We now have good radial profiles of Altair and Menkab. Altair was observed in very good conditions, and its profile is close to the expectation of r^-3 for the diffraction limit — in three of the 5 bands. In B and VE1 funny things are happening which we don’t yet understand. The Menkab profiles have halos like r^-1.5 — much broader. The plots below compare both stars:
We think that Menkab might have been taken on a not-quite-perfect night photometrically. We’re looking into this, so watch this space!