26 research outputs found
QSO Absorbing Galaxies at z<~1: Deep Imaging and Spectroscopy in the Field of 3C 336
We present very deep WFPC2 images and FOS spectroscopy from the Hubble Space
Telescope (HST) together with numerous supporting ground-based observations of
the field of the quasar 3C 336 (). The observations are designed
to investigate the nature of galaxies producing metal line absorption systems
in the spectrum of the QSO. Along a single line of sight, we find at least 6
metal line absorption systems (of which 3 are newly discovered) ranging in
redshift from 0.317 to 0.892. Through an extensive program of optical and IR
imaging, QSO spectroscopy, and faint galaxy spectroscopy, we have identified 5
of the 6 metal line absorption systems with luminous (L_K > 0.1 L*_K) galaxies.
These have morphologies ranging from very late-type spiral to S0, and exhibit a
wide range of inclination and position angles with respect to the QSO
sightline. The only unidentified absorber, despite our intensive search, is a
damped Lyman system at . Analysis of the absorption
spectrum suggests that the metal abundances ([Fe/H]) in this system are
similar to those in damped systems at , and to the two other damped
systems for which abundances have been determined at . We have found no
examples of intrinsically faint galaxies () at small impact
parameters that might have been missed as absorber candidates in our previous
ground-based imaging and spectroscopic programs on MgII absorbing galaxies.
There are no bright galaxies (L > 0.1 L_K) within 50h^{-1} kpc which do not
produce detectable metal lines (of Mg II 2796, 2803 and/or C IV 1548, 1550) in
the QSO spectrum. All of these results generally support the inferences which
we have previously reached from a larger survey for absorption-selected
galaxies at z\simlt 1.Comment: 32 pages latex (AAS v4.0 style). 8 Postscript figures (including HST
plate) available at ftp://astro.caltech.edu/users/ccs/3c336_figs.ps.gz .
Submitted to Ap
GNOSIS: the first instrument to use fibre Bragg gratings for OH suppression
GNOSIS is a prototype astrophotonic instrument that utilizes OH suppression
fibres consisting of fibre Bragg gratings and photonic lanterns to suppress the
103 brightest atmospheric emission doublets between 1.47-1.7 microns. GNOSIS
was commissioned at the 3.9-meter Anglo-Australian Telescope with the IRIS2
spectrograph to demonstrate the potential of OH suppression fibres, but may be
potentially used with any telescope and spectrograph combination. Unlike
previous atmospheric suppression techniques GNOSIS suppresses the lines before
dispersion and in a manner that depends purely on wavelength. We present the
instrument design and report the results of laboratory and on-sky tests from
commissioning. While these tests demonstrated high throughput and excellent
suppression of the skylines by the OH suppression fibres, surprisingly GNOSIS
produced no significant reduction in the interline background and the
sensitivity of GNOSIS and IRIS2 is about the same as IRIS2. It is unclear
whether the lack of reduction in the interline background is due to physical
sources or systematic errors as the observations are detector noise-dominated.
OH suppression fibres could potentially impact ground-based astronomy at the
level of adaptive optics or greater. However, until a clear reduction in the
interline background and the corresponding increasing in sensitivity is
demonstrated optimized OH suppression fibres paired with a fibre-fed
spectrograph will at least provide a real benefits at low resolving powers.Comment: 15 pages, 13 figures, accepted to A
GNOSIS: The first instrument to use fiber bragg gratings for OH suppression
The near-infrared is an important part of the spectrum in astronomy, especially in cosmology because the light from objects in the early universe is redshifted to these wavelengths. However, deep near-infrared observations are extremely difficult to makeThe GNOSIS team acknowledges funding by ARC LIEF
grant LE100100164. C.Q.T. gratefully acknowledges support by the National
Science Foundation Graduate Research Fellowship under grant
No. DGE-1035963
Brazilian Consensus on Photoprotection
Brazil is a country of continental dimensions with a large heterogeneity of climates and massive mixing of the population. Almost the entire national territory is located between the Equator and the Tropic of Capricorn, and the Earth axial tilt to the south certainly makes Brazil one of the countries of the world with greater extent of land in proximity to the sun. The Brazilian coastline, where most of its population lives, is more than 8,500 km long. Due to geographic characteristics and cultural trends, Brazilians are among the peoples with the highest annual exposure to the sun. Epidemiological data show a continuing increase in the incidence of nonmelanoma and melanoma skin cancers. Photoprotection can be understood as a set of measures aimed at reducing sun exposure and at preventing the development of acute and chronic actinic damage. Due to the peculiarities of Brazilian territory and culture, it would not be advisable to replicate the concepts of photoprotection from other developed countries, places with completely different climates and populations. Thus the Brazilian Society of Dermatology has developed the Brazilian Consensus on Photoprotection, the first official document on photoprotection developed in Brazil for Brazilians, with recommendations on matters involving photoprotection
Searching for consensus in the approach to patients with chronic lateral ankle instability: ask the expert
The purpose of this study is to propose recommendations for the treatment of patients with chronic lateral ankle instability (CAI) based on expert opinions.status: accepte