scholarly journals The Use of the Hubble Space Telescope for Global Reference Frame Work

1986 ◽  
Vol 7 ◽  
pp. 87-88
Author(s):  
P. D. Hemenway
Keyword(s):  
Transfer Functions ◽  
Hubble Space Telescope ◽  
Field Of View ◽  
Optimum Conditions ◽  
Small Aperture ◽  
Space Telescope ◽  
Frame Work ◽  
Global Reference Frame ◽  
Better Than ◽  
Small Field Of View

The Hubble Space Telescope (HST) will have the capability of making relative astrometric measurements with an accuracy of four to ten times better than similar ground based measurements. The instruments of choice will be the Fine Guidance Sensors (FGS’s). Details of the instrumentation have been given elsewhere (c.f. Jefferys, 1980). Each FGS consists of two interferometer detectors which look at a small aperture located within a larger field of view (FOV). The raw data consist of encoder readings, from “star selectors”, and error signals derived from the interferometer transfer functions. The star selector positions determine the position of the small aperture within the pickles. The precision is always less than 0.001 arcsec, with an expected accuracy of 0.002 to 0.003 arcsec per observation. Under optimum conditions, the best expected accuracy is 0.0016 arcsec per observation. An observation will consist of the relative positions of several objects in one pickle. Thus the highest accuracy observations will be relative observations within a relatively small field of view.

scholarly journals Photoelectric Polarimetry of the Tail of Comet Ikey-Seki (1965 VIII)

1976 ◽  
Vol 25 (Part1) ◽  
pp. 92-120 ◽  
Author(s):  
J. L. Weinberg ◽  
D. E. Beeson
Keyword(s):  
High Spatial Resolution ◽  
Small Region ◽  
Field Of View ◽  
Large Field ◽  
Small Range ◽  
Comet Tail ◽  
Small Aperture ◽  
Spatial Coverage ◽  
Phase Angles ◽  
Small Field Of View

With few exceptions, measurements of cometary brightness and polarization have been restricted to regions in or near the coma and therefore to a relatively small range of phase angles. Photoelectric techniques are required for detailed wavelength coverage, whereas large-field photographic techniques are better suited for mapping the large regions of sky spanned by a comet tail. Observations with a small field of view provide high spatial resolution but generally restrict multicolor measurements of brightness and polarization to a small region of the comet. Observations with a large field of view (diameter larger than 1 or 2 deg) provide adequate color and spatial coverage but can result in the loss of detail. A compromise is afforded by Fabry photometry, using a modest telescope of small aperture and relatively large field of view.

scholarly journals Hubble Space Telescope Observations of Extragalactic Jets

1996 ◽  
Vol 175 ◽  
pp. 195-200 ◽  
Author(s):  
F. Duccio Macchetto
Keyword(s):  
Hubble Space Telescope ◽  
Space Telescope ◽  
Central Source ◽  
Radio Jets ◽  
Extended Radio ◽  
Extragalactic Jets ◽  
The Subject ◽  
Radio Band ◽  
Better Than

The study of the optical counterparts to the radio jets has been the subject of a number of observing programs with the Hubble Space Telescope (HST). We know that these jets play a fundamental role in transporting energy from the central source to the extended radio lobes. Observations at optical and ultraviolet wavelengths with the HST are essential to obtain spatial resolutions similar to, or better than, those achieved in the radio band and, thus, provide the possibility of directly comparing the sites and mechanisms responsible for the emission at these different wavelengths.

scholarly journals The Gaia spectrophotometric standard stars survey – V. Preliminary flux tables for the calibration of Gaia DR2 and (E)DR3

2021 ◽  
Vol 503 (3) ◽  
pp. 3660-3676
Author(s):  
E Pancino ◽  
N Sanna ◽  
G Altavilla ◽  
S Marinoni ◽  
M Rainer ◽  
...  
Keyword(s):  
Hubble Space Telescope ◽  
Brown Dwarfs ◽  
Space Telescope ◽  
B Stars ◽  
Reference Scale ◽  
Systematic Effects ◽  
M Stars ◽  
Gaia Dr2 ◽  
Stars Survey ◽  
Better Than

ABSTRACT We present the flux tables of the spectrophotometric standard stars (SPSS) used to calibrate in flux the Gaia DR2 and (E)DR3 data releases. The latest SPSS grid version contains 112 stars, whose flux tables agree to better than 1 per cent with the CALSPEC spectra of 11 flux standards for the calibration of the Hubble Space Telescope. The synthetic magnitudes computed on the SPSS spectra also agree to better than 1 per cent with the Landolt magnitudes of 37 stars in common. The typical spreads in both comparisons are of the order of 1 per cent. These uncertainties already meet the initial requirements for the Gaia SPSS project, but further improvements are expected in the next SPSS versions, that will be used to calibrate future Gaia releases. We complement the SPSS flux tables with literature spectra of 60 additional stars that did not pass all the criteria to be SPSS, the Passband Validation Library (PVL). The PVL contains stars of extreme spectral types, such as bright O and B stars and late M stars and brown dwarfs, and was useful to investigate systematic effects in the previous Gaia DR2 release and to minimize them in the EDR3 one. The PVL literature spectra are recalibrated as accurately as possible on to the SPSS reference scale, so that the two sets together can be used in a variety of validation and comparison studies.

Very High Resolution Analysis of the Dynamics of a Coronal Plasmoid

1994 ◽  
Vol 144 ◽  
pp. 593-596
Author(s):  
O. Bouchard ◽  
S. Koutchmy ◽  
L. November ◽  
J.-C. Vial ◽  
J. B. Zirker
Keyword(s):  
High Resolution ◽  
Solar Eclipse ◽  
Total Solar Eclipse ◽  
Field Of View ◽  
Small Field ◽  
High Resolution Analysis ◽  
Ccd Observations ◽  
Resolution Analysis ◽  
Very High ◽  
Small Field Of View

AbstractWe present the results of the analysis of a movie taken over a small field of view in the intermediate corona at a spatial resolution of 0.5“, a temporal resolution of 1 s and a spectral passband of 7 nm. These CCD observations were made at the prime focus of the 3.6 m aperture CFHT telescope during the 1991 total solar eclipse.

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