Differential astrometry measurements from the Palomar High-precision Astrometric Search for Exoplanet Systems have been combined with lower precision single-aperture measurements covering a much longer timespan (from eyepiece measurements, speckle interferometry, and adaptive optics) to determine improved visual orbits for 20 binary stars. In some cases, radial velocity observations exist to constrain the full three-dimensional orbit and determine component masses. The visual orbit of one of these binaries - {alpha} Com (HD 114378) - shows that the system is likely to have eclipses, despite its very long period of 26 years. The next eclipse is predicted to be within a week of 2015 January 24.
The Palomar High-precision Astrometric Search for Exoplanet Systems monitored 51 subarcsecond binary systems to evaluate whether tertiary companions as small as Jovian planets orbited either the primary or secondary stars, perturbing their otherwise smooth Keplerian motions. Six binaries are presented that show evidence of substellar companions orbiting either the primary or secondary star. Of these six systems, the likelihoods of two of the detected perturbations to represent real objects are considered to be "high confidence," while the remaining four systems are less certain and will require continued observations for confirmation.
The Palomar High-precision Astrometric Search for Exoplanet Systems (PHASES) monitored 51 subarcsecond binary systems to determine precision binary orbits, study the geometries of triple and quadruple star systems, and discover previously unknown faint astrometric companions as small as giant planets. PHASES measurements made with the Palomar Testbed Interferometer (PTI) from 2002 until PTI ceased normal operations in late 2008 are presented. Infrared differential photometry of several PHASES targets were measured with Keck Adaptive Optics and are presented.
In 2003-2004, we obtained 115 new observations of Phoebe, the 9th Saturnian faint satellite (visual magnitude of about 16.5). We used a large CCD detector (2048 x2048 pixels) mounted on the 1.56m astrometric reflector at the Sheshan Station, near Shanghai. In our reduction, an up-to-date catalogue of stars, UCAC2 (Zacharias et al., 2004, Cat. <I/289>), was chosen to ensure a proper astrometric calibration. A comparison of our observations to three recently available, high quality ephemerides, including the JPL SAT185 by Jacobson (SAT185, JPL satellite ephemeris), has shown that most of our observed positions of Phoebe present an accuracy of some tens of mas, which appears to be a very high level for such a faint satellite.
We present the results of the long-term uniform observations of visual double and multiple stars by 26-inch refractor. Set of observations (all plates) is measured with one measuring device for each star. For 259 pairs of visual double stars which were included in 194 systems, relative positions are calculated. For 127 pairs relative motions are also calculated. For 48 stars with well certain parallaxes from the Gipparkos catalog also the bottom limits for the total masses of systems are received under condition of the elliptic orbit is possible (dynamic mass). Comparison of accuracy of three measuring devices, which were applied to measurement of photographic plates, is executed. It is shown that differences in distances between the components, measured on the different measuring devices can reach 0.2" that proves advantage of uniform observations.
At the Engelhardt Astronomical Observatory (EAO), we observed photographic positions of 113 Galactic Radio Sources (GRS) in the system PPM catalogue (Rizvanov & Dautov, 1998, Kinematics and physics celestial bodies, 5, 457). Analysis of their accuracy is made by comparison with the Hipparcos catalogue (Perryman et al., 1997, Vat. <I/239>) and astrometric catalogue of radio stars in the radio window from the article of Walter et al. (1990A&AS...86..357W).
We describe a large database of photographic observations of Solar System bodies obtained at the Engelhadt Astronomical Observatory (EnAO). We give a brief description of the methods of observations and the accuracy of their reduction with the PPM and Tycho-2 catalogues. The photographic positions of the major planets, except Jupiter, are in the system of the Tycho-2 catalogue and their comparison with DE200 ephemeris coordinates are given.
We present the result of a planetary nebula (PN) survey of the nearby giant elliptical galaxy NGC 5128 performed with CCD cameras at the prime focus of the CTIO 4m in telescope. By comparing CCD images centered on the characteristic emission line [O III] {lambda}5007{AA} and on the adjacent continuum, we identify a total of 785 PNs in areas extending 20kpc along the photometric major axis and covering the whole galaxy to 10kpc. From these data, we form a complete sample of 224 PN's extending to a dereddened limiting magnitude of m_5007_=24.8, which extends 1.5mag down the PN luminosity function (PNLF). Adopting a foreground extinction of E(B-V)=0.1, we derive a distance to the galaxy of 3.5+/-0.2Mpc, in excellent agreement with the surface brightness fluctuation method. No population effect on the bright cutoff of PNLF is observed in the isophotal radius range of 2-16kpc, but the luminosity specific PN density ({alpha}_2.5_) seems to increase with radius inside of 7kpc, in agreement with the {alpha}_2.5_-color relation observed for other galaxies.
Based on a preliminary reference catalogue, combined with the catalogues PPM, ACRS and those in Eichhorn et al (1970, Cat. <I/90>), Jones (1973A&AS....9..313J) and Hertzsprung (1947AnLei..19a...1H), 33 exposures on 11 plates taken with the Zo-Se 40cm refractor (f=6895mm) in 86 years are reduced with the central overlapping technique, and high-precision positions and proper motions of 441 stars in the Pleiades astrometric standard region are obtained. The standard errors of star positions are less than +/-0.05arcsec, and the standard errors of proper motions for 90% stars in our reduction are less than +/-0.001arcsec/yr.
We present astrometric positions of Pluto, consistent with the International Celestial Reference System, from 4412 CCD frames observed over 120 nights with three telescopes at the Observatorio do Pico dos Dias in Brazil, covering a time span from 1995 to 2013, and also 145 frames observed over 11 nights in 2007 and 2009 with the ESO/MPG 2.2m telescope equipped with the Wide Field Imager (WFI). Our aim is to contribute to the study and improvement of the orbit of Pluto with new astrometric methods and positions.
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