Star Catalogues

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Some or all of the information on this page is no longer accurate.

It may be relevant to an older version of Stellarium, or it may not be relevant at all. This page itself should be updated, archived or deleted.

This warning has been here since some undetermined moment.

TODO: Describe the difference in locations - user vs. installation directory. Remove obsolete instructions.

In Stellarium version 0.9.0, star catalogues are split into 9 files, which contain stars of varying brightness. These files can be found in the <installation directory>/stars/default/. Only the smaller four of these files come with Stellarium in the main package to keep the size manageable.

About 99% of all these stars come from the NOMAD catalog (Naval Observatory Merged Astrometric Dataset version 1, by USNO). The rest (brighter ones) from Tycho2 and Hipparcos. Please see the stellarium README file for the conditions, under which you may redistribute data files originating from NOMAD.

Here is a list of all available catalogues. The RAM needed column applies for the case of ordinary catalog loading at startup, and is an estimate. (MNG managed to load file 7 with 512 M ram, but only just. YMMV). For mmap loading system memory is not a limit any more, see next section.

File name Star Count Magnitude Range File Size RAM needed Availability 5,013 m < 6.0 138K 256M In default package 21,999 6.0 <= m < 7.5 602K 256M In default package 151,516 7.5 <= m < 9.0 4.1M 256M In default package 434,064 9.0 <= m < 10.5 4.2M 256M In default package 1,725,497 10.5 <= m < 12.0 17M 512M Separate download 7,669,011 12.0 <= m < 13.5 44M 512M Separate download 26,615,233 13.5 <= m < 15.0 153M 512M Separate download 57,826,266 15.0 <= m < 16.5 333M 512M (just!) Separate download 116,923,084 16.5 <= m < 18.0 674M 1024M? Separate download


How to add catalogs

Automatic download

Since version 0.10.1, Stellarium has an automatic download feature built into the program. To use it, press the [F2] key or click on the Configuration button on the left panel. Click on the Tools tab. At the bottom of the dialog, a box called "Star catalog updates" should say "Checking for new star catalogs". After a moment, a button labeled "Get star catalog x of y" should appear. Click on this button to download the first catalog. Once the download completes, the button will appear again if there are more catalogs available. Keep clicking on this button to download all extra catalogs.

Note that you can still manually edit stars.ini, as in previous versions.

Some or all of the information in this section is no longer accurate. It may be relevant to an older version of Stellarium.

This warning has been here since some undetermined moment.

Note: starting stellarium with:

$ stellarium

won't do (the program won't be able to write the downloaded files to their directories).

$ sudo stellarium

should be used instead of the former.

0.9.0 - 0.10.0

To try out the large catalogue files download, and put then in the stars/default sub-directory of the Installation Data Directory.

NOTE: when downloading from this page, do not right-click and save as - left click. These are not direct download links - they are links to the list of download mirrors. Left click on them, and wait for your download to start.

For using I recommend 1GB of RAM, and for at lease 1.5GB. In version 0.9.0 the catalogs are just loaded into RAM, and if you do not have enough of it, swapping will start. Add up the star catalog sizes, compare with your amount of RAM, and your common sense will tell you how many files you can load. Yours, Johannes

Memory-mapped loading

Since version 0.9.1 you can instruct your computer to load all the stars into main memory not at startup, but to load groups of stars when they are displayed for the first time. This is done using the operating systems mmap function, hence the name "mmap loading". Using this technique you can use all of the star catalogs even if you have very little RAM. Also the initial startup time is greatly decreased. The drawback is that your computer loads the stars during normal program operation, when they are used for the first time. Therefore the scrolling and zooming will not be so smooth as when you load all catalogs at startup in advance.


In config.ini, under the [stars] heading, set the key "max_memory" to the maximum amount of memory, in megabytes, to use to load star catalogs directly (the old way). Any catalogs that would push the total memory used over that value will be memory mapped. If unset, the value defaults to 128.

0.9.1 and 0.10.0

For each catalog file that you want to use, you can decide if you want to load it at startup or using mmap by prefixing the catalog name with "mmap:" in stars.ini:

cat_file_name_00       =
cat_file_name_01       =
cat_file_name_02       =
cat_file_name_03       =
cat_file_name_04       =
#you can use mmap loading, if you do not want to load all stars
#immediately into RAM:
cat_file_name_05       =
cat_file_name_06       =
cat_file_name_07       =
cat_file_name_08       =
cat_hip_sp_file_name   =
cat_hip_cids_file_name =

In this example mmap loading is configured for stars_5,...,stars_8 only.

Caveat: when using mmap loading, you must use catalog files that match your computers hardware architecture and the compiler used for building stellarium. The ordinary .cat files can be used with little endian computers and gcc: this applies to all PC (i368 and x86_64 architectures) and the newer Intel macs. Nigel Kerr has made a program for converting .cat files into .bcat files, which can be used with big endian computers and gcc (primarily for the older macs with PPC architecture). All others must use my program ConvertCatToNative.C (in the util directory) for converting .cat (or .bcat) files into a native format appropriate for their architecture and compiler.


Prior to version 0.9.1 the files and were falsely called and Now this misnaming is fixed. The contents of the files is unchanged, just the names have been fixed in order to reflect the contents, which is stars of type 1 and of type 2, respectively. All you have to do is make sure your file stars.ini lists the names of your star catalog files, no matter whether you use the new names or the old ones.

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