29,819 research outputs found
The IRAC Dark Field; Far- Infrared to X-ray Data
We present 20 band photometry from the far-IR to X-ray in the Spitzer IRAC
dark field. The bias for the near-IR camera on Spitzer is calibrated by
observing a ~20 arcminute diameter "dark" field near the north ecliptic pole
roughly every two-to-three weeks throughout the mission duration of Spitzer.
The field is unique for its extreme depth, low background, high quality
imaging, time-series information, and accompanying photometry including data
taken with Akari, Palomar, MMT, KPNO, Hubble, and Chandra. This serendipitous
survey contains the deepest mid-IR data taken to date. This dataset is well
suited for studies of intermediate redshift galaxy clusters, high redshift
galaxies, the first generation of stars, and the lowest mass brown dwarfs,
among others. This paper provides a summary of the data characteristics and
catalog generation from all bands collected to date as well as a discussion of
photometric redshifts and initial and expected science results and goals. To
illustrate the scientific potential of this unique dataset, we also present
here IRAC color color diagrams.Comment: 12 pages, ApJS accepte
HARP/ACSIS: A submillimetre spectral imaging system on the James Clerk Maxwell Telescope
This paper describes a new Heterodyne Array Receiver Programme (HARP) and
Auto-Correlation Spectral Imaging System (ACSIS) that have recently been
installed and commissioned on the James Clerk Maxwell Telescope (JCMT). The
16-element focal-plane array receiver, operating in the submillimetre from 325
to 375 GHz, offers high (three-dimensional) mapping speeds, along with
significant improvements over single-detector counterparts in calibration and
image quality. Receiver temperatures are 120 K across the whole band and
system temperatures of 300K are reached routinely under good weather
conditions. The system includes a single-sideband filter so these are SSB
figures. Used in conjunction with ACSIS, the system can produce large-scale
maps rapidly, in one or more frequency settings, at high spatial and spectral
resolution. Fully-sampled maps of size 1 square degree can be observed in under
1 hour.
The scientific need for array receivers arises from the requirement for
programmes to study samples of objects of statistically significant size, in
large-scale unbiased surveys of galactic and extra-galactic regions. Along with
morphological information, the new spectral imaging system can be used to study
the physical and chemical properties of regions of interest. Its
three-dimensional imaging capabilities are critical for research into
turbulence and dynamics. In addition, HARP/ACSIS will provide highly
complementary science programmes to wide-field continuum studies, and produce
the essential preparatory work for submillimetre interferometers such as the
SMA and ALMA.Comment: MNRAS Accepted 2009 July 2. 18 pages, 25 figures and 6 table
Ultradeep Near-Infrared ISAAC Observations of the HDF-S: Observations, Reduction, Multicolor Catalog, and Photometric Redshifts
We present deep near-infrared (NIR) Js, H, and Ks-band ISAAC imaging of the
WFPC2 field of the HDF-S. The 2.5'x 2.5' high Galactic latitude field was
observed with the VLT under the best seeing conditions with integration times
amounting to 33.6 hours in Js, 32.3 hours in H, and 35.6 hours in Ks. We reach
total AB magnitudes for point sources of 26.8, 26.2, and 26.2 respectively (3
sigma), which make it the deepest ground-based NIR observations to date, and
the deepest Ks-band data in any field. The effective seeing of the coadded
images is ~0.45" in Js, ~0.48" in H, and ~0.46" in Ks. Using published WFPC2
optical data, we constructed a Ks-limited multicolor catalog containing 833
sources down to Ks,tot ~< 26 (AB), of which 624 have seven-band optical-to-NIR
photometry. These data allow us to select normal galaxies from their rest-frame
optical properties to high redshift (z ~< 4). The observations, data reduction
and properties of the final images are discussed, and we address the detection
and photometry procedures that were used in making the catalog. In addition, we
present deep number counts, color distributions and photometric redshifts of
the HDF-S galaxies. We find that our faint Ks-band number counts are flatter
than published counts in other deep fields, which might reflect cosmic
variations or different analysis techniques. Compared to the HDF-N, we find
many galaxies with very red V-H colors at photometric redshifts 1.95 < z < 3.5.
These galaxies are bright in Ks with infrared colors redder than Js-Ks > 2.3
(in Johnson magnitudes). Because they are extremely faint in the observed
optical, they would be missed by ultraviolet-optical selection techniques, such
as the U-dropout method.Comment: LaTeX, 24 pages, 15 figures, 3 tables. Accepted for publication in
the Astronomical Journal. The paper with full resolution images and figures
is available at http://www.strw.leidenuniv.nl/~fires/papers/2002Labbe.ps.gz .
The reduced data and catalogs can be found at
http://www.strw.leidenuniv.nl/~fires/data/hdfs
The Hubble Legacy Archive NICMOS Grism Data
The Hubble Legacy Archive (HLA) aims to create calibrated science data from
the Hubble Space Telescope archive and make them accessible via user-friendly
and Virtual Observatory (VO) compatible interfaces. It is a collaboration
between the Space Telescope Science Institute (STScI), the Canadian Astronomy
Data Centre (CADC) and the Space Telescope - European Coordinating Facility
(ST-ECF). Data produced by the Hubble Space Telescope (HST) instruments with
slitless spectroscopy modes are among the most difficult to extract and
exploit. As part of the HLA project, the ST-ECF aims to provide calibrated
spectra for objects observed with these HST slitless modes. In this paper, we
present the HLA NICMOS G141 grism spectra. We describe in detail the
calibration, data reduction and spectrum extraction methods used to produce the
extracted spectra. The quality of the extracted spectra and associated direct
images is demonstrated through comparison with near-IR imaging catalogues and
existing near-IR spectroscopy. The output data products and their associated
metadata are publicly available through a web form at http://hla.stecf.org and
via VO interfaces. In total, 2470 spectra of 1923 unique targets are included
in the current release.Comment: 18 pages, 21 figures, accepted for publication in Astronomy &
Astrophysic
The Astro-WISE approach to quality control for astronomical data
We present a novel approach to quality control during the processing of
astronomical data. Quality control in the Astro-WISE Information System is
integral to all aspects of data handing and provides transparent access to
quality estimators for all stages of data reduction from the raw image to the
final catalog. The implementation of quality control mechanisms relies on the
core features in this Astro-WISE Environment (AWE): an object-oriented
framework, full data lineage, and both forward and backward chaining. Quality
control information can be accessed via the command-line awe-prompt and the
web-based Quality-WISE service. The quality control system is described and
qualified using archive data from the 8-CCD Wide Field Imager (WFI) instrument
(http://www.eso.org/lasilla/instruments/wfi/) on the 2.2-m MPG/ESO telescope at
La Silla and (pre-)survey data from the 32-CCD OmegaCAM instrument
(http://www.astro-wise.org/~omegacam/) on the VST telescope at Paranal.Comment: Accepted for publication in topical issue of Experimental Astronomy
on Astro-WISE information syste
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
Deep u*- and g-band Imaging of the Spitzer Space Telescope First Look Survey Field : Observations and Source Catalogs
We present deep u*-, and g-band images taken with the MegaCam on the 3.6 m
Canada-France-Hawaii Telescope (CFHT) to support the extragalactic component of
the Spitzer First Look Survey (hereafter, FLS). In this paper we outline the
observations, present source catalogs and characterize the completeness,
reliability, astrometric accuracy and number counts of this dataset. In the
central 1 deg2 region of the FLS, we reach depths of g~26.5 mag, and u*~26.2
mag (AB magnitude, 5 detection over a 3" aperture) with ~4 hours of
exposure time for each filter. For the entire FLS region (~5 deg2 coverage), we
obtained u*-band images to the shallower depth of u*=25.0--25.4 mag (5,
3" aperture). The average seeing of the observations is 0.85" for the central
field, and ~1.00" for the other fields. Astrometric calibration of the fields
yields an absolute astrometric accuracy of 0.15" when matched with the SDSS
point sources between 18<g<22. Source catalogs have been created using
SExtractor. The catalogs are 50% complete and greater than 99.3% reliable down
to g~26.5 mag and u*~26.2 mag for the central 1 deg2 field. In the shallower
u*-band images, the catalogs are 50% complete and 98.2% reliable down to
24.8--25.4 mag. These images and source catalogs will serve as a useful
resource for studying the galaxy evolution using the FLS data.Comment: 15 pages, 16 figure
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