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Georges Abell was at the origin of the two main deep sky catalogues which identified objects on the photographic plates of the Mount Palomar T5.

Abell PN

Catalogue of 85 planetary nebulae, many of large size and low brightness, and distant from the galactic plan.

Abell GC

Abell Galaxy Clusters, basic catalogue of galaxy clusters, initially limited to the skies visible from Mount Palomar, then extended to the whole austral sky. It includes over 4,500 clusters..

Astro Koop

Astro Kooperation is and association founded by Stefan Heutz et Wolfgang Ries, two German astro-photographers. Their work is among the best available in deep sky but also in planetary and terrestrial photography.


Edward Emerson Barnard, an American astronomer is at the origin of 300 dark nebulae which carry his name.


Adam Block, an American amateur astronomer. The quality of his pictures is only matched by their quantity.


Generally called surface brightness, which is the luminosity per surface unit usually measured in magnitude/arcsecond².

Capella Observatory

Observatory created by a group of German amateur astronomers, first in Namibia, then on the island of Crete, which made deep sky pictures of exceptional quality.


Christophe Renck, Tof to his friends, member of the Ciel Extrême group, with whom I travelled to Namibia in 2006 and Chili in 2007. He owns a 560 dobson he made himself with which he hunts down planetary nebulae his favourite targets.


Central Spot (bulge for a galaxy)

Austral sky

In this site, austral sky is defined arbitrarily as the part of sky which is hardly visible from European and North American latitudes +/- 35°S.


Is the difference of brightness between two adjacent areas. The minimum level of contrast is that which brings out an object against the background of the sky.


Steve Crouch, amateur Australian astronomer living in the Canberra area. Takes remarkable pictures of the austral sky.

Tandem of galaxies

A tandem means that the two galaxies (or other objects) have been pictured together, but not necessarily that they are physically close to each. The tandem refers to the picture, rather than to the astronomical proximity of the objects.


Ford, Jacoby and Jenner, three astronomers who are at the origin of the study of globular clusters of the galaxy NGC 185.


Robert Gendler, American, amateur astronomer who makes high quality deep sky pictures, especially in terms of colour processing. notamment dans le



High enlargement: means in this site all enlargements equal or superior to +/- 750x and used specifically for the observation of objects, more particularly stars close to Earth.


Arne Henden, American astronomer, specialist of variable stars. Has published numerous stellar fields with magnitudes up to 17V and more.


American astronomer who is at the origin of several catalogues, among others, the nebulae of Magellan Clouds and certain planetary nebulae.


American astronomer at the origin of a catalogue, the HCG, Hickson Compact groups, approximately 100 quartet of galaxies, optically close to each other.


American astronomer at the origin of numerous catalogues, as well as name- giver to the main globular clusters of the galaxies M 110 and NGC 147 and certain regions HII of the NGC 6822 galaxy.

Isolated (galaxy)

Isolated means that the galaxy (or other type of object) has been depicted alone, it doesn’t mean that it is in fact not part of a tandem, trio or a group. The term indicates the illustration rather than the real astronomic position of the object.


Steve Juchnowski, American amateur astronomer. He aims to capture rarely published objects.


Robert Kennicut, astronomer and professor at Cambridge University A participé avec Hodge à la réalisation d’un catalogue de régions HII dans 125 principales galaxies.

Lynd’s catalogues

LDN Lynd’s Dark nebulae, catalogue de plus de 1800 nébuleuses sombres galactiques, de dec > 33°S, jusqu’à 90°N, dont l’opacité est étalonnée dans une échelle de 1, la moins sombre, à 6, la plus opaque.

LBN Lynd’s Bright Nebulae, catalogues de 1125 nébuleuses diffuses galactiques, de dec > 30°S, jusqu’à 90°N.


Ressenti proportionnel au flux de photons reçu par l’œil de l’observateur.


Astronome à l’origine d’un catalogue d’amas stellaires du Petit Nuage de Magellan, analogue du catlogue Shapley – Lyndsey pour le Grand Nuage de Magellan.


Jim Misti, astronome amateur américain. Remaquablement équipé, il réalise de réalise de très belles photos dans son observatoire de Misti Mountain.


Marc Césarini, membre de Ciel Extrême, et grand voyageur devant l’éternel, avec lequel je suis allé en Namibie en 2004, puis au Chili en 2007, et qui me rend régulièrement visite au Petit Telle.


Mathieu Pron, membre de Ciel Extrême, avec lequel je suis allé en Namibie en 2008. Grand amateur de nébuleuse proto-planétaires, d’autant plus qu’elles sont plus difficiles à observer.

Planetary nebulae (dimensions)

Large PN: in this site, arbitrarily, I mean the nebulae larger than +/- 100″, which means those whose surface brightness is weakened by gas expansion.

Small PN: in this site, arbitrarily, I mean the nebulae smaller than +/- 20″, which means those who need considerable enlargement to make their structure visible.


Principal fabricant américain de télescopes dobson de haut de gamme et de grands diamètres


Impurities suspended in the atmosphere, which alterate the brightness of the sky. Light pollution emphasizes these impurities, increases the brightness of the sky and decreases the contrast with the observed objects.


Chris & Dawn Schur, couple of American astro-photographers who operate from the Colorado plateau and its excellent sky.


Saha, Dolphin, Thim, three astronomers at the origin of a photometric catalogue of the Palomar 14 globular stellar cluster.


Romelia Shakhbazian, Armenian astronome arménien, founder of a catalogue of 376 “compact groups of galaxies”, which can be considered as a “super Hickson catalgue” insofar as groups are more dense, compact and the galaxy members weaker.

Shapley – Lyndsay

Harlow Shapley and Eric Lindsey, astronomers who are at the origin of a catalogue of 898 stellar clusters of the Great Cloud of Magellan.


The atmospheric capacity of letting rays of light through while weakening them more or less. Transparence is not connected with light pollution.

Trio de galaxies

Trio signifie que les trois galaxies (ou tout autre type d’objet) ont fait l’objet d’un dessin où elles figurent ensemble, et non pas obligatoirement qu’elles sont physiquement liées. Le mot trio se rapporte ainsi au dessin, et non à situation astronomique des objets.


Atmospheric unrest which has the effect of increasing the blurred effect of the seeing. The necessary enlargement is inversely proportional to the turbulence.

Verontsov – Veliaminov

Two Russian astronomers who published, among other things, a catalogue on interactive galaxies which is considered as the best of its kind.


Internet site with deep sky views realized by DSS, SDSS, IRAS libraries in infrared, GALEX in ultra-violet and RASS3 for X-rays. The whole project is very professional and high quality with numerous additional explanations.