Another image-degrading effect is that due to strong nearby sources. Again, the 20 and 90 cm bands are especially affected. The active Sun will be visible to any D configuration daytime spectral line observation at these bands. Even with 50 MHz bandwidth in continuum mode, the active Sun can ruin the short spacings of observations within about 20 degrees of the Sun. The quiet Sun poses a lesser threat, so the general rule is to go ahead and observe, even if the target source is close to the Sun. At 90 and 400 cm, observations within approximately 10 degrees of Cygnus A, Cassiopeia A, Taurus A, and Virgo A will be greatly degraded.