A new adaptive optics system has been built at the University of Hawaii. It is equipped with a 36-actuator deformable mirror and a 36-element lenslet array, both developed at the Institute for Astronomy under NSF grant AST-9618852. Wave-front sensing is done with 36 photon counting avalanche photodiodes (APDs). For this first observing run, 24 of them were new actively quenched diodes from EG&G. The remaining 12 were passively quenched diodes. The gain in photon counts due to the new APDs was found to be by a factor 1.73. In the future, all 36 diodes will be of the actively quenched type.
The new AO system is called Hokupa'a, the Hawaiian name for Polaris, which means steady star. Hokupa'a was mounted on the CFHT f/35 focus, and used for 11 nights from November 7 to November 17, 1997.
