63 research outputs found
Strategies for Imaging Faint Extended Sources in the Near-Infrared
Quantitative information about variations in the background at J and K' are
presented and used to develop guidelines for the acquisition and reduction of
ground-based images of faint extended sources in the near-infrared, especially
those which occupy a significant fraction of the field of view of a detector or
which are located in areas crowded with foreground or background sources.
Findings are based primarily upon data acquired over three photometric nights
with the 3.6x3.6 arcmin CFHT-IR array on the Canada-France-Hawaii Telescope
atop Mauna Kea. Although some results are specific to CFHT, overall conclusions
should be useful in guiding observing and reduction strategies of extended
objects elsewhere.Comment: Accepted for publication in PASP July 2004. 29 pages, including 2
tables and 9 figure
The dust environment of Main-Belt Comet P/2012 T1 (PANSTARRS)
Main-Belt Comet P/2012 T1 (PANSTARRS) has been imaged using the 10.4m Gran
Telescopio Canarias (GTC) and the 4.2m William Herschel Telescope (WHT) at six
epochs in the period from November 2012 to February 2013, with the aim of
monitoring its dust environment. The dust tails brightness and morphology are
best interpreted in terms of a model of sustained dust emission spanning 4 to 6
months. The total dust mass ejected is estimated at 6--25 kg.
We assume a time-independent power-law size distribution function, with
particles in the micrometer to centimeter size range. Based on the quality of
the fits to the isophote fields, an anisotropic emission pattern is favored
against an isotropic one, in which the particle ejection is concentrated toward
high latitudes ( to ) in a high obliquity object
(=80). This seasonally-driven ejection behavior, along with the
modeled particle ejection velocities, are in remarkable agreement to those we
found for P/2010 R2 (La Sagra) \citep{Moreno11a}.Comment: Accepted for publication in The Astrophysical Journal Letter
Deep K_s-near-infrared Surface Photometry of 80 Dwarf Irregular Galaxies in the Local Volume
We present deep near-infrared (K_s) images and surface photometry for 80 dwarf irregular galaxies (dIs) within ~5 Mpc of the Milky Way. The galaxy images were obtained at five different facilities between 2004 and 2006. The image reductions and surface photometry have been performed using methods specifically designed for isolating faint galaxies from the high and varying near-infrared sky level. Fifty-four of the 80 dIs have surface brightness profiles which could be fit to a hyperbolic-secant (sech) function, while the remaining profiles could be fit to the sum of a sech and a Gaussian function. From these fits, we have measured central surface brightnesses, scale lengths, and integrated magnitudes. This survey is part of a larger study of the connection between large-scale structure and the global properties of dIs, the hypothesized building-blocks of more massive galaxies
Deep Ks -near-infrared surface photometry of 80 dwarf irregular galaxies in the local volume
We present deep near-infrared (K_s) images and surface photometry for 80 dwarf irregular galaxies (dIs) within ~5 Mpc of the Milky Way. The galaxy images were obtained at five different facilities between 2004 and 2006. The image reductions and surface photometry have been performed using methods specifically designed for isolating faint galaxies from the high and varying near-infrared sky level. Fifty-four of the 80 dIs have surface brightness profiles which could be fit to a hyperbolic-secant (sech) function, while the remaining profiles could be fit to the sum of a sech and a Gaussian function. From these fits, we have measured central surface brightnesses, scale lengths, and integrated magnitudes. This survey is part of a larger study of the connection between large-scale structure and the global properties of dIs, the hypothesized building-blocks of more massive galaxies
Near-Earth Asteroids Data mining on Astronomical Databases: EuroNEAR experience
Program available at: http://www.imcce.fr/hosted_sites/naroo/program.htmlInternational audienceIn the framework of EuroNEAR network several databases around the world were datamined. The main scientifi c objective was the astrometry of Near-Earth Asteroids (NEAs) for both precovery and secure orbits of these objects. The article presents few aspects of data-mining and the developed procedures for accomplishing these objectives
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