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GBTIDL Release Notes Version 2.3

• Introduction
• Getting Started
• New Features
• Bugs Fixed
• Register as a GBTIDL user
• Running GBTIDL in Green Bank, Socorro, or Charlottesville:
• Running your own copy of GBTIDL
  • IDL License
  • Download and Installation of GBTIDL

Introduction

We are pleased to announce the release of GBTIDL, version 2.3. GBTIDL is an interactive package for reduction and analysis of spectral line data taken with the Robert C. Byrd Green Bank Telescope. The package consists of a set of straightforward yet flexible calibration, averaging, and analysis procedures (the "GUIDE layer") modeled after the UniPOPS and CLASS data reduction philosophies, a customized plotter with many built-in visualization features, and Data I/O and toolbox functionality that can be used for more advanced tasks. The entire package is written in IDL.

As of 10:45 AM EST on Wednesday, November 14, 2007, gbtidl at all NRAO sites corresponds to version 2.3 and includes the changes described in this note.

GBTIDL version 2.3 containes a few new features and one bug fix, as described in these release notes.

Users may wish to also read the release notes of the latest version of sdfits which includes changes of interest to GBTIDL users.

Getting Started

• The starting point for GBTIDL documentation, bug reporting and tracking, and discussion is here: http://gbtidl.nrao.edu/
• A comprehensive User's Guide is available.

New Features

• New SUBREF_STATE field in all data containers. This field is used when subreflector noding is occuring during a scan (SUBMOTIN keyword in the GO FITS files is equal to "SubNod"). It has a value of 1 when the subreflector is at the first position during that integration, a value of -1 when it is at the second position during that integration, and 0 when it is moving at any point during that integration. This field is copied from the appropriate SUBREF_STATE column in the FITS file when present. IDL calibration routines are being developed to exploit this value but are not included in this release. When there is no SUBREF_STATE column, the value of the SUBREF_STATE field in the data container is 1. For continuum data this field is an IDL pointer variable that points to an array of integers, one integer for each data point (integration) found in that data container.
• New SUBREF index field. This field can be used in data selection just like all other index fields. This is a copy of the SUBREF_STATE value for the row pointed to by that index entry. There is no SUBREF index field for continuum data because a continuum data container contains data from all integrations in one scan and hence there is no single SUBREF_STATE value for that data container (row in the index file).
• The index version number has been changed because of the previous new feature. GBTIDL will automatically update older index files as needed.

Bugs Fixed

• The speed when reading Zpectrometer SDFITS files was substantially improved.
• Negative Gaussian fits were not being display by fitgauss and gshow. The fit was successful but it was not displayed and it was accompanied by several errors. This bug has been fixed.

Register as a GBTIDL user

• Use the on-line registration form.

Running GBTIDL in Green Bank, Socorro, or Charlottesville:

• At the unix prompt, simply type 'gbtidl'

Running your own copy of GBTIDL

IDL License

• You must have an IDL license to run GBTIDL. IDL version 6.0 and later is supported. If you don't have a license you can run GBTIDL remotely, using the computers in CV or GB. See the GBTIDL homepage for details. IDL 6.3 or later is needed for large file support on a Mac.

Download and Installation of GBTIDL

• To obtain GBTIDL, download the files here
• Create a directory for the installation and unzip the tar ball:

    mkdir mygbtidl
    mv gbtidl-2.3.tar.gz mygbtidl/.
    cd mygbtidl
    gzip -d gbtidl-2.3.tar.gz
    tar -xvf gbtidl-2.3.tar

• go to the top level directory, 'gbtidl':

    cd gbtidl

• copy 'run_gbtidl' to 'gbtidl':

    cp run_gbtidl gbtidl

• edit the 'gbtidl' script to replace "PLACE_INSTALLATION_DIR_HERE" with the full path to the gbtidl executable script. It should then look something like this:

    export GBT_IDL_DIR=/home/mygbtidl/gbtidl

• start the package by calling the script 'gbtidl':

    ./gbtidl

• You may wish to add the installation directory to your unix path.