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Ftaclas, C.

Publications and source records attributed to Ftaclas, C..

11 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS2003

Artemis: A Stratospheric Planet Finder

The near-space environment of the stratosphere is far superior to terrestrial sites for optical and infrared observations. New balloon technologies will enable flights and safe recovery of 2-ton payloads at altitudes of 35 km for 100 days and longer. The combination of long flights and superb observing conditions make it possible to undertake science programs that otherwise could only be done from orbit. We propose to fly an "Ultra-Hubble" Stratospheric Telescope (UHST) equipped with a coronagraphic camera and active optics at 35 km to search for planets around 200 of the nearest stars. This ULDB mission will establish the frequency of solar-type planetary systems, and provide targets to search for earth-like planets.

Ford, H. C.↗
NASA NTRS1997

Simulations of the STIS CCD clear imaging mode PSF

Detailed understanding of the properties of the point-spread function (PSF) of Space Telescope Imaging Spectrograph (STIS) imaging modes is necessary to separate real effects of geometrically complex astronomical sources, such as protoplanetary disks surrounding bright stars, from instrumental effects, such as scattering and diffraction. In order to investigate STIS imaging properties we have numerically simulated broadband stellar PSFs generated by STIS in CCD clear imaging mode, including the effects of the Lyot stop and the coronagraphic wedges. The input spectrum is a stellar model atmosphere of the appropriate spectral type, convolved with the pre-flight STIS CCD response function. The PSF modeler generates broadband PSFs by co-adding weighted monochromatic PSFs across the waveband.

Cornett, R. H.↗
NASA NTRS1994

The Astrometric Imaging Telescope Optical System

This oral presentation describes the Astrometric Imaging Telescope as a space-based observatory designed to detect and study planetary systems and circumstellar material around hundreds of nearby stars.

N/A↗
NASA NTRS1994

The Astrometric Imaging Telescope Optical System

The Astrometric Imaging Telescope will detect extra-solar planetary systems with imaging and astrometry. The optical system contains a high-efficiency coronagraph and scatter-compensated mirrors to detect Jupiter-size planets around nearby stars.

Astrometric Imaging↗
NASA NTRS1994

Modelling of a space-based Ronchi ruling experiment for high-precision astrometry

An end-to-end modelling program for an astrometric telescope employing a Ronchi ruling has been developed. The program models the aberrated images formed anywhere in the field-of-view. It then determines apparent centroids by simulating the motion of a Ronchi ruling across the field. Photo-electron statistics are included. A 6-term plate-constant model is used to determine the apparent motion of a target star within a reference frame as the object is re-observed through both ideal and perturbed optics. The modelling code is accurate at the submicroarcsecond level. optics. The modelling code is accurate at the submicroarcsecond level.

Shaklan, S.↗
NASA NTRS1992

Polarization sensitivity analysis of an earth remote sensing instrument - The MODIS-N phase B study

Polarization analysis software that employs Jones matrix formalism to calculate the polarization sensitivity of an instrument design was developed at Hughes Danbury Optical Systems. The code is capable of analyzing the full ray bundle at its angles of incidence for each optical surface. Input is based on the system ray trace and the thin film coating design at each surface. The MODIS-N (Moderate Resolution Imaging Spectrometer) system is used to demonstrate that it is possible to meet stringent requirements on polarization insensitivity associated with planned remote sensing instruments. Analysis indicates that a polarization sensitivity less than or equal to 2 percent was achieved in all desired spectral bands at all pointing angles, per specification. Polarization sensitivities were as high as 10 percent in similar remote sensing instruments.

Waluschka, E.↗
NASA NTRS1989

Fabrication experiments on supersmooth optics for extrasolar planet detection

The direct detection of extrasolar planets by imaging will require reductions in scattered and diffracted light by factors in excess of 1000 within one arcsecond of a bright source. While diffraction can be reduced by a number of approaches, small angle scatter can only be reduced by controlling midspatial frequency figure errors. The surface requirements are reviewed and their meaning when compared to the data base of existing mirrors is considered. Experiments are discribed that were successful in reducing midspatial frequency figure so that the scatter level was 500 times less than diffraction for a 25-cm spherical mirror.

Ftaclas, C.↗