10 research outputs found
A lidar for water vapour measurements in daytime at Lampedusa, Italy
ENEA is planning to develop a lidar system for measurement of the vertical profi le of water vapour mixing ratio
in daytime at a remote site, the Station for Climate Observations located in Lampedusa, Italy. The Raman lidar
technique has been retained because of its experimental simplicity with respect to DIAL, and the UV spectral
range has been chosen because Raman cross-sections and detector effi ciencies are larger. For a wavelength larger
than ~ 300 nm the signal is limited in daytime by sky background, but extinction is acceptable, and the aims of
the system can be reached with a strong laser source. The 355 nm wavelength of a frequency-tripled Nd:YAG
laser has been retained as this laser source permits to reach a large pulse energy while keeping the system simple
to operate. Geometrical form factor calculations need to be performed to evaluate the near-range overlap between
the laser beam and the fi eld-of-view of the receiver. Among several options, a dual-receiver system has been
retained to account for the several orders of magnitude expected in the backscattered signal intensity: a smaller
receiver, with a primary mirror of 200 mm diameter for the 0.2-1 km range, and a larger 500 mm receiver for the
1-3 km range
A lidar for water vapour measurements in daytime at Lampedusa, Italy
ENEA is planning to develop a lidar system for measurement of the vertical profi le of water vapour mixing ratio
in daytime at a remote site, the Station for Climate Observations located in Lampedusa, Italy. The Raman lidar
technique has been retained because of its experimental simplicity with respect to DIAL, and the UV spectral
range has been chosen because Raman cross-sections and detector effi ciencies are larger. For a wavelength larger
than ~ 300 nm the signal is limited in daytime by sky background, but extinction is acceptable, and the aims of
the system can be reached with a strong laser source. The 355 nm wavelength of a frequency-tripled Nd:YAG
laser has been retained as this laser source permits to reach a large pulse energy while keeping the system simple
to operate. Geometrical form factor calculations need to be performed to evaluate the near-range overlap between
the laser beam and the fi eld-of-view of the receiver. Among several options, a dual-receiver system has been
retained to account for the several orders of magnitude expected in the backscattered signal intensity: a smaller
receiver, with a primary mirror of 200 mm diameter for the 0.2-1 km range, and a larger 500 mm receiver for the
1-3 km range
Seeking the Local Convergence Depth. II. TF Observations of the Clusters A114, A119, A194, A2295, A2457, A2806, A3193, A3381, AND A3744
We present Tully-Fisher (TF) observations for nine rich Abell clusters of
galaxies. This is the second such data installment of an all-sky survey of 50
clusters in the redshift range 0.02 < z < 0.06. The data extends the TF study
of nearby clusters of Giovanelli et al.; they will be used jointly to determine
an accurate I band TF template and to establish a cluster inertial reference
frame to z = 0.06.Comment: 15 pages, uses AAS LaTeX, 3 tables and 9 postscript figures (only
first page of fig. 7 included in this version); to appear in the Astronomical
Journa
The Motions of Clusters of Galaxies and the Dipoles of the Peculiar Velocity Field
In preceding papers of this series, TF relations for galaxies in 24 clusters
with radial velocities between 1000 and 9200 km/s (SCI sample) were obtained, a
Tully-Fisher (TF) template relation was constructed and mean offsets of each
cluster with respect to the template obtained. Here, an estimate of the
line-of-sight peculiar velocities of the clusters and their associated errors
are given. It is found that cluster peculiar velocities in the Cosmic Microwave
Background reference frame do not exceed 600 k/ms and that their distribution
has a line-of-sight dispersion of 300 k/ms, suggesting a more quiescent cluster
peculiar velocity field than previously reported. When measured in a reference
frame in which the Local Group is at rest, the set of clusters at cz > 3000
km/s exhibits a dipole moment in agreement with that of the CMB, both in
amplitude and apex direction. It is estimated that the bulk flow of a sphere of
6000 km/s radius in the CMB reference frame is between 140 and 320 km/s. These
results are in agreement with those obtained from an independent sample of
field galaxies (Giovanelli et al. 1998; see astro-ph/9807274)Comment: 9 pages, 2 tables, 7 figures, uses AAS LaTex; to appear in A
The X-ray Cluster Dipole
We estimate the dipole of the whole sky X-ray flux-limited sample of
Abell/ACO clusters (XBACs) and compare it to the optical Abell/ACO cluster
dipole. The X-ray cluster dipole is well aligned () with the
CMB dipole, while it follows closely the radial profile of its optical cluster
counterpart although its amplitude is per cent lower. In view of
the fact that the the XBACs sample is not affected by the volume incompleteness
and the projection effects that are known to exist at some level in the optical
parent Abell/ACO cluster catalogue, our present results confirm the previous
optical cluster dipole analysis that there are significant contributions to the
Local Group motion from large distances (Mpc). In order to
assess the expected contribution to the X-ray cluster dipole from a purely
X-ray selected sample we compare the dipoles of the XBACs and the Brightest
Cluster Sample (Ebeling et al. 1997a) in their overlap region. The resulting
dipoles are in mutual good aggreement with an indication that the XBACs sample
slightly underestimates the full X-ray dipole (by per cent) while the
Virgo cluster contributes about 10 - 15 per cent to the overall X-ray cluster
dipole. Using linear perturbation theory to relate the X-ray cluster dipole to
the Local group peculiar velocity we estimate the density parameter to be
.Comment: 16 pages, latex, + 4 ps figures, submitted to Ap
A lidar for water vapour measurements in daytime at Lampedusa, Italy
ENEA is planning to develop a lidar system for measurement of the vertical profi le of water vapour mixing ratio in daytime at a remote site, the Station for Climate Observations located in Lampedusa, Italy. The Raman lidar technique has been retained because of its experimental simplicity with respect to DIAL, and the UV spectral range has been chosen because Raman cross-sections and detector effi ciencies are larger. For a wavelength larger than ~ 300 nm the signal is limited in daytime by sky background, but extinction is acceptable, and the aims of the system can be reached with a strong laser source. The 355 nm wavelength of a frequency-tripled Nd:YAG laser has been retained as this laser source permits to reach a large pulse energy while keeping the system simple to operate. Geometrical form factor calculations need to be performed to evaluate the near-range overlap between the laser beam and the fi eld-of-view of the receiver. Among several options, a dual-receiver system has been retained to account for the several orders of magnitude expected in the backscattered signal intensity: a smaller receiver, with a primary mirror of 200 mm diameter for the 0.2-1 km range, and a larger 500 mm receiver for the 1-3 km range
The cluster velocity field
none6siopenMoscardini L.; BRANCHINI, ENZO FRANCO; Brunozzi P. Tini; Borgani S.; Plionis M.; Coles P.Moscardini, L.; Branchini, ENZO FRANCO; Brunozzi P., Tini; Borgani, S.; Plionis, M.; Coles, P