Number 15 June 2001


1) Gyro fails, but FUSE does not miss a beat  
2) Large Crop of Cycle 3 Proposals Received  
3) Recent FUSE milestones
4) Possible focusing targets solicited  
5) New Web interface to the FUSE project at JHU

1) Gyro fails, but FUSE does not miss a beat

        The Y axis of the FUSE primary gyro package (IRU-A) failed at 12:06 am 
EDT on May 30, 2001 causing an entry into Safe Pointing Mode. The attitude 
control system in response autonomously switched to IRU-B. The inertial science 
mode was recovered at 3:20 pm EDT.  The FUSE satellite returned to the science 
timeline and resumed normal science operations at 11:50 pm May 30, less than 24 
hours after the gyro failure. The FUSE satellite and ground system were designed 
to efficiently recover from such a failure, and all systems worked as planned.  
Following the switch to IRU-B, pointing and slewing recalibration of the 
attitude control system was completed during the week of June 4.  The behavior 
of IRU-B seems to be at least as good as IRU-A.  The X and Z axes of IRU-A are 
still functional and available for future use with IRU-B in a cross-strapped 
mode, should IRU-B experience a similar problem at some point in the future.

        With the nominal performance of IRU-B and numerous contingencies 
available or under study, such as cross strapping gyros between the two IRU 
packages, we anticipate full functionality of FUSE well into the future, making 
it highly likely that the extended mission will be carried out as planned.

2) Large Crop of Cycle 3 Proposals Received

        In response to the NRA, NASA received 178 proposals for observations 
during Cycle 3 of the FUSE mission (December 2001 - November 2002).  The total 
time requested is approximately 15 Msec, compared to the 5.7 Msec that is 
expected to be available.  The proposals will be reviewed this summer.  NASA 
expects to announce the results of the review in September 2001.

3) Recent FUSE milestones

        We'd like to share a few milestones with you about the progress of the 
FUSE mission:

        Orbit 10,000 occurred on May 17th and we have so far acquired 462 
GI and 959 PI science observations.  Of these 842 are already in the public 
domain accessible through the MAST system at STScI.  Note also that June 24 
will mark the second anniversary of the FUSE launch.

        More than 30 scientific papers based on FUSE data have already 
appeared in refereed journals with many more submitted.  In addition, more than 
150 conference contributions and similar papers have been produced with 23 
appearing at the recent AAS meeting in Pasadena.

        A tally and listing of FUSE related publications can be found at 
Alex Fullerton's "FUSE Publications Summary" page:

4) Possible focusing targets solicited

        It has been over a year since we last focussed FUSE, and it is time to 
do it again. The success of this depends upon finding the best possible target.

        The ideal target would be one whose spectrum displays intrinsically 
narrow absorption lines across the spectrum.  TTAG data is greatly preferred 
over HIST data, because the sampling is at the full detector resolution, the 
grating and Doppler corrections are better, and a proper correction can be made 
for gain sag.  However, high S/N is essential, so targets near the TTAG bright 
limit are preferred.

        A spectrum with narrow (but safe) emission lines offers many advantages 
over an absorption line spectrum. The problem is that there are usually not 
enough lines to get good data across the band. But such a a spectrum might 
still be quite useful as a check, as well as to investigate the FUSE line 
spread function.

        If you are familiar with a dataset or target that might be useful for 
obtaining focus data, please call it to the attention of Scott Friedman at JHU 
(  The object or objects selected for this purpose will be 
observed with lengthy exposure times, probably longer than in the originally 
proposed program, and the resulting dataset should be excellent.

5) New Web interface to the FUSE project at JHU

        A new and improved web-interface for the FUSE project at JHU is in the
final testing stage.  We expect to unveil it by the beginning of July.
Not only will the new interface provide a new fresh look to our home page, but
we hope that it will make the site easier to navigate.  
Please "surf" over there in July and tell us what you think.
The URL of the site will remain:

(Send comments and suggestions to

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. J.B. Joyce, 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;

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