SN1006 was the brightest supernova in all recorded history, about four times as bright as SN1054. But it was a Type Ia, which expels relatively less material into space.
The remnant nebula from SN1006 has been found and is called G327.6+14.6, but it seems to be quite dim. No value is given anywhere in the literature for apparent magnitude.
(The peak apparent magnitudes were about -7.5 versus -6. M = -7.6 is about the brightness of the moon three days past new.)
All available images of G327.6+14.6 seem to be composite using x-ray or multiple x-ray, visible and radio bands.
The strange ribbon image is a high resolution subsection showing shock wave interactions at the outer edge of the ball image.
large image