28 research outputs found
A 1500 deg2 near infrared proper motion catalogue from the UKIDSS Large Area Survey
The United Kingdom Infrared Deep Sky Survey (UKIDSS) Large Area Survey (LAS) began in 2005, with the start of the UKIDSS programme as a 7 year effort to survey roughly 4000 deg2 at high Galactic latitudes in Y, J, H and K bands. The survey also included a significant quantity of two epoch J band observations, with an epoch baseline greater than 2 years to calculate proper motions. We present a near-infrared proper motion catalogue for the 1500 deg2 of the two epoch LAS data, which includes 135â625 stellar sources and a further 88â324 with ambiguous morphological classifications, all with motions detected above the 5Ï level. We developed a custom proper motion pipeline which we describe here. Our catalogue agrees well with the proper motion data supplied for a 300 deg2 subset in the current Wide Field Camera Science Archive (WSA) 10th data release (DR10) catalogue, and in various optical catalogues, but it benefits from a larger matching radius and hence a larger upper proper motion detection limit. We provide absolute proper motions, using LAS galaxies for the relative to absolute correction. By using local second-order polynomial transformations, as opposed to linear transformations in the WSA, we correct better for any local distortions in the focal plane, not including the radial distortion that is removed by the UKIDSS pipeline. We present the results of proper motion searches for new brown dwarfs and white dwarfs. We discuss 41 sources in the WSA DR10 overlap with our catalogue with proper motions >300âmasâyrâ1, several of which are new detections. We present 15 new candidate ultracool dwarf binary systems
HAT-P-14b: A 2.2Mj exoplanet transiting a bright F star
Original article can be found at: http://iopscience.iop.org/0004-637X/ Copyright American Astronomical Society. [Full text of this article is not available in the UHRA]We report the discovery of HAT-P-14b, a fairly massive transiting extrasolar planet orbiting the moderately bright star GSC 3086-00152 (V = 9.98), with a period of P = 4.627669 ± 0.000005 days. The transit is close to grazing (impact parameter 0.891+0.007 â0.008) and has a duration of 0.0912 ± 0.0017 days, with a reference epoch of mid-transit of Tc = 2, 454, 875.28938 ± 0.00047 (BJD). The orbit is slightly eccentric (e = 0.107 ± 0.013), and the orientation is such that occultations are unlikely to occur. The host star is a slightly evolved mid-F dwarf with a mass of 1.386 ± 0.045 M , a radius of 1.468 ± 0.054 R , effective temperature 6600 ± 90 K, and a slightly metal-rich composition corresponding to [Fe/H] = +0.11 ± 0.08. The planet has a mass of 2.232 ± 0.059 M J and a radius of 1.150 ± 0.052 R J, implying a mean density of 1.82 ± 0.24 g cmâ3. Its radius is well reproduced by theoretical models for the 1.3 Gyr age of the system if the planet has a heavy-element fraction of about 50 M â (7% of its total mass). The brightness, near-grazing orientation, and other properties of HAT-P-14 make it a favorable transiting system to look for changes in the orbital elements or transit timing variations induced by a possible second planet, and also to place meaningful constraints on the presence of sub-Earth mass or Earth-mass exomoons, by monitoring it for transit duration variations. [see original online version on journal webpage for correct notation]Peer reviewe
redMaPPer. I. ALGORITHM AND SDSS DR8 CATALOG
We describe redMaPPer, a new red-sequence cluster finder specifically
designed to make optimal use of ongoing and near-future large photometric
surveys. The algorithm has multiple attractive features: (1) It can iteratively
self-train the red-sequence model based on minimal spectroscopic training
sample, an important feature for high redshift surveys; (2) It can handle
complex masks with varying depth; (3) It produces cluster-appropriate random
points to enable large-scale structure studies; (4) All clusters are assigned a
full redshift probability distribution P(z); (5) Similarly, clusters can have
multiple candidate central galaxies, each with corresponding centering
probabilities; (6) The algorithm is parallel and numerically efficient: it can
run a Dark Energy Survey-like catalog in ~500 CPU hours; (7) The algorithm
exhibits excellent photometric redshift performance, the richness estimates are
tightly correlated with external mass proxies, and the completeness and purity
of the corresponding catalogs is superb. We apply the redMaPPer algorithm to
~10,000 deg^2 of SDSS DR8 data, and present the resulting catalog of ~25,000
clusters over the redshift range 0.08<z<0.55. The redMaPPer photometric
redshifts are nearly Gaussian, with a scatter \sigma_z ~ 0.006 at z~0.1,
increasing to \sigma_z~0.02 at z~0.5 due to increased photometric noise near
the survey limit. The median value for |\Delta z|/(1+z) for the full sample is
0.006. The incidence of projection effects is low (<=5%). Detailed performance
comparisons of the redMaPPer DR8 cluster catalog to X-ray and SZ catalogs are
presented in a companion paper (Rozo & Rykoff 2014).Comment: Accepted for publication in ApJ. The redMaPPer DR8 cluster catalog
and members are available at http://risa.stanford.edu/redmappe