Number 2 October 1998


1) Puerto Rico ground station damaged   
2) FUSE satellite testing
3) Use of HIRS vs. MDRS slits
4) Phase 2 submissions

1) Puerto Rico Ground station damaged
        The FUSE ground station in Puerto Rico caught the wrath of hurricane 
Georges almost straight on.  The dish was blown off its mounting and was left 
hanging by some cables.  The full extent of the damage is not yet known.  
However, while repairs to the Mayaguez station are being pursued several 
alternative downlink options are being studied.  Although the situation is 
still developing, we do not at this time expect this mishap to have any 
significant impact on the FUSE schedule or science.  We'll keep you posted 
as more information becomes available.

2) FUSE satellite testing

        Testing of FUSE is proceeding at GSFC.  Vibration and acoustic testing 
were successfully completed in September.  Instrument functional and 
performance tests are on-going and simulations of mission operations will 
start next week.  We expect thermal vacuum testing to begin about mid-October.

Please see the Satellite Status page:

3) Use of HIRS vs. MDRS slits

        There has been some confusion regarding the expected relative data 
quality from the HIRS and MDRS slits. As has been pointed out in the 
FUSE Observer's Guide, the spectroscopic resolving power using the MDRS slit 
is not all that different from the HIRS slit, while providing a significantly 
better throughput (98% vs. 67% or almost a factor 1.5 in exposure time savings 
for a given Signal-to-Noise!)  
        Assuming a MDRS PSF of 0.65" and a pointing jitter of 0.5" 
we find, by convolving the two, an effective PSF through the MDRS of 0.82" or 
R=24,000 or dv=12.6km/s, compared to R=30,000 or dv=10km/s for HIRS (note that 
this example is even more conservative than the Phase 2 Instructions which, 
based on ray-tracing analysis, predicts R=27,000 or dv=11.2km/s). 
If your program involves observations of faint targets and the highest
possible resolution is not required, we urge you to specify the MDRS aperture
on these targets.
        Also, since the MDRS slit does not require PEAK-UPs (the satellite 
pointing is expected to be good enough to put your source in the MDRS slit, 
while not necessarily in the HIRS slit) the use of MDRS is operationally both 
simpler and "safer" - remember; if a PEAK-UP fails due to incorrect flux 
estimates, YOU will still be charged for the observation (since FUSE will be 
observing autonomously, we will not know until after the fact that the target 
acquisition failed).

4)  Phase 2 submissions

The diligent GI community has found a few "gotchas" in the phase 2 parser.  
Specific examples include:

-Use of colons (:) in text fields can cause parser errors
-Offset star entries (parser returns somewhat confusing error messages)
-The "expected_ct_rate" should include all sources of detector signal.
-If you enter comments or text anywhere in your template file that are not
intended for printing (i.e., outside of the requested text blocks), make sure 
the lines are commented out (put a pound sign [#] at the beginning of each line)
or the parser will crash.

Please see the NEW(!) web pages under "Observer's News and FAQs"
( for details  (specifically 
"Phase 2 Frequently Asked Questions";

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;

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