Downloads of C2A Software, Catalogues and Tools

Distributions

Orbital Elements

The file com_obs.c2a contains a list of observable comets (obtained from the Minor Planet Center site). The URL that can be used directly within C2A is:
http://www.astrosurf.com/c2a/orbel/com_obs.c2a

The file ast_500.c2a contains orbital elements for the 500 first asteroids (obtained from the site of the Bowell Catalogue). The URL that can be used directly within C2A is:
http://www.astrosurf.com/c2a/orbel/ast_500.c2a

The file ast_1000.c2a contains orbital elements for the 1000 first asteroids (obtained from the site of the Bowell Catalogue). The URL that can be used directly within C2A is:
http://www.astrosurf.com/c2a/orbel/ast_1000.c2a

The file ast_2000.c2a contains orbital elements for the 2000 first asteroids (obtained from the site of the Bowell Catalogue). The URL that can be used directly within C2A is:
http://www.astrosurf.com/c2a/orbel/ast_2000.c2a

The file ast_crit.c2a contains orbital elements for the critical asteroids (obtained from the Minor Planet Center site). The URL that can be used directly within C2A is:
http://www.astrosurf.com/c2a/orbel/ast_crit.c2a

The file ast_nea.c2a contains orbital elements for peculiar asteroids such as the "Near Earth Asteroids" (obtained from Minor Planet Center). The URL that can be used directly within C2A is:
http://www.astrosurf.com/c2a/orbel/ast_nea.c2a

The file ast_dist.c2a ontains orbital elements for distant asteroids (obtained from the Minor Planet Center). The URL that can be used directly within C2A is:
http://www.astrosurf.com/c2a/orbel/ast_dist.c2a

Catalogues

This ZIP file contains the Tycho-2 catalogue in the C2A format and must be decompressed to be used by the program. This version includes the two supplement catalogues. It also corrects a problem with the stars from the supplement catalogue (found on the 1st of May 2007).

This ZIP archive contains the Guide Star 1.1 catalogue in its compiled format for C2A. The files in the ZIP file must be uncompressed into a folder (named GSC for instance) preserving the sub-directory structure. This version of the catalogue is provided for historic reasons, but it is advised to use instead the version 1.2 of the Guide Star catalogue (see below).

This ZIP archive contains the Guide Star 1.2 catalogue in its native format. The files in the ZIP file must be uncompressed into a folder (named GSC for instance) preserving the sub-directory structure. It is advised to use this version of the Guide Star catalogue. It allows in particular to perform searches on the object names.

All the BT-Atlas images are available in this ZIP archive in the PIC format (the format from the well known Iris image processing software) with all their dynamic. The files in the ZIP file must be uncompressed into a folder (named BT-Atlas for instance) preserving the sub-directory structure. The author wants to thank Christian Buil for having given free access to this great image catalogue.

Text catalogue example in the C2A format.

Compilers

User Catalogue Compiler

Version 1.1.0
(Windows 7 64 bits compatible)

Text user catalogues are useful when catalogues are not too big. However, for large catalogues, loading time within C2A et screen refresh become prohibitives.

C2A offers the possibility to compile an object catalogue. This means that a binary file can be produced from an ASCII file whose syntax is described by the user. This binary file can then be loaded and displayed much faster within C2A. Furthermore, users have the ability to define their own fields whose value is displayed when objects are identified within the maps.

For a text database to be compiled, the user has to provide a certain number of information in a text file called a "model file". This information will allow the database compiler to figure out which data is to be extracted from the ASCII file and used to produce the compiled file.

The database compiler for C2A is called DC and must be launched from the Windows Command Line. In order to install the compiler and use it, first download the file DC.zip using the link on the left, uncompress it, and copy the executable file DC.EXE in a directory of your choice. Then open a Windows command line (go into the Start menu, choose Execute..., then type cmd followed by OK). Go then into the directory where the DC compiler has been installed. Here, the compiler can be used using the directions provided in this short Compiler User Guide (in English).

Note: The old DOS version 1.0.18 of the User Catalogue Compiler (which does not work on Windows 7 64 bits) is also available here.

Compiler for the UCAC1 Catalogue

Version 1.1.0
(Windows 7 64 bits compatible)

The UCAC1 catalogue is published by the US Naval Observatory under the form of a CD-ROM that contains a file called u1.tar.gz. In order to be efficiently used by C2A, this catalogue must be compiled first. To compile the UCAC1 catalogue, simply go through the following process:

• Download first the file UCAC1.zip from the link on the left, uncompress it and copy the file UCAC1.EXE in a directory on a disk with at least 6 gigabytes of free space.
• Insert the UCAC1 CD-ROM in your CD-ROM drive.
• Copy the compressed file u1.tar.gz in a directory of your hard disk drive.
• Uncompress the file u1.tar using for instance the Winzip utility.
• Extract all the files contained in the TAR file u1.tar. The Winzip utility is also able to perform this extraction. At this step, you should have 169 files from z001 to z169 that take 1.73 gigabytes on your disk (do not forget to delete these files after the compilation process!). Note that the extraction process of the TAR file can take some time and that you need plenty of free space on the disk used by Winzip to store temporary file.
• Open a DOS Command window (for instance by going into the Start menu, then Run... and typing CMD - this is valid for Windows XP) then go into the directory where you have copied the file UCAC1.EXE (where the compiled catalogue will be created).
• Run the command UCAC1 "Access Path to UCAC1 files" "Compiled Catalogue Name" where "Access Path to UCAC1 files" is the access path to the directory where are located the files z001 to z169 and "Compiled Catalogue Name" is the name of the file that will contain the compiled catalogue. This command can be for instance:
  UCAC1 D:\TMP D:\UCAC1.DAT.
• During the compilation process, 48 temporary files are created then automatically deleted after the compilation is complete. If the compilation process is stopped, all these files must be manually deleted. 27,425,433 objects must be reported by the tool.

The compilation process takes around 30 minutes on Core i5 computer (or 2 hours and 3 minutes on a Pentium III computer at 1 GHz...). The output file (for instance UCAC1.DAT) has a size of roughly 889 megabytes. Store it in a directory of your hard disk drive then specify the access path within C2A by going into the tab Paths of the Options dialog box (accessible from the menu Tools/Options...). This access path could be for instance "D:\UCAC1\UCAC1.DAT" assuming that a directory "UCAC1" has been created directly on the C: drive root. The compiled file must be exactly 932,468,278 bytes

C2A is now ready to read the UCAC1 catalogue!

Note: The old DOS version 1.0.0 of the UCAC1 compiler (which does not work on Windows 7 64 bits) is also available here.

Compiler for the UCAC2 Catalogue

Version 1.3.0
(Windows 7 64 bits compatible)

The UCAC2 catalogue is published by the US Naval Observatory under the form of 3 CD-ROMs that contain 288 files named from Z001 to Z288 as well as 36 files for the Bright Star Supplement names s01 to s36. In order to be efficiently used by C2A, this catalogue must be compiled first. To compile the UCAC2 catalogue, simply go through the following process:

• Download first the file UCAC2.zip from the link on the left, uncompress it and copy the file UCAC2.EXE in a directory on a disk with at least 10 gigabytes of free space.
• Copy the files Z001 to Z288 and s01 to s36 in a directory of your hard disk drive (if you do not have the Bright Star Supplement files s01 to s36 on the UCAC2 CD-ROMs, you can download them from the Miscellaneous section in this page).
• Open a DOS Command window (for instance by going into the Start menu, then Run... and typing CMD - this is valid for Windows XP) then go into the directory where you have copied the file UCAC2.EXE (where the compiled catalogue will be created).
• Run the command UCAC2 "Access Path to UCAC2 files" where "Access Path to UCAC2 files" is the access path to the directory where are located the files z001 to z288 and s1 to s36. This command can be for instance:
  UCAC2 D:\TMP
• During the compilation process, 48 temporary files are created then automatically deleted after the compilation is complete. If the compilation process is stopped, all these files must be manually deleted. 48,330,571 objects must be reported by the tool.

The 24 output files (UCAC2_00.DAT to UCAC2_23.DAT) have a size of roughly 2.17 gigabytes. Store them in a directory of your hard disk drive then specify the access path within C2A by going into the tab Paths of the Options dialog box (accessible from the menu Tools/Options...). This access path could be for instance "D:\UCAC2" assuming that a directory "UCAC2" has been created directly on the C: drive root.

The compilation process takes around 1 hour and 30 minutes on Core i5 computer. Once the compilation process is complete, the source files (Z001 to Z288 and s01 to s36) can be deleted from the hard disk.

Note: The old DOS version 1.2.0 of the UCAC2 compiler (which does not work on Windows 7 64 bits) is also available here.

Miscellaneous

Polynomial File wap.b98
November 6, 2006

This file cover the period 1900 to 2100 for the planetary position calculation. It must be uncompressed and must overwrite the file wap.b98 in the C2A installation directory (by default C:\Program Files\C2A).
Download size is 11.5 MB

Polynomial File wap.b98
October 16, 2016

This file cover the period 1500 to 2100 for the planetary position calculation. It must be uncompressed and must overwrite the file wap.b98 in the C2A installation directory (by default C:\Program Files\C2A).
Download size is 34.5 MB

Occult Watcher Add-in
Version 1.6
November 21, 2011

Occult Watcher is a software designed to easily manage predictions of star occultation by asteroids. An Add-in is available to directly launch C2A from Occult Watcher and display a map of the occultation event (setting automatically the time, location and catalogue for the considered event). The Hipparcos, UCAC2, UCAC3 and NOMAD catalogues are often used in occultation predictions, so it is necessary to have them installed on your computer before using this Add-in.

Take care that in order to use this C2A Add-in for Occult Watcher, you need at least version 2.0.43 of C2A and the most recent version of Occult Watcher.

To install the Add-in, simply extract the file OccultWatcher.C2a.dll (available in the ZIP file) and copy it into the Occult Watcher installation folder. A C2A entry will then be added in the Occult Watcher Add-in menu. To launch C2A and get the map of an event, select this event in the Occult Watcher list and go into the Add-in menu to create the C2A Occultation Map.

New features in version 1.6 are the following:

• A new option has been added in order to request C2A to automatically load the orbital elements of the asteroid involved in the occultation event. These orbital elements are obtained from a local Astorb.dat file that must be available on the local disk and declared in C2A using the Solar System advanced options in the Options dialogue box.

Bright Star Supplement
December 3, 2006

The catalogue UCAC2 uses 36 files (s01 to s36) containing information on bright stars which must be integrated into the compiled UCAC2 catalogue for C2A. These files are not provided on all UCAC2 distributions. Therefore, they are provided here for download.
Download size is 13.3 MB

C2A DOS Version 4.1.4
September 2002

C2A is available in a DOS version which is compatible with all the Windows Operating Systems as well as in a DOSBox emulation which also runs on Mac OS. The advantage is that it can be used on hardware platforms that maybe not be powerful enough to run recent versions of Windows. This tool is therefore perfect to run a simple Planetarium program on an old machine close to the telescope.

By default, C2A for DOS is able to read three star databases (around 2100, 9000 and 260.000 objects) as well as three deep sky objects databases (around 110, 5000 and 8000 objects). All these catalogues are provided with the software. C2A for DOS is able to read the BT-Atlas catalogue (6600 objects) with its 4649 associated images. It is also possible to access the Guide Star catalogue (10 millions objects) as well as the USNO catalogues in different versions (USNO-SA1.0, USNO-A2.0). These large catalogues are not provided with the C2A for DOS distribution.

To install C2A for DOS, download first the file C2AD_414.zip with the link on the left, uncompress it in a temporary directory and run the executable INSTDOS.EXE. Then, simply follow the steps as displayed on the screen. At the end of the installation process, you can delete the files in the temporary directory.

All the documentation about C2A for DOS is available in a file called C2A.PDF provided in the ZIP archive. Take care that this documentation is in French only! Sorry about that, but it would be a tremendous work to translate it...

C2A DOS Version 4.1.5
January 2010

This is a DOS version of C2A which supports the polynomial file SLP96 from the IMCCE in order to compute planetary positions over the period 1987 - 2020. Version 4.1.4 only supports the period 1987 - 2009.

In order to install this version, install first version 4.1.4 above (if it is not already installed on your computer) then overwrite the files C2A.EXE, C2A.MSG and C2A.B98 with those from the ZIP archive file.

Last Update : 2023-04-03
Author : Philippe Deverchère