This is lower than a good 'seeing' (1 arcsec). A seeing of 1 arcsec means a ponctual object appears as a ~1 arcsec diameter disk. It depends on the conditions
of the atmosphere (turbulence). For example the night I did my observation (19th January 2002) there was a lot of wind so the seeing was about 2-3 arcsec.
So the object I observed which could be Nibiru had a diameter lower than 2 arcsec. So, Nibiru is still very difficult to detect, and needs a very good sky
('seeing') : the larger the seeing is, the fainter the object appears (the seeing spreads the intensity). That is why it is possible that Nibiru could be undetectable on
Steve's images. See the image below to compare : Uranus is about 3.6 arcsec.