Major improvements in telescope performance and reliability were made to the Vatican Advanced Technology Telescope (VATT) under the Science Initiative Grant awarded to the Vatican Observatory Foundation by the Kresge Foundation in December 1998. The final technical report for this grant was presented to the Foundation on 1 March 2000, and it is available on the Observatory website. The report includes many photographs and summary descriptions of the technical advances completed and those still underway. The Kresge Foundation grant made it possible to make progress on the VATT improvements at an exciting and rewarding rate. Support for this work continues through the concurrent and subsequent successful fundraising by the Vatican Observatory Foundation.

A radar dish, part of a precipitation detector system fabricated through the Kresge grant, stands guard outside the VATT. The detection electronics are at right. The system senses weather conditions a kilometer or more above the VATT and triggers an alarm to warn observers of any unexpected bursts of rain or snow that can damage the telescope's primary mirror. (Photo by Christopher Corbally, S.J.)

Principal contributors to the VATT improvements during the past year include the following people from the University of Arizona Steward Observatory: scientists CROMWELL and NELSON; engineers McKENNA, BRAR, CORDOVA, DAVISON, and LANDGREEN; technicians FRANZ, SWIFT, PHILLIPS, and TARDIF; several technical people from the Steward Observatory Technical Services group, directed by DeRIGNE; and people from the Mount Graham International Observatory operations crew, directed by RATJE.

Other recent VATT advances, aside from those described in the Kresge report, include: the discovery and elimination of servo tuning errors in the elevation drives (and lesser errors in the azimuth and derotator drives as well), resulting in improved star-tracking performance; the addition of black felt baffles in critical parts of the telescope optical path, resulting in the elimination of scattered skylight in VATT images and in a concurrent improvement in the accuracy of photometric measurements; the discovery and elimination of mechanical coupling between the dome building and telescope pier, resulting in reduced image motion due to vibration of the telescope in strong winds; and the discovery and reduction of vibration in the secondary-mirror mounting structure, resulting in reduced image spread due to secondary-mirror vibrations.

CORBALLY continued to maintain the Vatican Observatory website (http://clavius.as.arizona.edu/vo/), which gets an average of 150 visits per day, and added both the 1999 Annual Report and the Kresge Foundation grant final technical report. The Vatican Observatory website is included in the Wider View of Things, an interactive exhibit on science at the soon-to-open John Paul II Cultural Center in Washington, D.C.

In collaboration with KENNICUTT (Steward Observatory, University of Arizona), four interference filters were purchased for the VATT. The 3.47-in. filters are designed for H-alpha imaging and are being used principally by FUNES.

NELSON (Steward Observatory, University of Arizona), together with COYNE and MAG¶LHAES (Istituto Astron¢mico e Geof¡sico, University of SÆo Paulo), is designing a module for the measurement of polarization that will make it possible to carry out both point-source and imaging polarimetry with the VATT.