F.A.Q.
What does “deep sky” mean?
In astronomy, deep sky objects are nocturnal elements, which do not belong to the solar system (planets, comets, asteroids), simple and complex stars.
Generally, these objects are not visible to the naked eye, but the shiniest of them can be seen with a small telescope or even with a good pair of binoculars.
These objects are the following:
- Stellar clusters
- Open clusters
- Globular clusters
- Nebulae
- Diffuse nebulae
- Emission nebulae
- Reflection nebulae
- Planetary nebulae
- Dark nebulae
- Galaxies
- Quasars
Source : Wikipedia (http://fr.wikipedia.org/wiki/Ciel_profond)
How to download a picture or a photograph ?
It is very easy to download a picture or a photograph from my site onto your hard drive. Click on the page you want. You can access the object either through the thumbnails, or the search function by type, alphabetical order or recency.
Each page of an object includes:
– the caption of the photograph of the field corresponsing to the sketch, the caption of the sketch itself and an observation report.
1) Choose the caption of the photo or the picture you are interested in saving. Right-click the caption of the image and, in the new window, select “open link in new window”.
2) The picture appears in a new window, screen size. If you run the mouse over the new picture, the arrow changes into a magnifying glass with a “+” sign on the glass. If you left-click the picture with the magnifying glass, it will increase to its real size, much larger than the screen size.
3) Right-click the real sized picture, and in the drop down menu which appears, select “save as”. Now you just need to choose the folder and save the real-sized picture.
(NB: back to step 1) If you have left-clicked the picture caption, rather than right-clicking, you will have a new window with an animated picture comparing the photo and the picture and vice versa if you left-click on the object. Right-click the photo and the sketch appears, left-click the picture and the photo comes up.
Mai 18 2009
What does C(xxx) / S(yyy) mean in observation reports?
To indicate colours, I use the Paint Shop Pro software scale. Each colour and saturation is represented by a number, between 0 and 255. This scale is common to most design software.
For example, C130 / S 60 corresponds to a bright blue colour and a high level of saturation, frequently a characteristic of coloured planetary nebulae.
In an astrological sketch, what should dominate, stars or galaxies?
An observer who had recently discovered my picture of M 106 with a T 635mm made the following remark:
“I like stars to have “shaky” contours, to appear fragile, when they are pencil-drawn it is possible. In a photograph they appear to be overbearing, if I may say so and tend to crush the rest of the picture “ Don’t believe that this remark disappointed me, on the contrary, I find it very interesting. The question is important, especially for beginning sketchers: should there be a relationship between the importance of different represented objects in an astronomical sketch? Of course the question is valid for galaxies, planetary nebulae, diffuse, or dark and so on…. I will not pretend to have the answer here, but an opinion, nevertheless. The main question is to determine the photographer’s aim: does he want an artistic picture, or a “sketched photograph”. Is it aesthetics or exactitude, which should be privileged? As far as I’m concerned, my answer is unambiguous and I shall stick to it: my goal is to draw what I see, everything I see, and nothing but what I see.
Under these conditions, the answer to the first question “what should dominate” can only be …. the sky! If in the field of vision the stars are numerous and bright, they will dominate the picture, if the nebulae or the galaxy is bright in a dull field, it will be the opposite.
Among my pictures there are numerous examples which illustrate the concept: compare two very dull objects, HCG 56 and 78 and two bright objects NGC 4088 and 4217. For each pair, one object is in a very dull field and the other against a very bright background. I don’t judge which of the pictures is better, I will let you decide, for me the most important question: “does my picture represent what I have observed? If my answer is “yes”, I’m satisfied, if it isn’t, the conclusion is “here’s an object I need to re-observe and draw again”
October 8th 2008