1,512 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
Identification of new cataclysmic variables in the 1RXS and USNO-B1.0 catalogs
As a result of applying the original optical variability search method on
publicly available data, we have found eight new cataclysmic variables and two
possible Optically Violent Variable quasars among the previously unidentified
X-ray sources in the ROSAT catalog. We describe the search method and present
the characteristics of the newly identified variable stars. The obtained
results demonstrate the large potential of the concept of Virtual Observatory
for identifying new objects of astrophysical interest.Comment: 16 pages, 11 figures, 2 tables; submitted to Astronomy Letter
Disentangling flows in the solar transition region
The measured average velocities in solar and stellar spectral lines formed at
transition region temperatures have been difficult to interpret. However,
realistic three-dimensional radiation magnetohydrodynamics (3D rMHD) models of
the solar atmosphere are able to reproduce the observed dominant line shifts
and may thus hold the key to resolve these issues. Our new 3D rMHD simulations
aim to shed light on how mass flows between the chromosphere and corona and on
how the coronal mass is maintained. Passive tracer particles, so-called corks,
allow the tracking of parcels of plasma over time and thus the study of changes
in plasma temperature and velocity not only locally, but also in a co-moving
frame. By following the trajectories of the corks, we can investigate mass and
energy flows and understand the composition of the observed velocities. Our
findings show that most of the transition region mass is cooling. The
preponderance of transition region redshifts in the model can be explained by
the higher percentage of downflowing mass in the lower and middle transition
region. The average upflows in the upper transition region can be explained by
a combination of both stronger upflows than downflows and a higher percentage
of upflowing mass. The most common combination at lower and middle transition
region temperatures are corks that are cooling and traveling downward. For
these corks, a strong correlation between the pressure gradient along the
magnetic field line and the velocity along the magnetic field line has been
observed, indicating a formation mechanism that is related to downward
propagating pressure disturbances. Corks at upper transition region
temperatures are subject to a rather slow and highly variable but continuous
heating process.Comment: 13 pages, 10 figures, online movi
Making Sense of Hip Preservation Procedural Coding--Getting Paid for Your Work!
Hip preservation and peri-trochanteric procedures are becoming more commonplace for the arthroplasty surgeon. Understanding the reimbursement for these procedures remains a challenge for those looking to expand this portion of their practice. In order to financially maximize the surgeon’s efforts, we present recommendations for hip preservation procedural coding
Revisiting the Parallax of the Isolated Neutron Star RX J185635-3754 Using HST/ACS Imaging
We have redetermined the parallax and proper motion of the nearby isolated
neutron star RX~J185635-3754. We used eight observations with the high
resolution camera of the HST/ACS taken from 2002 through 2004. We performed the
astrometric fitting using five independent methods, all of which yielded
consistent results. The mean estimate of the distance is 123 (+11, -15) pc (1
sigma), in good agreement with our earlier published determination
Cassini ISS mutual event astrometry of the mid-sized Saturnian satellites 2005-2012
Reproduced with permission from Astronomy & Astrophysics, © ES
Molecular Beams
Contains research objectives and reports on four research projects.Lincoln Laboratory, Purchase Order DDL B-00306U. S. ArmyU. S. NavyU. S. Air Force under Air Force Contract AF19(604)-740
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