M. A. C. Perryman

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Context. Empirical evidence suggests a tantalising but unproven link between various indicators of solar activity and the barycentric motion of the Sun. The latter is exemplified by transitions between regular and more disordered motion modulated by the motions of the giant planets, and rare periods of retrograde motion with negative orbital angular(More)
We use absolute trigonometric parallaxes from the Hipparcos Catalogue to determine individual distances to members of the Hyades cluster, from which the 3-dimensional structure of the cluster can be derived. Inertially-referenced proper motions are used to rediscuss distance determinations based on convergent-point analyses. A combination of parallaxes and(More)
The Gaia mission is designed as a Galaxy explorer, and will measure simultaneously, in a survey mode, the five or six phase space parameters of all stars brighter than 20th magnitude, as well as providing a description of their astrophysical characteristics. These measurements are obtained by combining an astrometric instrument with micro-arcsecond(More)
Fig, 1: Detection methods for extra-solar planets, The lower extent of the lines indicates, roughly, the detectable masses that are in principle within reach of present measurements (solid lines), and those that might be expected within the next 10-20 years (dashed), The (logarithmic) mass scale is shown at left, The miscellaneous signatures to the upper(More)
Context. At about 1000 days after the launch of Gaia we present the first Gaia data release, Gaia DR1, consisting of astrometry and photometry for over 1 billion sources brighter than magnitude 20.7. Aims. A summary of Gaia DR1 is presented along with illustrations of the scientific quality of the data, followed by a discussion of the limitations due to the(More)
We present observations of 11 quasars, selected in the range z ≈ 2.2–4.1, obtained with ESA's Superconducting Tunnel Junction (STJ) camera on the WHT. Using a single template QSO spectrum, we show that we can determine the redshifts of these objects to about 1%. A follow-up spectroscopic observation of one QSO for which our best-fit redshift (z = 2.976)(More)
S-Cam is a cryogenic camera for ground-based astronomy using superconducting tunnel junctions (STJ's). It has been designed as a technology demonstrator, aiming to prove the potential of a new generation of single photon-counting detectors at a ground-based telescope. The camera is based on a 6/spl times/6 array of Ta-Al Josephson junctions, operating at(More)
We present high time-resolution optical energy-resolved photometry of the eclipsing cataclysmic variable V2301 Oph made using the ESA S-Cam detector, an array of photon counting super-conducting tunnel junction (STJ) devices with intrinsic energy resolution. Three eclipses were observed, revealing considerable variation in the eclipse shape, particularly(More)
We report the first observations of an astronomical object using a superconducting tunnel junction (STJ) device, a pixel detector with intrinsic energy resolution in the optical wavelength range. The Crab pulsar was observed using a 6 × 6 array of Tantalum STJs at the 4.2-m William Herschel Telescope on La Palma. Each array element provides photon counting(More)
A combination of absolute trigonometric parallaxes and proper motions from Hipparcos, and radial velocities from ground-based observations, are used to determine the position and velocity components of candidate members with respect to the Hyades cluster centre, providing new information on cluster membership. The 3-dimensional structure of the cluster is(More)