15 research outputs found
A radio continuum survey of the southern sky at 1420 MHz. Observations and data reduction
We describe the equipment, observational method and reduction procedure of an
absolutely calibrated radio continuum survey of the South Celestial Hemisphere
at a frequency of 1420 MHz. These observations cover the area 0h < R.A. < 24h
for declinations less than -10 degree. The sensitivity is about 50 mK T_B (full
beam brightness) and the angular resolution (HPBW) is 35.4', which matches the
existing northern sky survey at the same frequency.Comment: 9 pages with 9 figures, A&A, in pres
TRIS I: Absolute Measurements of the Sky Brightness Temperature at 0.6, 0.82 and 2.5 GHz
At frequencies close to 1 GHz the sky diffuse radiation is a superposition of
radiation of Galactic origin, the 3 K Relic or Cosmic Microwave Background
Radiation, and the signal produced by unresolved extragalactic sources. Because
of their different origin and space distribution the relative importance of the
three components varies with frequency and depends on the direction of
observation. With the aim of disentangling the components we built TRIS, a
system of three radiometers, and studied the temperature of the sky at , and GHz using geometrically scaled antennas
with identical beams (HPBW = ). Observations
included drift scans along a circle at constant declination
which provided the dependence of the sky signal on the
Right Ascension, and absolute measurement of the sky temperature at selected
points along the same scan circle. TRIS was installed at Campo Imperatore (lat.
= N, long.= , elevation = 2000 m a.s.l.) in
Central Italy, close to the Gran Sasso Laboratory.Comment: Accepted for publication in The Astrophysical Journa
A joint study of early and late spectral distortions of the cosmic microwave background and of the millimetric foreground
We have compared the absolute temperature data of the CMB spectrum with
models for CMB spectra distorted by a single or two heating processes at
different cosmic times. The constraints on the fractional energy injected in
the radiation field, DE/E, are mainly provided by the FIRAS instrument aboard
the COBE satellite. Under the hypothesis that two heating processes have
occurred at different epochs, the limits on DE/E are relaxed by a factor 2 both
for the earlier and the later process with respect to the case in which a
single energy injection in the thermal history of the universe is considered.
In general, the constraints on DE/E are weaker for early processes than for
relatively late processes, because of the wavelength coverage of FIRAS data.
We considered also the FIRAS calibration as revised by Battistelli et al.
2000, that, in the case of the favourite calibrator emissivity law proposed by
the authors, implies significant deviations from a planckian spectrum. An
astrophysical explanation of this, although intriguing, seems difficult, both
in terms of CMB spectral distortions and in terms of a relevant millimetric
foreground.
Future precise measurements at longer wavelengths as well as current and
future CMB anisotropy space missions will provide independent, direct or
indirect, cross checks.Comment: 24 pages, 8 figures; includes improvements in response to refere
report. Accepted for publication on MNRA
The unseen water: Experimentation with scientific photomicrography and creative coding
This research involves aesthetic approaches to scientific photomicrography. Specifically, this project investigates the reinterpretation of photomicrographic images of micro-scale drops of water made by a Scanning Electron Microscope (SEM), a tool that has expanded the boundaries of observation and representation of the micro world since it was introduced to scientific research in the mid-1960s. I was not aiming to produce scientific records through my use of the SEM; instead, like several artists before me, I used scientific photography methods to create aesthetic images. By exploring the interplay between the indexical and iconic modalities in the process of creating photomicrographs, I seek to imbue them with new meanings and re-appropriate scientific photography as a creative practice and a source of science communication to the general public. Building on the fact that scientific and digital tools have brought new ways of seeing the world, my artistic application of them seeks to extend our perception. This paper provides an explanation of the production of interactive artworks for my project. In these works, viewers are encouraged to engage with photomicrographs of water through touch and movement, which resembles human interaction with water