The NOMAD catalog

 - a new catalog of stars for Skychart (Carte du Ciel)

From the skychart site:
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.

Thank to the effort of Oleg Maliy we can now use this catalog with Cartes du Ciel!

The catalog is available to download by Bittorrent. It is presented in the form of text file for each zone area (South Polar Distance).
You need to run Catgen to use this data with Skychart but this as the advantage to let you select the data you need for the catalog size you want.
This also make it easy to use this data outside of Skychart.

For each star the files contain:

  • NOMAD identifiers.
  • A flag for each source catalog.
  • Coordinates ICRS, with mean error and source flag.
  • Mean epoch of the position.
  • Proper motion, with mean error.
  • Magnitude B, V, R with indication of origin.
  • Magnitude J, H, K from 2MASS
  • A flag if the star is a recommended astrometric standard.


Build a catalog for Skychart

Warning An error was found on the first version of the file nomad.prj available before December 20 2011. Be careful to only use the file nomad2.prj available in the following zip file.

  1. Get the zip file containing the torrent and a sample Catgen project.
  2. Download all the torrent, or just the declination zone you need. In this last case beware the zone number are South Polar distance.
  3. Extract every .rar file. (Use 7zip or on Linux: ls -1 *.rar | xargs -n1 unrar e )
  4. Copy every .txt file to a single directory.
  5. This result in a directory with 1800 .txt files for a total size of 152G.
  6. On Linux/Mac set „ulimit -S -n 20000” see Catgen documentation
  7. Launch Skychart
  8. Setup / Catalog / Catgen
  9. Load the sample project: Load Project → nomad2.prj
  10. Update the input files with your location folder: Input catalog files, click the folder button → select the 1800 .txt files (be patient until it update the list)
  11. Click the Next button.
  12. On General option page click the Next button.
  13. Review the field list. You can add or remove information here. Click the Next button.
  14. Output directory → select where to put the catalog.
  15. Click the „Build catalog” button.
  16. Wait a few hours … (three hours for me). Using the default options the result is 48GB in size.
  17. You can now add the catalog to Skychart.



And a final note: Please let the torrents active after you finish to download! We need your upload capacity to make the files available to all on the best condition.

Above is all the information on how to adapt the Nomad catalog for your copy of Carte du Ciel.  It looks like (and is) a lot of work.  My experience in getting this catalog.
Bittorrent download of 250 GB
3+ 24 hour days computer time
Extract .rar files (18 directories to 180 directories)
1 hour
Copy 10 files each from 180 directories to single directory
4 hours
Run Catgen to produce the final catalog (on my computer)
8 hours
Once you have done all this, you have your compressed Nomad catalog in a series of directories under the Nomad directory (about 56 GB) ready to install.
Windows Final Installation:
Copy Nomad and all of its subdirectories to /Program Files/ciel/cat/  This puts this catalog in the same subdirectory as all of the other catalogs.
Open Cartes du Ciel.
Goto Setup>Catalog
On the first menu (Catalog tab), click Add
A menu of the "cat" directory comes up.  click on Nomad
Go down to the bottom of the directories and click on the file nmd.hdr
The new catalog nmd will appear on the Catalog page with a red box next to it.  Click on the box and it will turn green.  The default setting has the catalog only used on the 4 most zoomed in settings (0,1,2,3). If you try higher setting there are too many stars to display on the screen.
Click Apply, then OK to leave the set up. 
Be sure that before you leave the program, you save the configuration or you will have to repeat the installation. 

5-10 minutes.
While the data is freely available to you, getting it is quite the time waster.    I am therefore making my compiled copy available to those who would like to get a copy.  Since copying 56 GB to a usb drive is time consuming I am charging a $20 fee to do this.   I am providing two options to accomplish this.

Option 1.  You send me a hard drive capable of holding 60GB or more, formatted in NTSF (windows) format, and no larger than a 3.5" drive.  I will place a copy of the Catgen generated Nomad catalog on it and send it back.   This will cost you $26 which includes US shipping.  If you ship me some old huge heavy drive, I will request more shipping money. 

Option 1

Option 2.  I have access to 2.5" IDE harddrives in the 60-100GB size.  These are used and working drives and will be set up to run off your USB 2.0 port.  NO Guarantee on what capacity drive you will get, but it will be in the 60-100GB range, and have the Catgen generated Nomad catalog on it.  The Drive is yours to keep.  Since the data can be legally copied, several people can go together to get one of these for their use.  This option costs $50 including US shipping. 
Option 2


If you are interested in using the data with a different program, I still have the original downloaded uncompressed data.  It is about 250 GB in size.  For that reason it would require a larger more expensive hard drive and more of my time to copy.  If you are interested in receiving the data in this format contact me at johnduchek@duchekconsult.com and we will see what we can work out.