Emploi de la caméra électronique grand champ avec les très grands télescopes - Extrapolation des résultats obtenus avec le télescope C.F.H.

The large field Lallemand electronographic camera is an ideal receptor for bidimensional photometry with large instruments. With the C.F.H. 3,6 m Telescope, the angular field is 10' at the Cassegrain F/8 focus ; in such a field, there is enough stars in the range 14 < V é 16 to start a decent electrographic sequence ; this sequence extends up to V 21 and permits to measure stars up to V24 25. The linear scale of the plate is large : 1\" 1451,m ; the resolution of the camera is better than 15.:m; even with excellent images 0,6 \", it is possible to analyse correctly the profile of the image of a star or a very distant galaxy. The use of Kodak Electron Image and Kodak Electron Microscope emulsions is adapted to the F/8 focus ; the density recorded on the plate due to the luminance of the sky is : 1 0,5 in B and V band, and 0,12 in U band, for one hour exposure. For detection of very faint objects, 3 to 4 hours exposures are possible in B or V band and more in U. The limiting magnitudes are high : in ultraviolet, we find : U ni= 24,4 for 90 min exposure. As the background emission of the tube is very low, it is possible to use the optical density of the continuous signal due to the luminance of the sky as a in situ criterion of local sensitivity, thus permitting a precise flat field correction. The fact that the transfert function of the camera is the same in every point of the field facilitates the photometric reductions, especially in the case of the gravitational lenses. During two observing runs, excellent plates have been tobtainal of the following types of objects : globular clusters, South arm of Messier 33, elliptical galaxies, N galaxies, quasars, BL Lacertae objects, optical jets, gravitational lenses. The analysis of the plates has started. For the jet of the galaxy Messier 87, observations bring new structures : 1, a luminous filament L close to the nucleus of the galaxy.2, a Taint emission of light between knots D, E and F. 3, condensation H is much larger than the other knots and coincide with the end of the radio jet ; The jet oscillates from its beginning. The jet of the quasar 3C 273 presents condensations and appears also oscillating. The gravitational lens PG 1115 + 080 is variable (6V _ 0,6), with the particularity that the flux ratios of the four known images of the lens remain constant. These examples show the wide possibilities of the large field electronographic camera : this receptor opens anew area for the detections of faint objects, especially in the ultraviolet and for the bidimensional photometry of many types of astronomical objects.

Utilisation Astronomique de la Caméra Electronique Grand Champ,–II

The M87 jet has been observed, in U color, with the C.F.H. telescope and the «large field electronographic camera», by excellent seeing. The signal to noise ratio of the plate is high and three new structures appear: 1, a luminous filament close to the nucleus of the galaxy; 2, a faint emission of light between knots D, E, F and I; 3, condensation H is much larger than the other knots and coincides with the end of the radio jet. Each condensation has a particular shape and, except for H, their dimensions are in the range 30 to 100 pc. The jet appears without break from the nucleus up to H, in agreement with the hypothesis of a continuous ejection of matter from the nucleus. It oscillates from the beginning. At the level of knot A and further, its structure looks complex, in agreement with the radio map of Biretta et al. (1983); a hypothesis relative to the flow of matter in this region is proposed. A precessing jet is a likely explanation of the data at least up to knot I Le jet de M87 a ete observe en U avec le telescope C.F.H. et la camera electronique a grand champ. Les cliches presentent une excellente resolution et un rapport signal bruit eleve. On note trois structures nouvelles: un filament proche du noyau, une emission lumineuse residuelle entre les condensations D, E, F et I; la condensation H est beaucoup plus large que les autres nodosites et correspond a l'extremite radio du jet

Etude, à haute résolution, du jet optique de Messier 87

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Etude, à haute résolution, du jet optique de Messier 87