.9-4.6d, the planetary masses range from 0.4 to 2.3-M_Jup_ and the radii from 1.1 to 1.4R_Jup_. In line with known hot Jupiters, the planetary densities range from Jupiter-like to inflated ({rho}=0.13-1.07{rho}_Jup_). We use the increasing numbers of known hot Jupiters to investigate the distribution of their orbital periods and the 3-4d 'pile-up'.
We report the discovery of a new stellar companion in the KOI-13 system. KOI-13 is composed of two fast-rotating A-type stars of similar magnitude. One of these two stars hosts a transiting planet discovered by Kepler. We obtained new radial velocity measurements using the SOPHIE spectrograph at the Observatoire de Haute-Provence that reveal an additional companion in this system. This companion has a mass of between 0.4M_{sun}_ and 1M_{sun}_ and orbits one of the two main stars with a period of 65.831+/-0.029-days and an eccentricity of 0.52+/-0.02.
We report the discovery of a hot Jupiter transiting a subgiant star with an orbital period of 6.87-days thanks to public photometric data from the Kepler space mission and new radial velocity observations obtained by the SOPHIE spectrograph. The planet KOI-428b with a radius of 1.17+/-0.04R_Jup_ and a mass of 2.2+/-0.4M_Jup_, orbits around a F5IV star with R*=2.13+/-0.06R_{sun}_, M*=1.48+/-0.06M_{sun} and Teff=6510+/-100K. The star KOI-428 is the largest and the most evolved star discovered so far with a transiting planet
