84 research outputs found
ESO for GOODS' sake
Currently public ESO data sets pertinent to the CDFS/GOODS field are briefly
illustrated along with an indication on how to get access to them. Future ESO
plans for complementing the GOODS database with optical/IR imaging and optical
spectroscopy are also described.Comment: 6 pages, 2 figures, to appear in the proceedings of the ESO/USM
Workshop "The Mass of Galaxies at Low and High Redshift" (Venice, Italy,
October 2001), eds. R. Bender and A. Renzin
Cleaning sky survey databases using Hough Transform and Renewal String approaches
Large astronomical databases obtained from sky surveys such as the
SuperCOSMOS Sky Survey (SSS) invariably suffer from spurious records coming
from artefactual effects of the telescope, satellites and junk objects in orbit
around earth and physical defects on the photographic plate or CCD. Though
relatively small in number these spurious records present a significant problem
in many situations where they can become a large proportion of the records
potentially of interest to a given astronomer. Accurate and robust techniques
are needed for locating and flagging such spurious objects, and we are
undertaking a programme investigating the use of machine learning techniques in
this context. In this paper we focus on the four most common causes of unwanted
records in the SSS: satellite or aeroplane tracks, scratches, fibres and other
linear phenomena introduced to the plate, circular halos around bright stars
due to internal reflections within the telescope and diffraction spikes near to
bright stars. Appropriate techniques are developed for the detection of each of
these. The methods are applied to the SSS data to develop a dataset of spurious
object detections, along with confidence measures, which can allow these
unwanted data to be removed from consideration. These methods are general and
can be adapted to other astronomical survey data.Comment: Accepted for MNRAS. 17 pages, latex2e, uses mn2e.bst, mn2e.cls,
md706.bbl, shortbold.sty (all included). All figures included here as low
resolution jpegs. A version of this paper including the figures can be
downloaded from http://www.anc.ed.ac.uk/~amos/publications.html and more
details on this project can be found at
http://www.anc.ed.ac.uk/~amos/sattrackres.htm
ESO Imaging Survey: infrared observations of CDF-S and HDF-S
This paper presents infrared data obtained from observations carried out at
the ESO 3.5m New Technology Telescope (NTT) of the Hubble Deep Field South
(HDF-S) and the Chandra Deep Field South (CDF-S). These data were taken as part
of the ESO Imaging Survey (EIS) program, a public survey conducted by ESO to
promote follow-up observations with the VLT. In the HDF-S field the infrared
observations cover an area of ~53 square arcmin, encompassing the HST WFPC2 and
STIS fields, in the JHKs passbands. The seeing measured in the final stacked
images ranges from 0.79" to 1.22" and the median limiting magnitudes (AB
system, 2" aperture, 5sigma detection limit) are J_AB~23.0, H_AB~22.8 and
K_AB~23.0 mag. Less complete data are also available in JKs for the adjacent
HST NICMOS field. For CDF-S, the infrared observations cover a total area of
\~100 square arcmin, reaching median limiting magnitudes (as defined above) of
J_AB~23.6 and K_AB~22.7 mag. For one CDF-S field H-band data are also
available. This paper describes the observations and presents the results of
new reductions carried out entirely through the un-supervised, high-throughput
EIS Data Reduction System and its associated EIS/MVM C++-based image processing
library developed, over the past 5 years, by the EIS project and now publicly
available. The paper also presents source catalogs extracted from the final
co-added images which are used to evaluate the scientific quality of the survey
products, and hence the performance of the software. This is done comparing the
results obtained in the present work with those obtained by other authors from
independent data and/or reductions carried out with different software packages
and techniques. The final science-grade catalogs and co-added images are
available at CDS.Comment: Accepted for publication in A&A, 13 pages, 12 figures; a full
resolution version of the paper is available from
http://www.astro.ku.dk/~lisbeth/eisdata/papers/4528.pdf ; related catalogs
and images are available through http://www.astro.ku.dk/~lisbeth/eisdata
The circumstellar envelope of IRC+10216 from milli-arcsecond to arcmin scales
Aims.Analysis of the innermost regions of the carbon-rich star IRC+10216 and
of the outer layers of its circumstellar envelope have been performed in order
to constrain its mass-loss history. Methods: .We analyzed the high dynamic
range of near-infrared adaptive optics and the deep V-band images of the
circumstellar envelope of IRC+10216 using high angular resolution, collected
with the VLT/NACO and FORS1 instruments. Results: .From the near-infrared
observations, we present maps of the sub-arcsecond structures, or clumps, in
the innermost regions. The morphology of these clumps is found to strongly vary
from J- to L-band. Their relative motion appears to be more complex than
proposed in earlier works: they can be weakly accelerated, have a constant
velocity, or even be motionless with respect to one another. From V-band
imaging, we present a high spatial resolution map of the shell distribution in
the outer layers of IRC+10216. Shells are resolved well up to a distance of
about 90'' to the core of the nebula and most of them appear to be composed of
thinner elongated shells. Finally, by combining the NACO and FORS1 images, a
global view is present to show both the extended layers and the bipolar core of
the nebula together with the real size of the inner clumps. Conclusions: .This
study confirms the rather complex nature of the IRC+10216 circumstellar
environment. In particular, the coexistence at different spatial scales of
structures with very different morphologies (clumps, bipolarity, and almost
spherical external layers) is very puzzling. This confirms that the formation
of AGB winds is far more complex than usually assumed in current models.Comment: Published in Astronomy & Astrophysics, 2006, 455, 18
ESO Imaging Survey. The Stellar Catalogue in the Chandra Deep Field South
(abridged) Stellar catalogues in five passbands (UBVRI) over an area of
approximately 0.3 deg^2, comprising about 1200 objects, and in seven passbands
(UBVRIJK) over approximately 0.1 deg^2, comprising about 400 objects, in the
direction of the Chandra Deep Field South are presented.
The 90% completeness level of the number counts is reached at approximately U
= 23.8, B = 24.0, V = 23.5, R = 23.0, I = 21.0, J = 20.5, K = 19.0.
A scheme is presented to select point sources from these catalogues, by
combining the SExtractor parameter CLASS_STAR from all available passbands.
Probable QSOs and unresolved galaxies are identified by using the previously
developed \chi^2-technique (Hatziminaoglou et al 2002), that fits the overall
spectral energy distributions to template spectra and determines the best
fitting template.
The observed number counts, colour-magnitude diagrams, colour-colour diagrams
and colour distributions are presented and, to judge the quality of the data,
compared to simulations based on the predictions of a Galactic Model convolved
with the estimated completeness functions and the error model used to describe
the photometric errors of the data.
The resulting stellar catalogues and the objects identified as likely QSOs
and unresolved galaxies with coordinates, observed magnitudes with errors and
assigned spectral types by the -technique are presented and are
publicly available.Comment: Paper as it will appear in print. Complete figures and tables can be
obtained from: http://www.eso.org/science/eis/eis_pub/eis_pub.html. Astronomy
& Astrophysics, accepted for publicatio
ESO Imaging Survey: Optical follow-up of 12 selected XMM-Newton fields
(Abridged) This paper presents the data recently released for the
XMM-Newton/WFI survey carried out as part of the ESO Imaging Survey (EIS)
project. The aim of this survey is to provide optical imaging follow-up data in
BVRI for identification of serendipitously detected X-ray sources in selected
XMM-Newton fields. In this paper, fully calibrated individual and stacked
images of 12 fields as well as science-grade catalogs for the 8 fields located
at high-galactic latitude are presented. The data covers an area of \sim 3
square degrees for each of the four passbands. The median limiting magnitudes
(AB system, 2" aperture, 5\sigma detection limit) are 25.20, 24.92, 24.66, and
24.39 mag for B-, V-, R-, and I-band, respectively. These survey products,
together with their logs, are available to the community for science
exploitation in conjunction with their X-ray counterparts. Preliminary results
from the X-ray/optical cross-correlation analysis show that about 61% of the
detected X-ray point sources in deep XMM-Newton exposures have at least one
optical counterpart within 2" radius down to R \simeq 25 mag, 50% of which are
so faint as to require VLT observations thereby meeting one of the top
requirements of the survey, namely to produce large samples for spectroscopic
follow-up with the VLT, whereas only 15% of the objects have counterparts down
to the DSS limiting magnitude.Comment: 24 pages, 10 figures, accepted for publication in Astronomy and
Astrophysics. Accompanying data releases available at
http://archive.eso.org/archive/public_datasets.html (WFI images),
http://www.eso.org/science/eis/surveys/release_65000025_XMM.html (optical
catalogs), http://www.aip.de/groups/xray/XMM_EIS/ (X-ray data). Full
resolution version available at
http://www.astro.uni-bonn.de/~dietrich/publications/3785.ps.g
ESO Imaging Survey. Deep Public Survey: Multi-Color Optical Data for the Chandra Deep Field South
This paper presents multi-passband optical data obtained from observations of
the Chandra Deep Field South (CDF-S), located at alpha ~ 3h 32m, delta ~ -27d
48m. The observations were conducted at the ESO/MPG 2.2m telescope at La Silla
using the 8kx8k Wide-Field Imager (WFI). This data set, taken over a period of
one year, represents the first field to be completed by the ongoing Deep Public
Survey (DPS) being carried out by the ESO Imaging Survey (EIS) project. This
paper describes the optical observations, the techniques employed for
un-supervised pipeline processing and the general characteristics of the final
data set. The paper includes data taken in six different filters U'UBVRI. The
data cover an area of about 0.25 square degrees reaching 5 sigma limiting
magnitudes of U'_AB=26.0, U_AB=25.7, B_AB=26.4$, V_AB=25.4, R_AB=25.5 and I_AB=
24.7 mag, as measured within a 2xFWHM aperture. The optical data covers the
area of ~ 0.1Comment: 13 pages, 19 postscript figures, Figure 3,4,7,10 are available in
jpeg format, use aa.cls style. The full postscript of the paper is available
at http://www.eso.org/science/eis/eis_pub/eis_pub.htm
Pre-FLAMES Survey: Observations of Selected Stellar Fields
This paper presents the first set of fully calibrated images and associated
stellar catalogs of the Pre-FLAMES survey being carried out by the ESO Imaging
Survey (EIS) project. The primary goal of this survey is to provide the ESO
community with data sets from which suitable target lists can be extracted for
follow-up observations with the new VLT facility FLAMES. For this purpose 160
stellar fields have been selected for observations in B, V and I using the
8kx8k Wide Field Imager (WFI) at the MPG/ESO 2.2 m telescope at La Silla. These
data have been used to assess the observing strategy adopted and to define
suitable reduction techniques and procedures for the preparation of input
catalogs for FLAMES. The images and catalogs presented here are publicly
available and can be requested from the URL address ``http://www.eso.org/eis''.Comment: 18 pages, 28 figures available in gif format. The postscript version
of the paper with all the figures encapsulated is available at
http://www.eso.org/science/eis/eis_pub/eis_pub.html. Astronomy &
Astrophysics, accepte
RFID Tracking of Sublethal Effects of Two Neonicotinoid Insecticides on the Foraging Behavior of Apis mellifera
The development of insecticides requires valid risk assessment procedures to avoid causing harm to beneficial insects and especially to pollinators such as the honeybee Apis mellifera. In addition to testing according to current guidelines designed to detect bee mortality, tests are needed to determine possible sublethal effects interfering with the animal's vitality and behavioral performance. Several methods have been used to detect sublethal effects of different insecticides under laboratory conditions using olfactory conditioning. Furthermore, studies have been conducted on the influence insecticides have on foraging activity and homing ability which require time-consuming visual observation. We tested an experimental design using the radiofrequency identification (RFID) method to monitor the influence of sublethal doses of insecticides on individual honeybee foragers on an automated basis. With electronic readers positioned at the hive entrance and at an artificial food source, we obtained quantifiable data on honeybee foraging behavior. This enabled us to efficiently retrieve detailed information on flight parameters. We compared several groups of bees, fed simultaneously with different dosages of a tested substance. With this experimental approach we monitored the acute effects of sublethal doses of the neonicotinoids imidacloprid (0.15–6 ng/bee) and clothianidin (0.05–2 ng/bee) under field-like circumstances. At field-relevant doses for nectar and pollen no adverse effects were observed for either substance. Both substances led to a significant reduction of foraging activity and to longer foraging flights at doses of ≥0.5 ng/bee (clothianidin) and ≥1.5 ng/bee (imidacloprid) during the first three hours after treatment. This study demonstrates that the RFID-method is an effective way to record short-term alterations in foraging activity after insecticides have been administered once, orally, to individual bees. We contribute further information on the understanding of how honeybees are affected by sublethal doses of insecticides
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