34 research outputs found
Quantifying Non-circular Streaming Motions in Disc Galaxies
High-quality velocity maps of galaxies frequently exhibit signatures of
non-circular streaming motions. We here apply the software tool, "velfit"
recently proposed by Spekkens & Sellwood, to five representative galaxies from
the THINGS sample. We describe the strengths and weaknesses of the tool, and
show that it is both more powerful and yields results that are more easily
interpreted than the commonly used procedure. We demonstrate that it can
estimate the magnitudes of forced non-circular motions over a broad range of
bar strengths from a strongly barred galaxy, through cases of mild bar-like
distortions to placing bounds on the shapes of halos in galaxies having
extended rotation curves. We identify mild oval distortions in the inner parts
of two dwarf galaxies, NGC 2976 and NGC 7793, and show that the true strength
of the non-axisymmetric gas flow in the strongly barred galaxy NGC 2903 is
revealed more clearly in our fit to an optical Halpha map than to the neutral
hydrogen data. The method can also yield a direct estimate of the ellipticity
of a slowly-rotating potential distortion in the flat part of a rotation curve,
and we use our results to place tight bounds on the possible ellipticity of the
outer halos of NGC 3198 and NGC 2403.Comment: 12 pages, 8 color figures, to appear in MNRAS. Version 2 of the
software can be downloaded from
http://www.physics.rutgers.edu/~spekkens/velfit
All Sky Camera, LIDAR and Electric Field Meter: auxiliary instruments for the ASTRI SST-2M prototype
ASTRI SST-2M is the end-to-end prototype telescope of the Italian National
Institute of Astro- physics, INAF, designed to investigate the 10-100 TeV band
in the framework of the Cherenkov Telescope Array, CTA. The ASTRI SST-2M
telescope has been installed in Italy in September 2014, at the INAF ob-
serving station located at Serra La Nave on Mount Etna. The telescope is
foreseen to be completed and fully operative in spring 2015 including auxiliary
instrumentation needed to support both operations and data anal- ysis. In this
contribution we present the current status of a sub-set of the auxiliary
instruments that are being used at the Serra La Nave site, namely an All Sky
Camera, an Electric Field Meter and a Raman Lidar devoted, together with
further instrumentation, to the monitoring of the atmospheric and environmental
conditions. The data analysis techniques under development for these
instruments could be applied at the CTA sites, where similar auxiliary
instrumentation will be installed.Comment: Proceedings of the 2nd AtmoHEAD Conference, Padova (Italy) May 19-21,
201
TOSC: an algorithm for the tomography of spotted transit chords
Photometric observations of planetary transits may show localized bumps,
called transit anomalies, due to the possible crossing of photospheric
starspots. The aim of this work is to analyze the transit anomalies and derive
the temperature profile inside the transit belt along the transit direction. We
develop the algorithm TOSC, a tomographic inverse-approach tool which, by means
of simple algebra, reconstructs the flux distribution along the transit belt.
We test TOSC against some simulated scenarios. We find that TOSC provides
robust results for light curves with photometric accuracies better than 1~mmag,
returning the spot-photosphere temperature contrast with an accuracy better
than 100~K. TOSC is also robust against the presence of unocculted spots,
provided that the apparent planetary radius given by the fit of the transit
light curve is used in place of the true radius. The analysis of real data with
TOSC returns results consistent with previous studies
SOXS Optical Design
The report describes the optical design of the Son Of X-Shooter (SOXS) intrument for the NTT ESO telescope, presented at the instrument Optical FD
Development status of the UV-VIS detector system of SOXS for the ESO-NTT telescope
SOXS will be the new spectroscopic facility for the ESO NTT telescope able to
cover the optical and NIR bands by using two different arms: the UV-VIS
(350-850 nm), and the NIR (800-2000 nm). In this article, we describe the
development status of the visible camera cryostat, the architecture of the
acquisition system and the progress in the electronic design. The UV-VIS
detector system is based on a CCD detector 44-82 from e2v, a custom detector
head, coupled with the ESO continuous flow cryostats (CFC), a custom cooling
system, based on a Programmable Logic Controller (PLC), and the New General
Controller (NGC) developed by ESO. This paper outlines the development status
of the system, describes the design of the different parts that make up the
UV-VIS arm and is accompanied by a series of information describing the SOXS
design solutions in the mechanics and in the electronics parts. The first tests
of the detector system with the UV-VIS camera will be shown.Comment: 10 pager, 13 figure
TARJETA DE VISITA [Material gráfico]
EUROPACopia digital. Madrid : Ministerio de Educación, Cultura y Deporte, 201