647 research outputs found
Brorfelde Schmidt CCD Catalog (BSCC)
The Brorfelde Schmidt CCD Catalog (BSCC) contains about 13.7 million stars,
north of +49 deg Declination with precise positions and V, R photometry. The
catalog has been constructed from the reductions of 18,667 CCD frames observed
with the Brorfelde Schmidt Telescope between 2000 and 2007. The Tycho-2 catalog
was used for astrometric and photometric reference stars. Errors of individual
positions are about 20 to 200 mas for stars in the R = 10 to 18 mag range.
External comparisons with 2MASS and SDSS reveal possible small systematic
errors in the BSCC of up to about 30 mas. The catalog is supplemented with J,
H, and K_s magnitudes from the 2MASS catalog. The catalog data file (about 550
MB ASCII, compressed) will be made available at the Strasbourg Data Center
(CDS).Comment: 16 pages, 22 figures, 2 tables, accepted by A
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Effects of associative (sequential) learning across speech perception, speech production, reading, and typing
Reconsidering the galactic coordinate system
Initially defined by the IAU in 1958, the galactic coordinate system was
thereafter in 1984 transformed from the B1950.0 FK4-based system to the J2000.0
FK5-based system. In 1994, the IAU recommended that the dynamical reference
system FK5 be replaced by the ICRS, which is a kinematical non-rotating system
defined by a set of remote radio sources. However the definition of the
galactic coordinate system was not updated. We consider that the present
galactic coordinates may be problematic due to the unrigorous transformation
method from the FK4 to the FK5, and due to the non-inertiality of the FK5
system with respect to the ICRS. This has led to some confusions in
applications of the galactic coordinates. We tried to find the transformation
matrix in the framework of the ICRS after carefully investigating the
definition of the galactic coordinate system and transformation procedures,
however we could not find a satisfactory galactic coordinate system that is
connected steadily to the ICRS. To avoid unnecessary misunderstandings, we
suggest to re-consider the definition of the galactic coordinate system which
should be directly connected with the ICRS for high precise observation at
micro-arcsecond level.Comment: 10 pages, 3 figures, accepted for publication in A&
Spectral Energy Distributions of Type 1 AGN in the COSMOS Survey I - The XMM-COSMOS Sample
The "Cosmic Evolution Survey" (COSMOS) enables the study of the Spectral
Energy Distributions (SEDs) of Active Galactic Nuclei (AGN) because of the deep
coverage and rich sampling of frequencies from X-ray to radio. Here we present
a SED catalog of 413 X-ray (\xmm) selected type 1 (emission line FWHM km
s) AGN with Magellan, SDSS or VLT spectrum. The SEDs are corrected for
the Galactic extinction, for broad emission line contributions, constrained
variability, and for host galaxy contribution. We present the mean SED and the
dispersion SEDs after the above corrections in the rest frame 1.4 GHz to 40
keV, and show examples of the variety of SEDs encountered. In the near-infrared
to optical (rest frame -- 4000\AA), the photometry is complete for
the whole sample and the mean SED is derived from detections only. Reddening
and host galaxy contamination could account for a large fraction of the
observed SED variety. The SEDs are all available on-line.Comment: 22 pages, 22 figures, ApJ accepted, scheduled to be published October
20th, 2012, v75
A catalogue of bright (K <9) M dwarfs
Using the Position and Proper Motion Extended-L (PPMXL) catalogue, we have used optical and near-infrared colour cuts together with a reduced proper motion cut to find bright M dwarfs for future exoplanet transit studies. PPMXL's low proper motion uncertainties allow us to probe down to smaller proper motions than previous similar studies. We have combined unique objects found with this method to that of previous work to produce 8479 K <9 M dwarfs. Low-resolution spectroscopy was obtained of a sample of the objects found using this selection method to gain statistics on their spectral type and physical properties. Results show a spectral-type range of K7-M4V. This catalogue is the most complete collection of K <9 M dwarfs currently available and is made available here.Peer reviewe
X-ray and Near-infrared Studies of a Star-forming Cloud; L1448
We present the results of X-ray and near-infrared (NIR) observations of
L1448, a star-forming region in the Perseus cloud complex using the Chandra
X-ray Observatory and the 4 m telescope at the Kitt Peak National Observatory.
We detect 72 X-ray sources in a ~17 arcmin x 17 arcmin region with a ~68 ks
ACIS exposure, for which we conduct follow-up NIR imaging observations in a
concentric ~11 arcmin x 11 arcmin region with FLAMINGOS down to m_Ks ~ 17 mag.
Twelve X-ray sources have NIR or optical counterparts. By plotting X-ray mean
energy versus NIR to X-ray flux ratio, the X-ray sources are clearly separated
into two groups. The X-ray spectral and temporal features as well as NIR
magnitudes and colors indicate that one group mainly consists of young stellar
objects (YSOs) in the cloud and the other of background extragalactic sources.
Ten X-ray-emitting YSO candidates are thus newly identified, which are low-mass
or brown dwarf mass sources from their NIR magnitudes. In addition, a possible
X-ray signal is found from a mid-infrared protostar L1448 IRS 3(A). The lack of
detection of this source in our deep NIR images indicates that this source has
a very steep spectral slope of > 3.2 in 2--10 micron.Comment: 13 pages, 7 postscript figures, accepted for publication in A
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