Hokupa'a Performance Calulations: AOWFS Source Extent

This dependence is very difficult to quantify for the following reasons: (1) extended guide 'stars' come in all shapes, sizes and brightnesses, and (2) with only an extended source in the field, it is difficult to estimate what the performance is. We have engineering tests planned to provide more guidelines but for now the following information may be of use.

We have successfully used the cores of M32, NGC7626, and NGC7469 as Hokupaa wavefront reference sources. The performance on M32 was FWHM ~ 0.12" in H and in K. The performance on NGC7626 and NGC7469 is unknown.

We were not able to use the core of NGC7768 (a classical r^1/4 law cD elliptical with a core FWHM of ~1.2") with Hokupaa.

Note that for targets using extended guide 'stars', a separate PSF calibration will likely be very different since the wavefront sensor source is dissimilar.

Last update 24 August 2000; Mark Chun
In original form; Mark Chun