This document describes the spectral line system at the NRAO1.1 Very Large Array (VLA). It is directed at users who already have an understanding of aperture synthesis imaging. The user should be familiar with the proceedings of the Synthesis Imaging workshop (hereafter referred to as SIRA). Another excellent book to consult is ``Interferometry and Synthesis in Radio Astronomy''. These sources as well as useful VLA memos are listed in chapter 4.
Versions 1 through 8 of this guide were produced by Arnold Rots, the latest version having appeared in 1990. The current version 9 is a complete rewrite and supersedes all previous versions.
A summary of the capabilities of the VLA for continuum as well as spectral line users is provided by the Observational Status Summary (OSS) which contains a list of key personnel to contact in case of further questions. The OSS is released once a year and can be obtained through NRAO's World Wide Web pages for the VLA1.2 or by contacting the NRAO for a paper copy. To avoid unnecessary duplication of information and to prevent the current document from becoming rapidly out of date, frequent reference will be made to the OSS. We also refer to the observe program which is used to provide instructions to the on-line system. The OSS provides details on how to retrieve this program and assorted manuals via ftp.
This guide concentrates on topics of which one should be aware when preparing for a VLA observation and leaves post-observation issues to other documents. The answers to many data reduction questions can be found in the AIPS Cookbook. That document provides an introduction to the Astronomical Image Processing System (AIPS).
If you are unfamiliar with new developments in the spectral line system or if you are a new user of the VLA it is strongly recommended that you visit the AOC and spend a couple of days preparing for your observations and stay at least a week after your observations in order to reduce your data. Try to make reservations as early as you can (i.e., several weeks in advance, but give at least one week's notice) to ensure that you will have the help and computer facilities that you may need.