en:documentation:pictures

# Pictures

From the menu: Setup → Pictures
There are two locations to manage the FITS-formatted pictures:

- install directory\data\pictures\sac\ which contain the SAC object pictures.
- user data\pictures\ which is used to store the downloaded pictures from the DSS or the temporary pictures from RealSky.

## DSO Catalog pictures

From the menu: Setup → Pictures → Objects
SkyChart can display deep sky objects in your charts in a more realistic way by showing FITS pictures. This can be independent of the display of symbols for deep sky objects. It can do this in any field of vision.
Before SkyChart can do so, the program needs to categorize all those pictures and load their characteristics into a database. It does this by a scan of the directory were you put those pictures, usually this is the data/pictures sub-directory of your SkyChart installation.

If necessary, you can change the path by entering it directly in the input area, or setting it with a dialog box after clicking the icon.
Please note that you must not specify the directory that contain the fits files itself but the directory just in front. This is because more package for other catalog may be available in separate directory in the future.

When this scan is finished, you will retrieve a message like: There are xxxx catalogued images (9894 in V3 beta 0.1.4).
If it stay with 0 image re-read the paragraph just ahead.

Don't forget to check “Show object pictures on the chart”, at the bottom of the window. Otherwise these pictures will not be displayed on the chart. Also here you can set the Luminosity and Contrast of the images.

If you haven't installed any of those pictures, I can recommend you to install the SAC picture package.

## Background Picture

From the menu: Setup → Pictures → Background
Here you can open a FITS-file to display by entering its file name. After a new installation, the default directory to read from is C:\Documents and Settings\[user]\Local Settings\Application Data\SkyChart\pictures (Windows) or /home/[user]/.skychart/pictures (Linux). In this directory you usually will find the last FITS-file you downloaded from the DSS resources. (named “$temp.fit”). You can change the directory to any other source of FITS-files. For example, if you did install the SAC picture package with a typical installation of SkyChart, you can open FITS images of deep sky objects in your chart from the /usr/share/apps/skychart/pictures/sac (Linux) or C:\Program Files\ciel\pictures\sac (Windows) directory or After opening the file. The active chart will be repositioned according to the settings of the selected picture.
You can set the Visualisation scale, the Luminosity, the Contrast and Transparency of the image and you need to check “Show this picture”.

## DSS RealSky

From the menu: Setup → Pictures → DSS RealSky
SkyChart can display FITS-picures for any place in the chart. This window is meant to configure from which sources to retrieve those pictures. You can get them by Internet, or if you have a RealSky CD-ROM set, from your CD-ROM player

### Online DSS

If you are connected to Internet, you can download FITS-pictures from the Digital Sky Survey (DSS) site. With the combo box you can specify which set of DSS pictures you want to retrieve.
The size of pictures that you request are limited by the field of vision. Usually, you can't retrieve pictures when you set SkyChart to a FOV larger than two degrees of arc. The larger the FOV, the greater chances are that your request times out, or isn't supported by the server at all. You need to realize that it takes a lot of CPU power at the server site to generate a picture, you have to be patient.
To read more about how to download a picture from the DSS, click here.
To read more about the display of these images, click here.
To read more about the configuration of the DSS resources to download those images, press here.

### Download archive

Use this section to archive on your computer the DSS picture you download from the Internet.
You can define here the directory to use for the archive and whether or not you want a confirmation prompt before to archive a file.
See next tab for the options how to display this archived images.

### RealSky

Here you can set the RealSky CD-ROM location for your computer. You have to specify which set of CDs you are using, where the auxiliary files are to be found, the path to your CD reader and where the temporary files can be stored.
You can specify if you want to select a plate from a list. You can also choose to limit the size of the picture.

## Image archive

You can select here how to display the archived images.
Only the images in the FITS format that include the WCS information are eligible for use here. There is many software that allow you to run an astrometric reduction on your images, and also online solutions.

The list can include up to ten directory where the program will search for picture to display on the map.

Select in the first column if you want this directory to be active now.

The second column is the directory itself. Be sure to always include the directory you select for the automatic archive of downloaded DSS images.

The last column indicate the number of pictures actually know in the program database. If you added some images manually in a directory you need to click the “Scan archives” button on top to update the database with the new files.

You can select if you want to show the images on the chart and if you want a label with the image file name.
You can also select the maximum number of images the program will show on a single map. Beware of performance issue if you select a too high value.
You can use the Image list window from a right click on the chart to change this setting for a single map display and also to select other images than the one automatically selected by the program.