3,368 research outputs found
XMM-Newton and Deep Optical Observations of the OTELO fields: the Groth-Westphal Strip
OTELO (OSIRIS Tunable Emission Line Object Survey) will be carried out with
the OSIRIS instrument at the 10 m GTC telescope at La Palma, and is aimed to be
the deepest and richest survey of emission line objects to date. The deep
narrow-band optical data from OSIRIS will be complemented by means of
additional observations that include: (i) an exploratory broad-band survey that
is already being carried out in the optical domain, (ii) FIR and sub-mm
observations to be carried with the Herschel space telescope and the GTM, and
(iii) deep X-Ray observations from XMM-Newton and Chandra.Here we present a
preliminary analysis of public EPIC data of one of the OTELO targets,the
Groth-Westphal strip, gathered from the XMM-Newton Science Archive (XSA). EPIC
images are combined with optical BVRI data from our broadband survey carried
out with the 4.2m WHT at La Palma. Distance-independent diagnostics (involving
X/O ratio, hardness ratios, B/T ratio) are tested.Comment: 2 pages, 2 figures, uses graphicx package. To appear in proceedings
of "The X-Ray Universe 2005", San Lorenzo del Escorial, Spain, September
26-30, 200
Rentabilidad económica de explotaciones agrarias de secano según tamaño y tipo de laboreo
RESUMEN: El objetivo de este trabajo es evaluar, desde un punto de vista económico, el efecto que supone pasar de un sistema de laboreo tradicional a uno de laboreo reducido en explotaciones cerealistas de la meseta castellana. Se utilizan datos experimentales de campo para estimar las producciones, asà como un sistema de decisión experto para seleccionar el parque de maquinaria que conlleva el menor coste de utilización. La rotación de cultivos que se ha considerado ha sido trigo/leguminosa. No se encontraron diferencias significativas entre los rendimientos obtenidos en los tres sistemas de laboreo comparados. Los resultados económicos se muestran condicionados por el sistema de laboreo empleado y el tamaño de la explotación.Economic analyses, farm size, rainfed crops, tillage systems, Agricultural and Food Policy, Q12,
Red quasars not so dusty
Webster et al (1995) claimed that up to 80% of QSOs may be obscured by dust.
They inferred the presence of this dust from the remarkably broad range of B-K
optical-infrared colours of a sample of flat-spectrum PKS radio QSOs. If such
dust is typical of QSOs, it will have rendered invisible most of those which
would otherwise been have detected by optical surveys. We used the William
Herschel Telescope on La Palma to obtain K infrared images of 54 B3 radio
quasars selected at low frequency (mainly steep-spectrum), and we find that
although several have very red optical-infrared colours, most of these can be
attributed to an excess of light in K rather than a dust-induced deficit in B.
We present evidence that some of the infrared excess comes from the light of
stars in the host galaxy (some, as previously suggested, comes from synchrotron
radiation associated with flat-spectrum radio sources). The B-K colours of the
B3 QSOs provide no evidence for a large reddened population. Either the Webster
et al QSOs are atypical in having such large extinctions, or their reddening is
not due to dust; either way, the broad range of their B-K colours does not
provide evidence that a large fraction of QSOs has been missed from optical
surveys.Comment: 16 pages TeX file + 2 PostScript figures. Accepted in MNRA
K-band imaging of 52 B3-VLA quasars: Nucleus and host properties
We present K-band imaging and photometry of a sample of 52 radio loud quasars
(RQs) selected from the B3 survey with flux densities above 0.5 Jy at 408 MHz.
The optical completeness of the sample is 90% and the quasars cover the
redshift range 0.4 - 2.3. For ~57% of the sources for which the quality of the
images allowed a detailed morphological study (16/28) resolved extended
emission was detected around the QSO, and its K flux was measured. Interpreting
this ``fuzz'' as starlight emission from the host galaxy, its location on the
K-z plane at z<1 is consistent with radio quasars being hosted by galaxies
similar to radio galaxies (RGs) or giant ellipticals (gEs). At higher redshifts
the detected host galaxies of RQs are more luminous than typical RGs and gEs,
although some weak detections or upper limits are consistent with a similar
fraction of RQs being hosted by galaxies with the expected luminosities for RGs
or gEs. We found a significant correlation between radio power and nuclear
infrared luminosity indicating a direct link between the radio synchrotron
emission and the nuclear emission in K. This correlation is more tight for the
steep-spectrum sources (99.97% significance). In addition, a trend is found
between radio power and infrared luminosity of the host galaxy (or mass), in
the sense that the most powerful quasars inhabit the most luminous galaxies.Comment: tar gzipped file including 1 LaTeX file, 4 latex tables, and 13
PostScript figures. Accepted in AJ (April 1998
The thromboaspiration with INDIGO system reduces the time and dose of fibrinolysis and improves the results in massive pulmonary embolism in comparison with catheter fragmentation (previous cohort study)
Purpose: Determine if thromboaspiration with indigo system improves short- and medium-term outcomes compared with interventional treatment of choice for pulmonary embolism (PE) (mechanical thrombolysis + catheter-directed thrombolytic therapy)
Early Science with the Large Millimetre Telescope: Molecules in the Extreme Outflow of a proto-Planetary Nebula
Extremely high velocity emission likely related to jets is known to occur in
some proto-Planetary Nebulae. However, the molecular complexity of this
kinematic component is largely unknown. We observed the known extreme outflow
from the proto-Planetary Nebula IRAS 16342-3814, a prototype water fountain, in
the full frequency range from 73 to 111 GHz with the RSR receiver on the Large
Millimetre Telescope. We detected the molecules SiO, HCN, SO, and CO.
All molecular transitions, with the exception of the latter are detected for
the first time in this source, and all present emission with velocities up to a
few hundred km s. IRAS 16342-3814 is therefore the only source of this
kind presenting extreme outflow activity simultaneously in all these molecules,
with SO and SiO emission showing the highest velocities found of these species
in proto-Planetary Nebulae. To be confirmed is a tentative weak SO component
with a FWHM 700 km s. The extreme outflow gas consists of dense
gas (n 10--10 cm), with a mass larger than
0.02--0.15 M. The relatively high abundances of SiO and SO may
be an indication of an oxygen-rich extreme high velocity gas.Comment: Accepted for publication in Monthly Notices of the Royal Astronomical
Society Letter
OSIRIS Software: The Mask Designer Tool
OSIRIS is a Day One instrument that will be available at the 10m GTC
telescope which is being built at La Palma observatory in the Canary Islands.
This optical instrument is designed to obtain wide-field narrow-band images
using tunable filters and to do low-resolution spectroscopy in both long-slit
and multislit modes. For the multislit spectroscopy mode, we have developed a
software to assist the observers to design focal plane masks. In this paper we
describe the characteristics of this Mask Designer tool. We discuss the main
design concepts, the functionality and particular features of the software.Comment: 6 figures; accepted for publication in Experimental Astronom
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