In the far-infrared (FIR) / THz regime the angular (and often spectral) resolution of observing facilities is still very
restricted despite the fact that this frequency range has become of prime importance for modern astrophysics. ALMA
(Atacama Large Millimeter Array) with its superb sensitivity and angular resolution will only cover frequencies up to
about 1 THz, while the HIFI instrument for ESA'a Herschel Space Observatory will provide limited angular resolution
(10 to 30 arcsec) up to 2 THz. Observations of regions with star and planet formation require extremely high angular
resolution as well as frequency resolution in the full THz regime. In order to open these regions for high-resolution
astrophysics we present a study concept for a heterodyne space interferometer, ESPRIT (Exploratory Submm Space
Radio-Interferometric Telescope). This mission will cover the Terahertz regime inaccessible from the ground and outside
the operating range of the James Webb Space Telescope (JWST).
In the far-infrared (FIR) / THz regime the angular (and often spectral) resolution of observing facilities is still very restricted despite the fact that this frequency range has become of prime importance for modern astrophysics. ALMA (Atacama Large Millimeter Array) with its superb sensitivity and angular resolution will only cover frequencies up to about 1 THz, while the HIFI instrument for ESA'a Herschel Space Observatory will provide limited angular resolution (10 to 30 arcsec) up to 2 THz. Observations of regions with star and planet formation require extremely high angular resolution as well as frequency resolution in the full THz regime. In order to open these regions for high-resolution astrophysics we propose a heterodyne space interferometer mission, ESPRIT (Exploratory Submm Space Radio-Interferometric Telescope), for the Terahertz regime inaccessible from ground and outside the operating range of the James Webb Space Telescope (JWST).
The far-infrared (FIR) wavelength regime has become of prime importance for astrophysics. Observations of ionic, atomic and molecular lines, many of them present in the FIR, provide important and unique information on the star and planet formation process occurring in interstellar clouds, and on the lifecycle of gas and dust in general.
As these regions are heavily obscured by dust, FIR observations are the only means of getting insight in the physical and chemical conditions and their evolution. These investigations require, besides high spectral, also high angular resolution in order to match the small angular sizes of star forming cores and circum-stellar disks. We present here a mission concept, ESPRIT, which will provide both, in a wavelength regime not accessible from ground by ALMA (Atacama Large Millimeter Array), nor with JWST (James Webb Space Telescope).
KEYWORDS: Calibration, Phased arrays, Point spread functions, Polarization, Visibility, Global system for mobile communications, Synthetic apertures, Telescopes, Antennas, Electromagnetic coupling
The LOw Frequency ARray (LOFAR will observe at 20-200 MHz. At those frequencies, large ionospheric phase variations distort the observed brightness distribution. Fortunately, the imahe may be stabilized for long integrations by using bright radio sources in the sky. The downside is that LOFAR fields will be very crowded, which presents calibration challenges of its own. This is especially true for the bright and extended sources that enter via the relatively high sidelobes of the LOFAR station beams. An extra complication is that these beamshapes vary rather strongly in frequency and time. Altogether, LOFAR will require much more processing than existing radio telescopes, and has only just become possible with the new generation of computers. Even so, new processing techniques like 'peeling' had to be developed to speed things up by several orders of magnitude.
Calibrating SKA comes down to removing the effects of the many bright sources in the field. This can only be done in a closed-loop system, using a model of the observed brightness distribution. This implies an extension of the well-known 'self-calibration' technique to solve for 'image-plane' effects, i.e. instrumental effects that depend on the position in the field. In other words, we have to start solving for the detailed shape of the voltage beams of the individual stations. A distinction must be made between the treatment of the main lobe, and of the sidelobes of these beams. This paper investigates some of the boundary conditions of this approach, and formulates requirements for the accuracy and stability of SKA hardware.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.