With Cartes du Ciel-SkyChart it is easy to install popular ready-to-use catalogs. You can download and use them for free. Most catalogs aren't larger than some tens of megabytes, these will be helpfull to many dedicated amateurs.

But maybe you want to push things a little further. For example, you want your charts to display stars to a magnitude of 19. Then you need to download the USNO-A2.0 catalog. Before you start downloading, consider its size. Installed, this catalog will consume 6.11 GB. Still interested? See The large catalogs

You also can choose to build your own catalog. As a basis you can choose from thousands of existing catalogs and modify them for usage in Cartes du Ciel-SkyChart. You also can gather information in your own ASCII-file. To use these kinds of catalogs, you need the tool CatGen to adapt them for Cartes du Ciel-SkyChart. Those catalogs demand a little more time before you can use them in Cartes du Ciel-SkyChart. But this is a chapter about the ready-to-use catalogs, so lets continue with that:

To get to the source of those catalogs you go to the download link from the Cartes du Ciel-SkyChart homepage.

When you want to install these catalogs for all users, you need to have Administrator (Windows) or root (Linux) rights. If you don't have these, you can choose to install the catalogs somewhere in your computer where you have sufficient rights. (For example, your home directory.)
Download the catalog files that you want, save them (temporary) somewhere on your computer. Use your favorite unzip-program to decompress the files to the installation directory of Cartes du Ciel-SkyChart. With Windows this is typically something like C:\Program Files\Ciel, with Linux ususally this is /usr/share/skychart. But you can choose another path. Remember to configure the path to your catalog with Setup → Catalog.

You can activate or deactivate your catalogs with the dialog boxes from Setup → Catalog. Click the appropriate tab for your specific catalog.
Some catalog are moved to the Obsolete tab as they are replaced by more recent data. So also look here if you not find them.

Most of this catalog are now obsolete and replaced by GAIA DR2.
For a new installation look for GAIA DR2 above.
But you can still refer to this documentation if you already own one of this old catalog or if you have a specific reason to use them.

HST-GSC is an acronym for “Hubble Space Telescope Guide Star Catalogue”. The original goal was to keep the HST properly pointed at its target. This catalog contains over 19 million objects brighter then magnitude 16, of which 15 million were identified as stars. This catalog is considered obsolete. Only to be complete, I 'll describe how to retrieve this catalog. I recommend you to use the HST GSC Compact.

This large catalog is available from ftp://adc.gsfc.nasa.gov/pub/adc/superseded/1/1220/GSC/. After you have done everything that is needed to use this catalog, you will discover that this catalog consumes 1.18 GB of space. The .gsc files in this version contain ASCII data.

In the directory of the ftp-server you find directories and 'tarball' files with names like LFFF.tar.gz. (Yes, there is also a file with the name N0730.tar.) To download this catalog, you can choose to do it in a fast way or a slow way.
The fast way: download all tarball files to your computer, including the N0730.tar. To correct this small error, rename N0730.tar to N0730.tar.gz.
Next step is to 'untar' all tarballs with your favorite archive (unzip) program. (With Windows, I use ZipGenius. Every Linux distribution knows how to deal with tarballs.) Usually, the content of the tarball will be written in a directory with the same name as the tarball with omission of the '.tar.gz' part. In this directory you use your favorite archive program again to decompress every file with the .gz extension.

Watch this: After the untar action, pretty often the contents of the tarballs (i.e. N0000.tar.gz) ends up in a directory export\pub\ftp\pub\adc\archives\superseded\1\1220\GSC\LFFFF, and pretty often they don't. Whatever the result, after decompression move all 'LFFFF' directories with their content to one common directory. After that, set Cartes du Ciel-SkyChart to use the common path with the Setup → Catalog → CDC Stars dialog box.

Downloading the tarball is quite fast, the decompression of all the .gz files however isn't. (It's well possible that it will take you a few hours to do them all.) In any case, this is the fast way. The slow way would be to download every single .gz file from every subdirectory of the FTP-server. And then you still need to decompress them..

From the Cartes du Ciel-SkyChart point of view there is not much difference between the HST-GSC original FITS and the HST GSC Compact. Again, it's based on the data of 19 million objects brighter than magnitude 16, of which 15 million are identified as stars. The size of the HST GSC Compact makes all the difference: on your harddisk it only needs 290 MB. This is because the .gsc files in this catalog are in a binary format.
The original Cartes du Ciel-SkyChart version 2.7x allready could work with the version 1.1. Now, this catalog is considered obsolete. The version 1.2 version became its successor (also obsolete now), at this moment we recommend you the HST-ACT version to serve as your HST GSC Compact catalog. You can download this one from

• ftp://cdsarc.u-strasbg.fr/pub/cats/I/255/GSC_ACT/, or from
  
• ftp://adc.astro.umd.edu/pub/adc/archives/catalogs/1/1255/GSC_ACT/.
  

When your only possibility is to use HTTP, you might consider downloading from

• http://cdsarc.u-strasbg.fr/ftp/cats/i/255/GSC_ACT/.
  

From your download source, copy all files to a local directory. If you still have got the older HST GSC compact versions 1.1 en 1.2, you still can use them with Cartes du Ciel-SkyChart.

Last but not least: Activate your catalog with the Setup → Catalog → CDC Stars dialog box.

As I said earlier, this is a large catalog. It contains data of 526,280,881 stars, among the data are the magnitudes in V and B. The limiting magnitude is at 19+. Unfortunatly, this catalog doesn't contain data about the proper motion.

There are some versions of the 'USNO A' catalogs, the most recent is USNO A version 2.0. There is also a smaller subset from the 'USNO A' catalog. This summary is considerable smaller and is called USNO-SA 2.0, but it is useless to plot a chart.

And then there is the USNO B version. Since the arrival of this catalog, the professionals consider USNO A2.0 as obsolete. USNO B contains data of 1 billion objects, complete with data about their proper motions. See the next paragraph.

The installed catalog will occupy 6,11 GB on your media.
The 'USNO A' catalog is no more available from NOFS so I put a copy for you on my own web server.
To download the USNO-A2.0 catalog, use the following link to copy everything from

• https://vega.ap-i.net/pub/usnoa/
  

Wherever you retrieve your USNO-A catalog from, make sure that (after eventually decompression) your catalog contains files with a .acc and .cat extensions. Files from ftp://cdsarc.u-strasbg.fr/pub/cats/I/252/USNO_A2 contain files with a .ppm extension. I didn't get these to work with Cartes du Ciel-SkyChart, save yourself from this dissapointment.

Copy files one by one. If you don't do that, you 'll risk that your process will be killed at the server site, simply because your task allocated to much memory. (These files are large, remember?) After downloading, put all the files together in one directory if you didn't do that allready.

And again: Activate your catalog with the Setup → Catalog → CDC Stars dialog box

Since the version 3.9 Skychart can use the USNO-B1.0 catalog in U.S. Naval Observatory format, 180 directory 000 to 179, each with 10 .acc and 10 .cat files, 78 GB total size.

You can download this catalog using Bittorent, download size is 46 GB:

• Get the torrent file
• Open the torrent file in your bittorrent client software. You can eventually select only the zone directory you want. Each zip file contain the catalog data for a one degree declination zone, the name of the file is the South Polar Distance (DEC+90) of the zone.
• When the download is complete unzip each of the 180 zip files to recreate the original catalog structure.
• Please keep seeding to help other to get the data!

The configuration setting is in the Catalog → Obsolete tab for two reason: to not bore the many people that cannot get this files, but also because I really think that NOMAD or PPMXL is a real improvement over this catalog.

The Naval Observatory Merged Astrometric Dataset (NOMAD) contains astrometric and photometric data for over 1 billion stars derived from the Hipparcos , Tycho-2 , UCAC2 , and USNO-B1.0 catalogs for astrometry and optical photometry, supplemented by 2MASS near-infrared photometry.

See on this page the NOMAD installation detail with Skychart. The data itself need to be downloaded using Bittorrent.

The PPMXL catalog of positions and proper motions on the ICRS. Combining USNO-B1.0 and the two Micron All Sky Survey (2MASS).
It contain about 900 million stars, is complete down to magnitude 20 and include the proper motion for every object.

See on this page the PPMXL installation detail with Skychart. The full data is easily to download from the CDS.