There is an ‘integrating sphere’ in the dome at MLO and we can now use it for flat field observations. Preliminary results suggest that the problems with gradients are as procounced as with other methods, and that the ‘interference pattern’ seen in VE2 with other methods are different when seen using the lamp.

The ND0.9 filter was also used and flat fields attempted – but maybe the shutter is prone to sticking during long exposures and the low temperatures we had today (4-5 degrees C).

The lamp is at Altitude 4 degrees and Azimuth 291 degrees. Some experimenst should be performed to find the best alignment.