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 Installing the CDS software for Windows

Firstly you must install Solarsoft on your PC. Specific instructions for installing Solarsoft on Windows systems are available. 

General users will only need to download the CDS directory within Solarsoft, they will not need the CDS directory in SSWDB. The latter is only required if you intend to use any of the CDS planning software (mk_raster, mk_study, mk_plan).

If you have any problems setting up the software, please contact John Rainnie or Peter Young.

IMPORTANT: starting up IDL

The crucial thing to remember when running the CDS software on Windows is to always type the command

IDL> setssw_windows,/cds

before doing any CDS work. This command sets up most of the important environment variables that allow the CDS software to function correctly.

The sections below explain the steps needed to allow readcdsfits to work on compressed FITS files when running in Windows.

Installing gzip for Windows

CDS fits files are generally stored in compressed format. The IDL routine readcdsfits automatically uncompresses the files by going to the operating system and calling gzip. For UNIX and LINUX, gzip is generally already available but for Windows this is not the case. Thus it is necessary for users to install gzip themselves. (To check if you already have gzip installed, bring up a command prompt and type in "gzip --help". If gzip isn't found, then you don't have gzip installed.)

To obtain gzip for Windows go to Scroll down to the "Executables" section and click on the "self-extract" link for Windows 9x/NT/2000/ME/XP. Once the executable is downloaded, click on it and it will extract gzip to C:\Program Files\GnuWin32.

The next step is to add the \bin sub-directory to your path.

Bring up the Windows Control Panel, click on System , select the Advanced tab, and then click on the Environment Variables button. In the window that pops up look at the User variables. If PATH, path or Path already exists, then select it and click Edit. Append to "Variable value" the following:

;C:\Program Files\GnuWin32\bin

(the semi-colon is important).

If PATH doesn't already exist, then create a new variable called PATH and set the Variable value to be "C:\Program Files\GnuWin32\bin".

Creating a temporary directory

When a CDS fits file is uncompressed by gzip, the uncompressed file is created, read and then deleted. It is best to uncompress the file to a temporary directory. Look in your C: drive, and you may see a folder called "temp" or "tmp". If not, please create a folder called "temp".

To send uncompressed files to this folder, you need to set the CDS_FITS_TEMP_W environment variable. See below.

Creating a personal startup file

Solarsoft for Windows allows you to specify a Personal Startup file for customization. If you open the file:


you should see the following two lines:

rem A personal startup can be defined by editing the following statement

Uncomment the 2nd line (just remove the "rem") and specify the name of a file, e.g.,


Now put the following line in the file:


You can optionally add


if C:\cds_data is the folder where you store the CDS data-files. When set it means that readcdsfits will automatically look in this location for the CDS files.


From the CDS Operations Management Team in the Space Science & Technology Department at CCLRC Rutherford Appleton Laboratory
Site maintained by John Rainnie.
Last revised onThursday ( 2/Aug/2007) at 17:00 .