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Photometry with adaptive optics: A first guide to expected performance
This paper aims to help prospective observers estimate the likelyperformance of adaptive optics for photometric observations. Both realand simulated adaptive optics data are used in specific examplescovering the major observational situations. These illustrate thedifferent sources of uncertainty: seeing fluctuations, presence of botha large halo and residual fluctuations in the point spread function, andangular anisoplanatism. The astronomical cases studied include isolatedsources, faint structures around a star, and crowded stellar fields. Thephotometric performance image deconvolution is also examined. No attemptis made to investigate exhaustively all possible atmospheric conditionsand observing configurations, but the discussion should be a usefulguide to the feasibility of using adaptive optics in astronomicalprogrammes requiring particular photometric accuracies. Based onobservations obtained at the European Southern Observatory, La Silla,Chile.
| Positional reference stars in the Magellanic Clouds
The equatorial coordinates are determined of 926 stars (mainly ofgalactic origin) in the direction of the Magellanic Clouds at the meanepoch T = 1978.4 with an overall accuracy characterized by the meanvalues of the O-C coordinates, Sa = 0.35 arcsec and Sd = 0.38 arcsec,calculated from the coordinates of the Perth reference stars. Thesevalues are larger than the accuracy expected for primary standard stars.They allow the new positions to be considered as those of reliablesecondary standard stars. The published positions correspond to anunquestionable improvement of the quality of the coordinates provided inthe current catalogs. This study represents an 'astrometric step' in thestarting of a 'Durchmusterung' of the Magellanic Clouds organized by deBoer (1988, 1989).
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Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1978A&AS...33..107J&db_key=AST
| Sir John Herschel's Observations of Stars in the Small Magellanic Cloud
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Osservazione e dati astrometrici
| Costellazione: | Tucano |
| Ascensione retta: | 01h19m42.92s |
| Declinazione: | -71°48'10.0" |
| Magnitudine apparente: | 8.756 |
| Distanza: | 310.559 parsec |
| Moto proprio RA: | -3.8 |
| Moto proprio Dec: | 18.8 |
| B-T magnitude: | 9.937 |
| V-T magnitude: | 8.854 |
Cataloghi e designazioni:
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