The effect of the Sun shining on the surface

On 20050420 two 80 GHz maps were made. The first map in the morning at 08h33m HST with the Sun behind UKIRT shining on the dish and heating the front of the telescope. The second map was made in the evening at 17h28m HST. The maps are shown in the first two figures below. The first map is rather ugly. The aperture rms is 36.4 micron, but the adjuster rms 49.4 micron. The aperture and adjuster rms of the evening map are 28.6 and 30.4 micron respectively.
The third figure shows the difference map 083335-172845. It shows a very regular pattern within almost all panels. The rms of this difference map is 35.3 micron. The deviation is typically -40 micron in the center of the panels and close to 0 at the edges. The exception are panels in the top and bottom of the dish, where the trend is the same, but the deviation in the center of the panels is small and positive at the edges. This difference can be due to other effects (temperature gradient differences) between morning and evening.
If I am not mistaken about the sign, this means that in the morning map the centers of the panels have a deviation towards UKIRT (outwards) compared to the evening map. The cause of the deviation could be bending of the panels: the front of the panels are heated more than the back and expand. It is not possible to correct for this effect, other than not observing towards the sun. As far as I know this is the first time that this has been measured in surface maps (with RxH3 most holography has been done in the evening because of scheduling of surface shifts).
Some panels in the same ring apparently are more rigidly connected than other panels because there is no minimum in between them.