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   INFORMAL ELECTRONIC NEWSLETTER FOR THE EUVE SCIENCE PAYLOAD
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    Volume II, Number 1                          July 1, 1992
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EUVE OBSERVATORY IS OPERATIONAL _ WORKS GREAT
by Roger F. Malina

Every morning I walk into work and ask "What did we discover last
night?"

The EUVE instruments have now completed their initial in orbit
checkout and I am pleased to say that all instruments are working
with no significant problems. The data analysis pipelines are
working smoothly ( processing time is 45% of real time, compared
to our pre-launch goal of 30% of real time).

I can report that we have "several" possible new EUV sources that
EUVE  has  discovered. We are currently analyzing these in detail
to make sure they are real. Ironically, we  had  not  planned  to
start  analyzing  data for new sources until the start of the sky
survey beginning July 22, but we may be able to announce new  EUV
sources  before the actual start of the mission !!!! As a word of
caution, the first new EUV source we thought  we  had  discovered
proved  to  be  an  artifact  because  of  the  numerous pointing
maneuvers during the checkout period that led to some confusion
initially in the data reduction.           We will make sure that
we do not release new source announcements until we have scrubbed
the data back very hard. Watch this space.

We now have several calibration  spectra  in  hand.  Analysis  of
these  spectra  is going on for performance verification (we have
had to make sure that  data  that  may  belong  to  GO's  is  not
released  accidentally).  Initial  performance analysis indicates
that the instrument throughputs  and  backgrounds  are  close  to
those described in the EUVE Observers Handbook. The spectra are
BEAUTIFUL.  The instrument alignements have now been measured
from the in orbit data and we are setting the alignment offsets.

Initial performance analysis has also been  carried  out  of  the
EUVE  background, comparing these to models of the geocoronal and
geophysical background. The models match the data well and  indi-
cate  that  the solar EUV is somewhat fainter than we had assumed
in our conservative assumptions.  The  initial  analysis  of  the
charged  particle  background  indicates that our magnetic brooms
and repeller grids are working well to exclude the charged parti-
cles. We are seeing very very low countrates down the earth's
shadowcone indicating that the EUVE deep survey is likely to be
very very sensitive. I overhead someone say the other day "Is
this real data or is it simulated ?". It is very hard to tell the
difference !

On the engineering front we are working on a number of small  is-
sues  on  the performance of the instruments. These have all been
reported in the daily reports and pose no threat  to  science  or
health  and  safety. We continue, for instance, to see occasional
short-lived bursts (under a few seconds) where a single  detector
count rises to above a 1000 c/s (from the usual 10- 100 c/s).
These may be related to the major solar storm  alerts  that  have
occurred over the past ten days. We also see occasional events
due to high energy charged particles. These overload our
amplifiers and are mis-imaged. We are currently adjusting the
detector thresholds to eliminate these events. In the early days
of the instrument checkout, one of the detectors (Scanner A)
went into a soft scrub mode - this resulted in an enhanced background
for a few days but the detector is back to normal count rates
and operating fine.

We have no new pinholes that developed during launch or the two and
half year integration period since we delivered the instruments
to NASA. We do see the two pin holes that we had seen and calibrated
during ground test. The image from the pin hole mimicks the ray tracing
model runs that we had carried out. The detector backgrounds are
very smooth with no significant detector hotspots other than the
few very faint ones that we already knew about.

Last week we safed our instruments in anticipation of the
solar eclipse. We were concerned that our software might
get confused by the additional "day/night" commands that
we would receive as we went in and out of the eclipse. As
it turned out, before we went into the eclipse we received
a "safing" command from the spacecraft because a planned
slew had overshot a safety limit. It took us 13 hours to
get all the instruments reset and operational again- I
am sorry to report that the GSFC Flight Operations Team
were able to get the spacecraft itself operational again
in a few hours and beat us to the punch. We will do
better next time ! Or better - the next time may never occur.

The EUVE spacecraft has been operating very smoothly from
the science instruments point of view. We have been watching
the anomaly resolution on one star tracker and overheating of
the gimbal motors on the antenna. These anomalies now seem to be controlled
and the spacecraft operations is going very smoothly. The
GSFC Flight Operations Team is doing great- maybe its true
that data solves all problems. Certainly the pre-launch
friction on mission operations has evaporated as the data
has started pouring in.

The EUVE instruments are working according to  plan.  We  are  on
schedule  for  the  In-Orbit  Calibration    and     will
start the sky survey as scheduled on July 22/23.

The excitement around here is palpable. We have a first rate  ob-
servatory in EUVE and we look forward to reporting our first sci-
ence results. We hope you all got your GO proposals submitted by
the deadline of July 1 - the EUVE Guest Observer Support Group
has done their first release of the GO software under IRAF and
is ready to start distributing data as soon as the GO program
starts in January. The GO software package has been used to
reduce the in-orbit calibration data and is running very well.

I remember the excitement here in 1975 during the Apollo-Soyuz
mission when the first non-solar EUV source was discovered.
Stu Bowyer, Mike Lampton, Bruce Margon, Francesco Paresce,
and Bob Stern reported that the star HZ43 "blew them off the
console". That was July, 17 years ago. On the sand at Cocoa
Beach they dreamed of building a satellite dedicated to
EUV astronomy.  The last window on the Universe.... EUVE is
now in orbit. Its even visible in binoculars in the evening sky.
Only Stu Bowyer and Mike Lampton from the original team are still
here at Berkeley to enjoy the thrill of discovery in real time,
and numerous scientists who have "done time" on EUVE are spread around
the country and abroad. Your observatory is now in orbit ! Thanks for your
help- we look forward to welcoming you back to Berkeley to enjoy
the discoveries.


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The  EUVE  Electronic  Newsletter  is  issued  by  the Center for  
Extreme  Ultraviolet  Astrophysics,   University  of  California, 
Berkeley. The opinions expressed  are those of the authors.
Publisher: Roger F. Malina,  Managing Editor: Camille Trentacoste
      Funded by NASA Contracts NAS5-30180 and NAS5-29298.
Send newsletter correspondence to: pub@ssl.berkeley.edu (Internet)
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The EUVE Project is managed by NASA's Goddard Space Flight Center
in  Greenbelt, MD.  The EUVE Project Manager at GSFC is Mr. Frank
Volpe, the GSFC Project Scientist for EUVE is Dr. Yoji Kondo, the
Deputy Project Scientist is Dr. Ronald Oliversen. The NASA  Head-
quarters EUVE Program Scientist is Dr. Robert Stachnik, the Depu-
ty  Program  Scientist is Dr. Derek Buzasi, the NASA Headquarters
EUVE Program Manager is Mr. John  Lintott.   Information  on  the
EUVE Guest Observer Program is available from: Dr. Yoji Kondo,
Mail Code 684 GSFC, Greenbelt, MD 20771 (301) 286-6247 -
euve@stars.SPAN.NASA.GOV
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