Introduction

The SMA online data computer takes spectral data from correlator and store the multiple spectral-band data into a file following the SMA Data File Format. The frequency configurations of SMA data are complicated and flexible. The SMA Passband Visualizer provides web-based graphic tool to set up frequency configuration across the SMA passband with a total number of spectral bands per sideband 25, 49 and 51 for the 2 GHz, 4GHz and 8 GHz (near future) modes, respectively. A spectral band here can be either a correlator chunk (spectral window) or the pseudo-continumm channel ( a single channel that is a vector-average from all the channels of the spectral bands). In principle, the number of channel and channel width (or spectral resolution) in each of the spectral chunks can be different. The Miriad along with SMA software features supports such flexibility in the configuration of spectral data. In order to handle a large number of spectral windows in Miriad a few of original Miriad codes are modified by adding new software features. To distinguish the spectral data between different spectral chunks (or windows) and different sources, both spectral windows and observing sources are coded with colors in various displaying routines. The following sections show demonstrations of processing SMA data in Miriad.