The image is a map of the entire sky at the radio wavelength of 21-cm (or 1420 MHz radio frequency). The data is from the 21-cm maps presented by
Dickey and Lockman in the Annual Review of Astronomy and Astrophyscs, 1990, Vol. 28, p215. The brightest radio sources are marked. These are the sources that are easily detected with the SGRA 4.6-m radio telescope. Click on a radio source to learn more about it.
If you are interested in other objects not shown here, we recommend going to the NASA service called SKYVIEW which accesses catalogs of astronomical sources across the electromagnetic spectrum.