August 25, 1996

News from UKIRT

Dear all,

As the commissioning run is almost over and I have to jump on a plane immediately after getting up tomorrow afternoon, here is a brief summary of the last two weeks.

By now, everybody will know that the system works very nicely. Everything, from the new top end with the hexapod, to the bottom end with the cross head and the tip-tilt sensor, runs flawlessly, with the exception of the sky shutter that was taken off the telescope, let's say, for fine tuning. We managed to produce images with a FWHM of 0.25'' (down from 0.5'') and a Strehl of 12% (up from 5%).

One can now do tip-tilt correction on both ends of the chop, and, in a last day effort, we solved the problems with the adaptive focus correction. However, this will require some more work before it can be released to the user. The reason is that the focus throw of the secondary mirror is too small to correct for the focus changes due to the atmospheric turbulence. The piezos can move the mirror over a focus range of 10mm in the cass focus but about 30mm peak to peak movement are required. As the large strokes are rather slow, we hope to be able to compensate them with the hexapod.

I would like to take the opportunity to thank our colleagues at the JAC and the ROE for the very pleasant collaboration over the last 4 years. And I would like to congratulate Tim Hawarden, Nick Rees, Tim Chuter, Chas Cavedoni and Kent Tsutsui for improving UKIRT in many ways, not the least in making 0.25'' images possible. The last two weeks have not only been hard work but also a lot of fun.

Best wishes,

Andreas Glindemann