Number 24, March 3rd, 2003


1) FUSE Cycle 4 results
2) Fourth Annual FUSE Science and Data Workshop, May 12-13, 2003
3) Scientific Results of the FUSE Mission, Victoria, B.C., August 2-6, 2004.
4) Detector 2 High Voltage Anomaly, December 8, 2002 - February 3, 2003.
5) CalFUSE v2.2.3 released

1) FUSE Cycle 4 results

        NASA announced the results of the Cycle 4 Guest Investigator proposal 
review at the end of January 2003.  The observing programs selected for Cycle 4 
are posted on the FUSE GI web page (  The Cycle 4 targets 
listed on the same site correspond to the proposed target lists of accepted 
programs, corrected for duplications between Cycle 4 programs and target 
restrictions as a result of the peer review.

        A total 179 proposals were submitted for Cycle 4 in two categories, 
Standard (164 proposals, 16.4 Msec) and Survey/Supplementary (13 proposals, 
3.6 Msec).  NASA accepted 99 Standard proposals (6579 ksec, including 310 ksec 
for TOO programs) and 13 proposals in the Survey/Supplementary category (2453 
ksec).  Even the number of submitted and accepted Survey proposals are the 
same, not all Survey proposals were accepted.  Several proposals submitted in 
the Standard category were accepted as Survey programs.

2) Fourth Annual FUSE Science and Data Workshop, May 12-13, 2003

        We would like to invite all new and seasoned FUSE users to the fourth
Annual Science and Data Workshop, planned for May 12-13 in Baltimore.  We are
planning about half a day of operations and programmatical updates followed by
presentations on science and data analysis.  We invite those interested in 
giving a presentation to contact us at with a suggested
subject.  We're expecting to have both oral and poster presentations with the 
oral presentations nominally planned as 30 min. talks.  This year the workshop 
will run two days to be followed by a meeting of the FUSE Observer's Advisory 
Committee (FOAC) on Wednesday, May 14.  So this will also be a good opportunity 
to come and meet your FOAC representatives!

3) Scientific Results of the FUSE Mission, Victoria, B.C., August 2-6, 2004.

        Please mark your calendars for a week-long symposium on the scientific 
results to date from the FUSE mission, scheduled for 2004, August 2-6, 
in Victoria, BC, Canada.  This conference will cover a wide range of 
astronomical research. There will be invited reviews, contributed talks, and 
poster papers.  Further details will be forthcoming during the spring and will
be noted in future newsletters as well as on the FUSE web site.

4) Detector 2A High Voltage Anomaly

        Every six to twelve months, we raise the voltage on the FUSE detectors
to compensate for the effects of detector gain sag.  We did this most recently 
on 8 Dec. 2002.  Shortly afterward, detector segment 2A began to experience 
high-voltage current transients, which resulted in a shut down of the detector 
2 high voltage.  Repeated attempts to return the voltage to its nominal level 
were unsuccessful.  On 16 Dec. 2002, we decided to leave the voltage on segment 
2A at a lower-than-nominal value while we investigated the problem.  We were 
finally able to return segment 2A to its pre-December voltage on 3 Feb. 2003.

        Calibration data indicate that LiF 2A LWRS spectra obtained during this
low-voltage period suffer significant walk effects, with typical shifts of 20 
to 30 pixels in the raw data.  The other LiF apertures (HIRS and MDRS) and the 
SiC channel of segment 2A are much less affected.  The CalFUSE pipeline 
corrects time-tag data for walk, but the correction for histogram data is less 
satisfactory.  Observers are urged to examine carefully LiF 2A LWRS spectra 
obtained in histogram mode during this low-voltage period.

        The low pulse heights seen in LiF 2A LWRS spectra have a second effect
on FUSE data: detector background events, which generally have lower pulse 
heights than actual photon events, may fall below our low-pulse-height 
threshold.  As a result, the detector background is reduced, and our 
background-subtraction modules -- which scale models to the background measured 
on regions of the detector with a more normal pulse-height distribution -- may 
over-estimate its intensity.  This anomaly affects LiF 2A LWRS spectra obtained 
in both time-tag and histogram mode.

The instrumental sensitivity shows no significant change during this 
low-voltage period.  For more information, please see the CalFUSE White Paper 
"Time-Dependent FUSE Calibration Effects" at

5) CalFUSE v2.2.3 released

FUSE data are now being processed at JHU with CalFUSE v2.2.3, a mild
upgrade from CalFUSE v2.2.2.  We have corrected a few bugs and made the
pipeline more robust when dealing with really weird data.  We've also
updated the VOLT_CAL files to reflect detector-voltage changes over the
past three months.  If you would like to upgrade to CalFUSE v2.2.3,
see the CalFUSE web page at

The Observer's Electronic Newsletter is published 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;

Retour à la page d'accueil