5,635 research outputs found
How and Why to do VLBI on GPS
In order to establish the position of the center of mass of the Earth in the
International Celestial Reference Frame, observations of the Global Positioning
Satellite (GPS) constellation using the IVS network are important. With a good
frame-tie between the coordinates of the IVS telescopes and nearby GPS
receivers, plus a common local oscillator reference signal, it should be
possible to observe and record simultaneously signals from the astrometric
calibration sources and the GPS satellites. The standard IVS solution would
give the atmospheric delay and clock offsets to use in analysis of the GPS
data. Correlation of the GPS signals would then give accurate orbital
parameters of the satellites {\bf in the ICRF reference frame}, i.e. relative
to the positions of the astrometric sources. This is particularly needed to
determine motion of the center of mass of the earth along the rotation axis.Comment: 5 pages, 2 figures, Conference Proceedings - International Very Long
Baseline Service General Meeting 201
Milky Way Kinematics: Measurements at the Subcentral Point of the Fourth Quadrant
We use atomic hydrogen (HI) data from the Southern Galactic Plane Survey to
study the kinematics of the fourth quadrant of the Milky Way. By measuring the
terminal velocity as a function of longitude throughout the fourth Galactic
quadrant we have derived the most densely sampled rotation curve available for
the Milky Way between 3 < R < 8 kpc. We determine a new joint rotation curve
fit for the first and fourth quadrants, which can be used for kinematic
distances interior to the Solar circle. From our data we place new limits on
the peak to peak variation of streaming motions in the fourth quadrant to be
~10 km/s. We show that the shape of the average HI profile beyond the terminal
velocity is consistent with gas of three velocity dispersions, a cold component
with km/s, a warmer component with km/s and a
fast component with km/s. Examining the widths with Galactic
radius we find that the narrowest two components show little variation with
radius and their small scale fluctuations track each other very well,
suggesting that they share the same cloud-to-cloud motions. The width of the
widest component is constant until R<4 kpc, where it increases sharply.Comment: 36 pages, 10 figures, accepted to ApJ. Full electronic version of
table 1 available at
ftp://ftp.atnf.csiro.au/pub/people/nmcclure/papers/velocity_tab1.te
Review of Ruegen herring larvae survey project 2011
At the request of the Johann Heinrich von Thünen Institut (vTI), IOR Rostock, a return review of the German Rügen herring larval survey (RHLS) project took place on the 24th to 26th January 2011, following on from a similar review in November 2006. Mark Dickey-Collas (Wageningen IMARES) and Richard D.M. Nash (IMR, Norway) lead the review. This report represents the opinions of these two external reviewers. The current aim of the programme is to maintain and develop the time series of ichthyoplankton surveys in the spring and summer in the Greifswalder Bodden and stimulate spin off research. The review was designed to address the role of the survey in the framework of providing both management advice and research outputs. The external reviewers were given documents on the current survey. They also viewed presentations from research students and staff on their work and the proposed direction of the programme. The review included a “brainstorming” session on future research and potential gaps in the project
HI Emission and Absorption in the Southern Galactic Plane Survey
We present preliminary results from the Southern Galactic Plane Survey (SGPS)
Test Region and Parkes data. As part of the pilot project for the Southern
Galactic Plane Survey, observations of a Test Region (325.5 deg < l < 333.5
deg; -0.5 deg < b < 3.5 deg) were completed in December 1998. Single dish
observations of the full survey region (253 deg < l < 358 deg; |b| <1 deg) with
the Parkes Radio Telescope were completed in March 2000. We present a sample of
SGPS HI data with particular attention to the smallest and largest scale
structures seen in absorption and emission, respectively. On the large scale,
we detect many prominent HI shells. On the small scale, we note extremely
compact, cold clouds seen in HI self-absorption. We explore how these two
classes of objects probe opposite ends of the HI spatial power spectrum.Comment: 9 pages, 3 embedded postscript & 4 jpeg figures. Presented at the
Astronomical Society of Australia, Hobart, Tasmania, July 4-7 2000. To appear
in PASA Vol. 18(1
The Kennisbasis WOt Fisheries Programme carried out in 2010: Final Report
The KBWOT Fisheries programme is core to the maintenance and development of the expertise that underpins the statutory obligations of fisheries monitoring and advice for the Netherlands. As the WOT obligations of the Netherlands change over time, the KBWOT programme remains flexible and responsive to developments and innovations in methods and policy needs. The core principles of the programme are maintaining expertise whilst being forward looking, ensuring value for money and strong collaboration with client ministries. The programme operates through long term projects (multiannual) and annual projects in response to scientific and societal needs. The KBWOT fisheries programme must operate within the context of the reform of the common fisheries policy (CFP), the development of the EU marine strategy framework directive (MSFD) and the EU Maritime Policy
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