Daniel Fabricant
Smithsonian Astrophysical Observatory (SAO)
A member of the Harvard-Smithsonian Center for Astrophysics (CfA)

Wide Field Corrector Status

January, 2001. The corrector optics have been antireflection coated with Sol-gel by Cleveland Crystals. The reflectivity of a test sample is shown in this graph. We thank Robert Dew of Cleveland Crystals for his leadership of this project, and the staff and management of Cleveland Crystals for their sustained effort.

The corrector cell has been assembled at the Center for Astrophysics. Following the addition of the axial mounting pads and the completion of a few covers, it will be sent to BF Goodrich Optical Systems (formerly Raytheon Optical Systems, Hughes Danbury Optical Systems, Perkin Elmer), where the optics will be mounted.

June 23, 2001. All the axial mounting pads have been tested and bonded in place. The six edge baffles to absorb scattered light have been mounted into the cell, and all the mounting hardware and covers have been checked out. The Atmospheric Dispersion Compensation (ADC) prism rotators have been run, and the ADC prism stepper motor control software has been tested. The cell components will be delivered to B.F. Goodrich Optical Systems in Danbury, CT by the end of June.

June 12, 2002. The three completed lens assemblies have been packed up and loaded into a truck for shipment to Arizona. The truck is also carrying carts and handling fixtures.

June 14, 2002. The corrector has arrived safely in Arizona and has been placed in storage pending the completion of the f/5 secondary and its support.

April 20, 2003. The corrector has been delivered to the MMT and set up on its handling carts. The ADC prisms have been tested with their electronics at the MMT. The corrector has been test fit on the telescope and is awaiting the completion of the commissioning of the bare f/5 focus. We anticipate that corrector commissioning will begin in May.

May 22, 2003. Initial tests of the corrector in its spectroscopic configuration have been completed. The corrector produces excellent images across the entire 1 degree field. During this May commissioning run we also verified that the ADC prisms produce the specified correction, and closed the loop on the primary mirror axial supports with the f/5 wavefront sensor. On-axis, we recorded images as good as 0.38 arcseconds FWHM during short exposures of a few seconds. At the edge of the 1 degree diameter spectroscopic field the images were as good as 0.58 arcseconds FWHM.