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CLASS

Using CLASS in Green Bank

On any Linux system in GB running under the bash shell, you can get CLASS started as follows:

export GAG_SYS=linux-intel
export GAG_ROOT=/home/apps/CLASS
export PATH="$GAG_ROOT/$GAG_SYS/bin:"$PATH
class

When you see the "LAS>" prompt, you are in CLASS. You can type help at any time for additional information. Type exit to end your session.

Online Documentation: http://iram.fr/GS/class/class.html

-- JimBraatz - 03 Oct 2003

Scientific Limitations

• CLASS assumes data is calibrated

Technical Limitations

• The CLASS FITS input file name should be all lower case for reasonably simple handling (CFITS doesn't like mixed-case or upper-case names)
• The CLASS FITS file must contain a binary table extension (ie GO FITS files are non-readable)
• Package does not support gzipped files
• It appears that the DATA field must be in the first binary table
• CFITS also gives an error saying that a 16,384-column DATA column is too big, and asks to be recompiled.

Reference Material

• Code for converting UNIPOPS to CLASS format: http://www.tuc.nrao.edu/~sradford/uni2class/

Additional CLASS knowledge

• CLASS is part of the Gildas software package. All Gildas software use the same data format.
• Who uses CLASS? CLASS is used by many astronomers who observe at millimeter bands. It is popular in Europe, and it was taught at an IRAM summer school this year. The IRAM telescopes, the ARO 12m and the SMT, FCRAO, JCMT and APEX all use CLASS, as well as some model makers.
• The Gildas software, which includes CLASS, and GREG, have imaging capabilities that rival IRAF abilities. GUIs can also be constructed, using the SIC language.
• The manual is not always up to date. For the latest info, use the 'help' or 'command' options from within CLASS, or contact the developers.
• CLASS is still being developed. One of the main developers is Robert Lucas, at IRAM in Gernoble, France.
• Supposedly, CLASS is planned as part of the ALMA project as well.
• CLASS FITS vs. CLASS binary
  • As mentioned above, there is a tool for converting UNIPOPS to CLASS format, developed for the old 12m in Tuscon.
  • This same code has been modified to convert Arecibo data to CLASS format as well.
  • Some telescopes convert their FITS files directly to CLASS, but we need to find out more what this means.
  • Using CLASS commands, one can convert one observation in a CLASS binary file to a CLASS FITS file, and this CLASS FITS file can be converted back into CLASS binary.
  • We are investigating wether CLASS can read FITS files with more then one spectrum in them.

GBT Data conversion to CLASS

See the notes on the gbt2class.

-- NicoleRadziwill - 12 Sep 2003