| Back 1 | Back 2 | Map | Glossary | Information |
Baselines: 6 dishes; 12 dishes
JPEG Image (30K)
An array comprising of several dishes can emulate a much larger, single-dish telescope. By combining the incoming signals, astronomers can generate high quality images. This technique is called radiosynthesis interferometry and is illustrated in the following movie.
As its name implies, the technique relies the phenomenon of interference between the incoming radiowaves due to their slightly different arrival times at each of the array's dishes. The rich information contained in the patterns of interference must be extracted with the aid of powerful computers.
But the utility of an array depends on more than its sheer numbers of baselines. That's in part because each baseline has a corresponding spatial resolution. Long baselines result in high spatial resolutions while short baselines yield low spatial resolutions.
Although it is generally preferable to use a large number of baselines, it is better to have fewer, variable baselines than many of the same length. After all, each baseline length provides a unique spatial resolution that, in turn, determines the level of detail revealed by that baseline. Consequently a variety of baselines permit imaging at different levels of detail.
For observational purposes, the dishes in the BIMA array are set in only one of three configurations along a T shaped track. Each configuration allows for different spatial resolutions, according to its baseline lengths. Thus the BIMA array can be used flexibly to observe both large and small scale structures in the same object.
Return to Spatial Resolution
Return to Arrays Lose Large Scale Structure