An optimal window for image analysis is determined by means of information theory. The size of the window is then used as a good estimator of image quality. The method is sensitive to the size of the structures present in the image (contrary to the contrast method, widely used to select the best images of a series) and can provide a quality map

From an H-α image of the spiral barred galaxy NGC 3359, an HII region catalogue is composed. The catalogue comprises the position, mean radius and the calibrated H-alpha luminosity of each HII region. The observations of the image of NGC 3359 in H-α were carried out in February 1996, on the Isaac Newton telescope in La Palma in the context of the

We have developed a new diagnostic tool for the study of gamma-ray emission lines from radioactive isotopes (such as 26Al and 60Fe) in conjunction with other multi-wavelength observables of Galactic clusters, associations, and alike objects. Our evolutionary synthesis models are based on the code of \cite{CMH94}, which has been updated to include

We have acquired narrowband imaging of NGC 3587 (the Owl Nebula) in the transitions [O II] λλ3727, 3729, H I λ4861, [O III] λ5007, H I λ6563, [N II] λ6584, [S II] λ6717, and [S II] λ6731. As a result, we are able to evaluate the variation of excitation and electron density over the projected envelope of the source. We propose that the Owl Nebula

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As a parallel result from a project aimed at determining accurate distances to more than 30 Planetary Nebulae using the extinction-distance method, we report here the serendipitous discovery of a giant halo around NGC 7027. We obtained the spectra of more than 50 field stars around each PN with the LDSS2 multi-slit spectrograph in the 4.2m