Number 4, December 1998


1) Ground station(s) update 
2) Satellite gyros
3) FUSE satellite testing
4) Season's greetings

1) Ground station(s) update
	The repairs to the main FUSE ground station in Puerto Rico after the
hurricane damage, are proceeding well.  Retest of the UPRM station is scheduled
for early February!  The Universal Spacenet station in  Hawaii, which FUSE will
also use,  earlier this month successfully supported the SWAS launch, 
indicating that it's up and ready to fulfill its FUSE support role as well.

2) Satellite Gyros
	The vendor for the inertial reference units (IRUs), which contain the
gyroscopes, is actively working on the problem which we discussed in
last month's newsletter.  They believe they have identified and fixed the 
problem, and testing is underway to demonstrate this.

3) FUSE satellite testing

	The FUSE satellite has been undergoing extensive testing in the
thermal-vacuum chamber at Goddard for several weeks now. As part of this, an
optical end-to-end test was started on November 28 and ran through December 4.
The purpose of the test was to exercise techniques for aligning and focusing
the instrument on-orbit, and to see how the full instrument responds to a UV
light source.

	The co-alignment and focus procedures worked very well. The data 
indicate that the spectral resolution is about what we expected.  The telescope
image size is harder to interpret because we don't have an independent measure
of the collimator source imaging quality at FUV wavelengths. So while the error
bars are fairly large, the telescope mirrors appear to be performing at close
to their specified quality.

	One important problem was discovered during these tests. The structure
was found to distort more than predicted as its temperature changes. This is
thought to be due to four bars running the length of the spectrograph which
warp the grating bench as they expand or contract with temperature. A design 
fix has been identified which should eliminate the warping and the resulting 
focus and spectral location changes. Once some new parts are fabricated, the
modification will take less than a day to complete.  This will be followed by
another optical end-to-end test to verify that the problem has been solved.

Aa usual, test reports can be found at:

4) Season's Greetings from the FUSE project
	Finally, let me pass on very warm season's greetings from all of us 
here at the FUSE project, with wishes for a prosperous and data filled new 

Please come by and see us at the FUSE booth during the Austin AAS meeting!

The Observer's Electronic Newsletter is published Monthly by the FUSE project
and is aimed at the FUSE user community.

Editor: B-G Andersson, FUSE Guest Investigator Officer.

The FUSE Project is managed by Johns Hopkins University's Center for 
Astrophysical Sciences in Baltimore, MD, for NASA's Goddard Space Flight 
Center.  The FUSE Principal Investigator is Dr. Warren Moos, the FUSE Project 
Manager at JHU is Mr. Dennis McCarthy, and the NASA Project Scientist for FUSE 
is Dr. George Sonneborn.

Further information about the FUSE Guest Investigator Program can  be
obtained from:  Dr. George Sonneborn; sonneborn@stars.gsfc.nasa.gov

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