The JCMT is preparing to adopt AIPS++ for spectral line data reduction. The software is well suited to handling data from existing JCMT receivers and will enable sophisticated handling of spectral line data cubes from HARP/ACSIS. As a consequence, it is expected that support for SPECX by JCMT staff will eventually be discontinued. AIPS++ is available for Linux (on Intel based machines) and Solaris (on SPARC-based workstations). AIPS++ features include:

• A fully featured scripting language called glish. This features a C-like syntax together with powerful capabilities for manipulating data in arrays and tables (similar to IDL). Glish will enable greater automation of data reduction tasks than is currently possible using SPECX macros.
• A single-dish specific data reduction and visualisation tool known as DISH. This enables tasks such as co-adding spectra and baseline fitting to be performed either via a GUI or via the glish command line.
• Advanced image handling capabilities via the image tool. The image tool incorporates features such as visualisation, mask handling, source profile fitting and statistical analysis.
• Tk and PGPLOT bindings for glish, allowing the user to build custom GUIs and rapidly produce publication quality graphics from data. AIPS++ thus possesses the flexibility to be successfully used for a wide variety astronomical visualisation and analysis.

AIPS++ lies at the heart of the data reduction system for ACSIS. The generation of spectra from the raw autocorrelation lags is achieved by the use of parallel, distributed reduction tasks (written in C++) co-ordinated by the glish scripting and messaging system. It is envisaged that the raw spectra will be saved to disk as AIPS++ measurement sets, while gridder tasks will produce FITS format data cube slices. It is anticipated that JCMT users will then use AIPS++ for further analysis and reduction of their data from the ACSIS backend.

The DISH Plotter window.

The native AIPS++ data format describing observations is the Measurement Set (MS). At present, such measurement sets can be constructed from existing GSD format data files from the JCMT using a GSDfiller program. Glish equivalents of the SPECX dasmerge function have been developed, enabling the straightforward reduction and visualisation of JCMT data from the current DAS backend.

The training of support scientists in the reduction of JCMT data with AIPS++/DISH will begin in the autumn of 2003. Regular users of JCMT spectral line instruments will then be encouraged to try AIPS++ and DISH for themselves, ahead of the commissioning of ACSIS on the JCMT. Data from ACSIS will be reduced using AIPS++, in conjunction with the provision of an ORAC-DR data reduction pipeline for quick-look data reduction and visualisation at the summit.

Further information can be found at:

• The AIPS++ homepage
• The ACSIS homepage
• The HARP homepage

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