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ELECTRONIC NEWSLETTER OF THE EUVE OBSERVATORY
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Vol 5, No. 11 27 Nov 1995 ISSN 1065-3597
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Notes from the Editor
=====================
by Brett A. Stroozas, ISO Manager
Welcome to the electronic newsletter for NASA's Extreme Ultraviolet
Explorer (EUVE) satellite, compiled and published monthly by the
Integrated/Intelligent Science Operations (ISO) group at the Center for
EUV Astrophysics (CEA) at the University of California, Berkeley (UCB).
The contents of this issue of the EUVE electronic newsletter are as
follows:
1. Science News
1.1 Recent EUVE Science Highlights
1.2 Abstracts of Recently *Accepted* EUVE Papers
2. Science Operations News
2.1 Cycle 4 GO Proposal Summary
2.2 Public Data Release for 1 Dec 1995
2.3 New IRAF/EUV and EGODATA Releases
2.4 EUVE Enters Safe-Hold Mode for the First Time
2.5 1:0 Transition in the ESOC
2.6 Recent Newsletter "Bouncing" Problems
2.7 EUVE Represented at Telemetering Conference
2.8 On-Line Access to EUVE
3. CEA Job Listings
To comment on or make suggestions for the EUVE electronic newsletter,
please send e-mail to ceanews@cea.berkeley.edu (Internet).
*************************************
***** CEA/EUVE WISHES YOU A *****
***** HAPPY THANKSGIVING SEASON *****
*************************************
The EUVE observatory performed well throughout the month of Oct
1995, conducting observations of the following Guest Observer (GO)
targets (alternate name and spectral type information taken from the
SIMBAD or internal CEA databases; "NOIDs" are unidentified objects):
===================================================================
Target Alternate Spectral Observation
Name Name Type GMT Date(s) Notes
===================================================================
PW And HD 1405 GV 27 Sep - 05 Oct 1995 ---
EUVE J0122-603 -------- NOID 27 Sep - 05 Oct 1995 RAP
Moon -------- SolSys 05 Oct - 05 Oct 1995 ---
CGCG 0212.0-0100 -------- ---- 05 Oct - 06 Oct 1995 ---
EUVE J2010+42.6 -------- NOID 05 Oct - 06 Oct 1995 RAP
RE J2013+400 EUVE J2013+400 WD-DA 05 Oct - 06 Oct 1995 RAP
kappa 1 Cet HD 20630 G5Vvar 06 Oct - 13 Oct 1995 ---
RXJ2117.1+3412 -------- PlanNeb 06 Oct - 13 Oct 1995 RAP
EUVE J2112+501 GD 394 WD-DA 13 Oct - 17 Oct 1995 ---
-------- -------- ---- 17 Oct - 18 Oct 1995 SHM
EUVE J2112+501 GD 394 WD-DA 18 Oct - 19 Oct 1995 ---
EUVE J0922+710 RE J0922+710 NOID 19 Oct - 19 Oct 1995 ---
EUVE_J0325+012 -------- NOID 19 Oct - 19 Oct 1995 RAP
Diffuse Bkgd -------- ---- 19 Oct - 23 Oct 1995 ---
HR 1817 HD 35850 F7V 23 Oct - 30 Oct 1995 ---
BL Hyi RE J0141-675 CV-AM 30 Oct - 31 Oct 1995 ---
EUVE J0143+103 -------- NOID 31 Oct - 31 Oct 1995 ---
EUVE J0139+099 -------- NOID 31 Oct - 31 Oct 1995 ---
EUVE J0205+093 -------- NOID 31 Oct - 31 Oct 1995 ---
===================================================================
Key to Notes:
RAP = simultaneous Right Angle Program (RAP) imaging observation
SHM = satellite in Safe-Hold Mode (all instruments off)
1. Science News
===============
1.1 Recent EUVE Science Highlights
----------------------------------
by Dr. Pierre Chayer, EUVE Scientist
Dr. J. Dupuis, Dr. S. Vennes, Dr. S. Bowyer, Dr. A.K. Pradhan, and
Dr. P. Thejll, performed a study of the local interstellar medium
(LISM) by using the extreme ultraviolet (EUV) spectra of the hot DA
white dwarfs Feige 24, G191-B2B, MCT 0455-2812, HZ 43, GD 71, and GD
153. All these spectra were obtained with the Extreme Ultraviolet
Explorer (EUVE) observatory, and they showed clearly the
photoionization edge of interstellar He I at 504 A.
Dr. Dupuis and his collaborators analyzed the EUV continuum spectra
of these stars with a grid of pure-hydrogen model atmospheres and, in
the case of Feige 24, G191-B2B, and MCT 0455-2812, with a grid of
models incorporating new opacities of C, N, O, and Fe from the Opacity
Project. They obtained new EUV-continuum-based estimates of effective
temperatures for their sample stars and, for the three
high-metallicity white dwarfs, they established the effects of heavy
element blanketing on the EUV continuum of these objects and on the
determination of effective temperatures.
They found that the ratio of the neutral column densities of
hydrogen and helium in the LISM is similar for five out of six stars
in the sample, but that Feige 24 may have a substantially different
value. The Feige 24 results suggest that the ionization state in the
LISM is inhomogeneous. Their measurements favor a higher degree of
ionization of helium relative to hydrogen and also indicate that
hydrogen in the LISM is predominantly neutral in at least two lines of
sight.
1.2 Abstracts of Recently *Accepted* EUVE Papers
------------------------------------------------
Included below are abstracts of EUVE-related papers recently
*accepted* for publication. For those papers authored by CEA
personnel, the CEA publication numbers are indicated. Unless
otherwise noted, researchers may obtain preprints of the CEA papers by
sending an e-mail request containing the publication number(s) of
interest to pub@cea.berkeley.edu.
Researchers are encouraged to contribute *accepted* EUVE-related
abstracts for inclusion in future editions of this newsletter;
abstracts or preprints will also be posted under the CEA WWW Home
Page. Please send all abstracts or preprints to
archive@cea.berkeley.edu.
--------------------------------------------------------------
SOLVING THE MYSTERY OF THE HEAVY ELEMENT OPACITY IN THE
DA WHITE DWARF GD394
M.A. Barstow, J.B. Holberg, I. Hubeny, T. Lanz, F.C. Bruhweiler,
and R.W. Tweedy
To appear in Monthly Notices of the Royal Astronomical Society.
The white dwarf GD394 is one of a very small number of bright hot
DAs which have detectable quantities of highly ionized heavy elements
in their spectra. Whether this material resides in the photosphere of
GD394 or is in the form of a circumstellar shell has been the subject
of much debate, with the large discrepancy between the published
radial velocity of the star and the measured velocities of the Si
III/IV lines having apparently settled the argument in favour of the
latter idea. However, GD394 is also the coolest DA white dwarf in the
ROSAT sky survey showing convincing evidence for the presence of
absorbing material which strongly suppresses the EUV continuum. This
result has reopened the argument about the nature of the silicon
lines. From a combined analysis of the IUE, HST and EUVE spectra,
coupled with new measurements of the photospheric radial velocity from
H-alpha data, we have established that the Si III and Si IV lines are
indeed photospheric. Furthermore, other heavy elements must be
present to account for the EUV opacity, but at levels below the
thresholds for detecting absorption lines in either far UV or EUV
bands.
--------------------------------------------------------------
HIGH TEMPERATURE TAILS: AN EUV(E) CATASTROPHE?
J.H.M.M. Schmitt, J.J. Drake, and R.A. Stern
To appear in Proceedings of IAU Colloquium 152, "Astrophysics in the
Extreme Ultraviolet", ed. S. Bowyer and R.F. Malina (Dordrecht:
Kluwer), 1996.
The differential emission measure (DEM) reconstructions of some
active and inactive stars show evidence for high-temperature tails in
the form of plasma with temperatures in excess of log T ~ 7.5 (cf.,
Mewe et al. 1995). Our analysis of Extreme Ultraviolet Explorer
(EUVE) and ROSAT PSPC data shows that such high-temperature tails are
caused by "continuum flux" not accounted for in the plasma emission
models used for the data fits. As a consequence, such models require
most of the emission measure be located at temperatures large enough
so that no lines can be formed. We use the DEM distributions derived
from EUVE data to "predict" the (non-simultaneously) observed ROSAT
PSPC spectra of two inactive stars, i.e., Procyon and Alpha Centauri
AB. These two stars have very soft PSPC spectra, and are therefore
most sensitive to detecting any additional hot plasma. We find that
DEM distributions containing only material at lower temperatures are
fully consistent with the PSPC spectra, and show that in the case of
Alpha Centauri a high-temperature tail required to produce the EUVE
"continuum" overproduces IJ band emission by more than one order of
magnitude. We conclude that the high-temperature tails are not real
and that there is no EUV(E) catastrophe. Rather we discuss the
possibility that the missing "continuum" is in fact produced by
spectral lines not accounted for in the plasma codes used for the
spectral modeling. This work has been supported by NASA contract
NAS5-30180.
--------------------------------------------------------------
INTENSE X-RAY AND EUV EMISSION FROM ACTIVE GALACTIC NUCLEI
J.P. Mittaz, R. Lieu, C.-Y. Hwang, S. Bowyer, and J. Lewis
To appear in Proceedings of IAU Colloquium 152, "Astrophysics in the
Extreme Ultraviolet", ed. S. Bowyer and R.F. Malina (Dordrecht:
Kluwer), 1996.
Statistical studies of a sample of active galactic nuclei (AGN)
detected at galactic H I column densities (N_H) less than 2.5E20
cm^(-2) by the Extreme Ultraviolet Explorer (EUVE) and ROSAT missions
are presented. It is found that the best fit power-law photon indices
of the X-ray spectra at 0.1-2.4 keV are anti-correlated with N_H. The
indices for the 0.9-2.4 keV range do not show such a correlation, and
are considerably smaller (i.e., flatter). We are led to conclude that
the simple spectral parametrization of AGN in the EUV and soft X-ray
passbands suffers from a systematic bias that tends to underestimate
the slope. The bias is less severe in directions of lower galactic
absorption. When extrapolated to the limit of N_H -> 0, the true
spectra of AGN would have photon indices > 3.5 for the 0.1-0.9 keV
range. This is evidence for a significant soft component in the X-ray
emission, with spectral excess much stronger than that suggested by
the average index of 2.4 for AGN detected by the ROSAT sky survey.
This work has been supported by NASA contract NAS5-30180.
--------------------------------------------------------------
THE UNIQUE VARIABLE LINE SPACE SPECTROMETER ON THE EUVE SATELLITE:
IN-FLIGHT PERFORMANCE AND SCIENTIFIC RESULTS
S. Bowyer
To appear in Proceedings of the SPIE. [CEA publication #679]
Until recently, spectrometer designs for use at extreme ultraviolet
wavelengths have been limited to grazing incidence Rowland
spectrometers and transmission gratings. In principle, the new class
of variable line-space spectrometers offer substantial advantages over
these classic designs. The Extreme Ultraviolet Explorer Satellite has
three variable line-space spectrometers as part of its scientific
complement; this is the first use of this class of device. The
results obtained have been quite noteworthy. The in-orbit performance
of these spectrometers are demonstrated with examples of the
scientific results obtained in this mission.
--------------------------------------------------------------
THE EUVE GUEST INVESTIGATOR PROGRAM
K. Anderson and B. Stroozas
To appear in NASA Science Information Systems (NSIS) Newsletter. [CEA
publication #681]
NASA's Extreme Ultraviolet Explorer (EUVE) satellite was launched
on 7 June 1992. The purpose of the mission is to do a six-month
all-sky survey in the extreme ultraviolet wavelength region (60-740
Angstroms), followed by a multi-year program of Guest Observer (GO)
pointed spectrometer observations. The survey phase of the mission
has been completed and EUVE is now beginning its third year of GO
observations. Proprietary rights on a large volume of EUVE data
expired in 1994 and more rights will continue to expire as the mission
progresses.
To encourage and promote scientific research using these unique
data sets, the Center for EUV Astrophysics (CEA) at the University of
California, Berkeley, is offering a Guest Investigator (GI) Science
Program. The purpose of the Program is to act as an information
system, providing archival researchers with the information and
training necessary to use the publicly available EUVE data sets. The
GI Program offers the research community the technical experience and
intricate knowledge of the EUVE data residing at CEA and is open to
all interested researchers -- astronomers, technologists, engineers,
educators, as well as the general public.
--------------------------------------------------------------
THE DISTANCE TO THE CHAIN A HIGH-VELOCITY CLOUD COMPLEX
B.Y. Welsh, N. Craig, and B. Roberts
To appear in Astronomy & Astrophysics. [CEA publication #683]
We present high-resolution (R ~ 5 km/s) Na I and Ca II interstellar
absorption line spectra observed toward five B stars in the line of
sight to the high-velocity cloud complex Chain A. We have failed to
detect the presence of any high-velocity (V < -100 km/s) interstellar
absorption toward these stars. This null detection enables us to
place a new lower limit on the distance to the Chain A complex of z >=
837 +/- 200 pc, assuming normal gas-phase abundances of Na I and Ca
II. If this distance determination is typical for other high-velocity
clouds, it poses problems for theories that currently argue these
clouds interact with the galactic disk.
--------------------------------------------------------------
MODELLING THE SOFT X-RAY AND EUV EMISSION IN CLASSICAL NOVAE: EUVE
AND ROSAT OBSERVATIONS OF V1974 CYGNI
G.S. Stringfellow and S. Bowyer
To appear in Proceedings of IAU Colloquium 152, "Astrophysics in the
Extreme Ultraviolet", ed. S. Bowyer and R.F. Malina (Dordrecht:
Kluwer), 1996. [CEA publication #684]
We have conducted an extensive analysis of the observability of
Classical Novae with the EUVE Lex/B and Al/Ti/C detectors. Predicted
count rates have been computed using optically thin, isothermal plasma
models for solar and metal-rich compositions, and hot ONeMg white
dwarf model atmospheres. We find EUVE to be quite sensitive to both
the EUV and soft X-ray emission emitted by the underlying hot white
dwarf during novae outbursts, except for the coolest temperatures with
very high intervening hydrogen column density. These results are used
to interpret the emission detected during the EUVE all-sky survey of
Nova Cygni 1992 (=V1974 Cyg), 279-290 days after visual maximum. We
find the best fit to the observed emission from V1974 Cyg arises from
a hot ONeMg white dwarf with surface temperature ~4E5 K and a mass of
~1.2 M_solar, and derive an interstellar hydrogen column density of
~3E21 cm^(-2). Virtually all this emission arises from supersoft
X-rays rather than the EUV. We also report the detection of V1974 Cyg
with the EUVE Deep Survey detector at 549 days after visual maximum.
This observation is compatible with the above properties, indicating
that the mechanism responsible for the soft X-ray emission, connected
with the underlying white dwarf, had not yet entirely turned off. We
also present analysis of a ROSAT PSPC observation which is
contemporaneous with the EUVE survey observations; this independently
confirms the high column density we derived from the EUVE survey
observation. Light curves for the EUVE and ROSAT observations are
presented. Statistical tests for variability show that all of these
observations are indeed highly variable over various time scales. The
EUVE survey data shows one day variations, the EUVE DS data show ~30
minute fluctuations, while the ROSAT data vary rapidly on time scales
of seconds. The EUVE data shows no periodic variability on any time
scale. The implications of the rapid variability are briefly
discussed.
--------------------------------------------------------------
NEW INSIGHTS ON THE INTERSTELLAR MEDIUM FROM EUV OBSERVATIONS
S. Bowyer
To appear in Proceedings of IAU Colloquium 152, "Astrophysics in the
Extreme Ultraviolet", ed. S. Bowyer and R.F. Malina (Dordrecht:
Kluwer), 1996. [CEA publication #685]
Observations in the EUV band have provided new insights into the
interstellar medium. In the following I discuss two areas in which
EUV observations are providing unique information: the ionization
state of the ISM, and the pressure of the hot phase of the local
interstellar medium and the bearing of this work on the McKee-Ostriker
model of the ISM.
--------------------------------------------------------------
AN INSTRUMENT TO STUDY THE DIFFUSE EUV ASTRONOMICAL BACKGROUND
S. Bowyer, J. Edelstein, M. Lampton, L. Morales, J. Perez Mercader,
and A. Gimenez
To appear in Proceedings of IAU Colloquium 152, "Astrophysics in the
Extreme Ultraviolet", ed. S. Bowyer and R.F. Malina (Dordrecht:
Kluwer), 1996. [CEA publication #686]
The extreme ultraviolet (EUV) diffuse background is the most poorly
known of any of the diffuse astronomical backgrounds. Only upper
limits to this flux exist, obtained with spectrometers with very crude
(from ~15 to 30 A) resolution; these limits are generally one to two
orders of magnitude larger than the expected sources of cosmic flux. A
variety of source mechanisms have been postulated to radiate in this
bandpass; the most discussed is the hot phase of the interstellar
medium. A speculative possibility is that hot dark matter in the form
of massive, radiatively unstable neutrinos in our Galaxy will produce
a unique line in this bandpass. We describe an instrument employing a
new type of spectrometer which will provide ~5 A resolution and
unprecedented sensitivity for diffuse EUV radiation. The instrument
will be carried aboard the newly developed Spanish Minisat satellite.
--------------------------------------------------------------
EQUILIBRIUM ABUNDANCES OF HEAVY ELEMENTS SUPPORTED BY RADIATIVE
LEVITATION IN THE ATMOSPHERES OF HOT DA WHITE DWARFS,
P. Chayer, S. Vennes, A.K. Pradhan, P. Thejll, A. Beauchamp,
G. Fontaine, and F. Wesemael
To appear in Proceedings of IAU Colloquium 152, "Astrophysics in the
Extreme Ultraviolet", ed. S. Bowyer and R.F. Malina (Dordrecht:
Kluwer), 1996. [CEA publication #687]
We present revised estimates of the equilibrium abundances of heavy
elements supported by radiative levitation in the atmospheres of hot
DA white dwarfs. We emphasize, in particular, the role of trace
pollutants that may be present in the background plasma, an effect
which has been heretofore neglected. We take advantage of the
availability of a table of detailed monochromatic opacities calculated
for a plasma made of H containing small amounts of C, N, O, and Fe to
illustrate how the equilibrium abundances of levitating elements react
to the flux redistribution caused by the addition of these small
traces of opaque material. We also consider two other improvements: a
more sophisticated treatment of the momentum redistribution process
and ion experiences following a photoexcitation, and use of an
upgraded value for the line profile width associated with pressure
broadening.
--------------------------------------------------------------
EUV CONSTRAINTS ON MODELS OF LOW MASS X-RAY BINARIES
D.J. Christian, J.E. Edelstein, M. Mathioudakis, K. McDonald, and M.M. Sirk
To appear in Proceedings of IAU Colloquium 152, "Astrophysics in the
Extreme Ultraviolet", ed. S. Bowyer and R.F. Malina (Dordrecht:
Kluwer), 1996. [CEA publication #688]
We present EUVE survey results for moderate column directions
containing known low-mass X-ray binaries (LMXB). We derive Lexan band
(100 A) count rates and upper limits for nearly 40 LMXB chosen
generally with E_(B-V) <= 0.3. Detections include Sco X-1, Her X-1,
and the GRO transient CJ0422+32. Super soft sources in the LMC yield 3
sigma upper limits of <= 10 counts/ks. The extrapolation of two
component spectral models (such as blackbody plus thermal
bremsstrahlung), are in agreement with the survey upper limits.
Contemporary LMXB spectral models, which involve Comptonization in an
inner disk corona, predict a large flux of EUV photons. If the above
model is correct in the EUV, such a component could be detected in
source with low column densities. We argue that additional intrasystem
column hampers its detection.
--------------------------------------------------------------
THE EUVE OPTICAL IDENTIFICATION CAMPAIGN II: LATE-TYPE AND WHITE DWARF
STARS
N. Craig, A. Fruscione, J. Dupuis, M. Mathioudakis, J. J. Drake, M.
Abbott, C. Christian, R. Green, T. Boroson, and S. B. Howell
To appear in Proceedings of IAU Colloquium 152, "Astrophysics in the
Extreme Ultraviolet", ed. S. Bowyer and R.F. Malina (Dordrecht:
Kluwer), 1996. [CEA publication #689]
We present optical identifications of nine previously unidentified
extreme ultraviolet (EUV) sources discovered during the Extreme
Ultraviolet Explorer (EUVE) satellite surveys. The all-sky survey
detected four of the sources and the more sensitive deep survey
detected the other five sources. Three of the four all-sky survey
sources, EUVE_J1918+59.9, EUVE_J2249+58.5, and EUVE_J2329+41.4, are
listed in present catalogs as having possible associations with
optical counterparts but without spectral class. The first two of
these sources are hot DA white dwarfs showing an optical spectrum with
broad Balmer lines. The source EUVE_J2329+41.4 is listed as having a
possible association with an unclassified M star. We show that a pair
of dMe stars are actually optical counterparts located within the
error circle of the EUVE source position. The EUVE_J2114+503 remains
unidentified even though all the possible candidates have been
studied. Based on the count rates we predict a fainter white dwarf or
a cataclysmic variable counterpart for this candidate. All five
sources discovered with the EUVE deep survey, EUVE_J0318+184,
EUVE_J0419+217, EUVE_J2053-175, EUVE_J2056-171 and EUVE_J2233-096,
have been identified as late-type stars. The spectral classes,
distances, visual magnitudes, and estimated hydrogen column densities
for these EUVE sources are presented.
--------------------------------------------------------------
EUVE AND VLA OBSERVATIONS OF THE ECLIPSING PRE-CATACLYSMIC VARIABLE
V471 TAURI
S.L. Cully, J. Dupuis, T. Rodriguez-Bell, G. Basri, O.H.W. Siegmund,
J. Lim, and S.M. White
To appear in Proceedings of IAU Colloquium 152, "Astrophysics in the
Extreme Ultraviolet", ed. S. Bowyer and R.F. Malina (Dordrecht:
Kluwer), 1996. [CEA publication #690]
We present observations of the eclipsing binary V471 Tauri by the
Extreme Ultraviolet Explorer (EUVE) and the Very Large Array (VLA).
The EUV spectrum is dominated by the continuum of the hot white dwarf
and the time-averaged spectrum is fitted by a (33.1 +/- 0.5)E3 K pure
hydrogen white dwarf atmosphere assuming log g = 8.5. An ISM hydrogen
column density of (1.5 +/- 0.4)E18 cm^(-2) is required to explain the
attenuation of the white dwarf spectrum thus setting the H I column in
the line of sight of the Hyades cluster. The He II lambda 304 A line
is in emission and varies over the orbital period of V471 Tauri
following a sinusoidal modulation with the maximum reached when the K
star is at inferior conjunction. Transient dips are detected at
orbital phase -0.12 in the SW and MW spectrometers integrated
lightcurves but are notably absent in the LW lightcurve indicating the
occulting material is ionized. The VLA observation suggest the
presence of a K star coronal magnetic loop between the two stars
reconnecting with the white dwarf magnetic field. Such a structure
could be the occulting source needed to explain the dips seen in the
lightcurves of V471 Tauri in the EUV.
--------------------------------------------------------------
THE HOT WHITE DWARF POPULATION IN THE EUVE SURVEY
S. Vennes
To appear in Proceedings of IAU Colloquium 152, Astrophysics in the
Extreme Ultraviolet, ed. S. Bowyer and R.F. Malina (Dordrecht:
Kluwer), 1996. [CEA publication #691]
The processes leading to the formation of white dwarf stars are
known only in their most general principles; post-asymptotic giant
branch evolution, leading to the formation of C-O degenerate cores, is
possibly the main formation channel of white dwarf stars. In contrast,
observations of hot white dwarf stars and studies of their main
population characteristics offer detailed insights into the origin and
evolution of these objects. We examine some new facts uncovered in the
study of the survey of hot white dwarf stars at extreme ultraviolet
(EUV) wavelengths. We describe model atmosphere techniques required to
interpret these observations and discuss some implications of our
findings for stellar evolution theory.
--------------------------------------------------------------
A SPECTROSCOPIC SURVEY IN THE EUV OF THE "COOLEST" HOT DA STARS
J. Dupuis and S. Vennes
To appear in Proceedings of IAU Colloquium 152, Astrophysics in the
Extreme Ultraviolet, ed. S. Bowyer and R.F. Malina (Dordrecht:
Kluwer), 1996. [CEA publication #692]
We present an analysis of the extreme ultraviolet (EUV)
spectroscopy of a sample of 10 DA white dwarfs observed by the Extreme
Ultraviolet Explorer (EUVE). We have selected white dwarfs cooler than
about 50,000 K and with presumably low heavy element abundances. The
goal of this study is to determine the fundamental atmospheric
parameters, namely the effective temperature and chemical composition,
of these stars by fitting their continua with synthetic spectra
computed from pure hydrogen LTE/line-blanketed model atmospheres. The
question of the presence (or absence) of trace elements is explored by
comparing EUV-determined effective temperatures to the one obtained
from a fit of hydrogen balmer lines. It is found that the majority of
the DA in the sample are consistent with having a pure hydrogen
atmosphere. One of the stars, MCT 0027-634, is another possible
example of a HZ 43-type white dwarf, having an effective temperature
above 50000 K and a low heavy element abundance, i.e., much lower than
predicted by diffusion theory.
--------------------------------------------------------------
EUV AND SOFT X-RAY EVIDENCE FOR PARTIALLY IONIZED GAS IN ACTIVE
GALACTIC NUCLEI
J.P.D. Mittaz, R. Lieu, S. Bowyer, C.-Y. Hwang, and J. Lewis
To appear in Proceedings of IAU Colloquium 152, Astrophysics in the
Extreme Ultraviolet, ed. S. Bowyer and R.F. Malina (Dordrecht:
Kluwer), 1996. [CEA publication #693]
We present a synoptic study of active galactic nuclei (AGN)
detected by EUVE. We also present complementary ROSAT PSPC spectra for
these sources and for other AGN in directions of low galactic
absorption. It is found that the best-fit power-law photon indices of
the X-ray spectra at 0.1-2.4 keV are anti-correlated with their
galactic hydrogen columns. The indices for the 0.9-2.4 keV range do
not show such a correlation, and are considerably smaller (i.e.
flatter). We discuss a number of possible interpretations of this
correlation but only one of these, the presence of a partially ionized
absorbing gas in the AGN, explains the observations satisfactorily.
The ubiquity of this effect suggests that this component be may very
common in AGN.
--------------------------------------------------------------
AN OPTICAL STUDY OF THE FIELD OF EUVE J1027+323: DISCOVERY OF A QSO
AND A HIDDEN HOT WHITE DWARF
R. Genova, S. Bowyer, S. Vennes, R. Lieu, J.P. Henry, J.E. Beckman,
and I. Gioia
To appear in Proceedings of IAU Colloquium 152, Astrophysics in the
Extreme Ultraviolet, ed. S. Bowyer and R.F. Malina (Dordrecht:
Kluwer), 1996. [CEA publication #694]
We have carried out optical and Far UV studies of the field around
the EUV source EUVE J1027+323. We find two sources which contribute
to this flux which are spatially unresolvable with EUVE. One is a
non-cataloged QSO and one is a "hidden" hot white dwarf. (Based in
part on observations obtained at the Michigan-Dartmouth-MIT
Observatory.) Reasonable scenarios ascribe the majority of the flux
to the white dwarf.
--------------------------------------------------------------
EUVE OBSERVATIONS OF THE SEYFERT GALAXY MRK 279
C.-Y. Hwang, S. Bowyer, and M. Lampton
To appear in Proceedings of IAU Colloquium 152, Astrophysics in the
Extreme Ultraviolet, ed. S. Bowyer and R.F. Malina (Dordrecht:
Kluwer), 1996. [CEA publication #695]
We report EUVE spectral and photometric data of the Seyfert 1
galaxy MRK 279. The photometric data show large amplitude variations
over time scales less than 10,000 s. The spectrum is characterized by
several features between 80 and 100 A. We compare the observed data
with several models. We can rule out the possibility that the EUV
emission is from a diffuse corona or intercloud medium. Models that
assume the soft X-ray/EUV emission results from reprocessing in an
optical BLR region are also inconsistent with the data. A collisional
excitation model is consistent with the observations but requires a
cloud density >= 1E11 cm^(-3).
--------------------------------------------------------------
SEARCHING EUVE DATA FOR TRANSIENT/FLARING EXTREME ULTRAVIOLET SOURCES
J. Lewis, S. Bowyer, M. Lampton, X. Wu, and M. Mathioudakis
To appear in Proceedings of IAU Colloquium 152, Astrophysics in the
Extreme Ultraviolet, ed. S. Bowyer and R.F. Malina (Dordrecht:
Kluwer), 1996. [CEA publication #696]
The Extreme Ultraviolet Explorer (EUVE), because of its sky survey
strategy, performed two observations of each point along a 180 deg by
1 deg strip of the ecliptic during the initial survey phase of the
mission. One observation used the deep survey telescope, and another,
90 days earlier or later, used the all sky scanner telescopes, two of
which have a nearly identical passband to that of the ecliptic deep
survey. Since the completion of the initial sky survey, EUVE has been
used to carry out deep, pointed observations of selected targets. Many
areas of the sky have therefore been observed two or more times,
allowing us to compare count rates for some objects over a long
temporal baseline. Objects with significantly varying count rates for
widely separated times are of particular astrophysical interest.
With this technique, we have discovered one such object, which
appears in the First EUVE Source Catalog as EUVE J2056-171. We present
upper and lower limits on how frequently other highly-variable objects
will be detected by EUVE in future observations.
--------------------------------------------------------------
DISCOVERY OF WARM GAS IN THE VIRGO CLUSTER
R. Lieu, J.P.D. Mittaz, S. Bowyer, J.H.M.M. Schmitt, and J. Lewis
To appear in Proceedings of IAU Colloquium 152, Astrophysics in the
Extreme Ultraviolet, ed. S. Bowyer and R.F. Malina (Dordrecht:
Kluwer), 1996. [CEA publication #697]
During the EUVE sky survey of the Virgo region, a central source
positionally coincident with the X-ray emitting galaxy M87, and a
surrounding halo of extended emission, were detected in the
0.065-0.248 keV band. A detailed comparison of these data with the
ROSAT PSPC data of M87 revealed an excess flux at energies < 0.4 keV
within the central 30 arcmin radius which cannot be associated with
the well-known cluster gas at X-ray temperatures (kT >= a few keV).
Instead, it is necessary to introduce a second gas component, of
temperature T ~ 5E6 K (kT ~ 0.1 keV). The resulting two-component
model (warm + hot) can account for all the data. The origin and
stability of the warm component, with a temperature near the peak of
the thermal plasma cooling curve, is unclear. Both the temperature
and spatial extent argue against cooling flow as the primary process
responsible for its production. Other mechanisms, such as a galactic
wind and heating by galaxy motions, must be considered.
--------------------------------------------------------------
THE SECRETS OF EUVE J2056-17.1
M. Mathioudakis, J.J. Drake, N. Craig, D. Kilkenny, J.G. Doyle, M.
Sirk, J. Dupuis, A. Fruscione, C.A. Christian, and M.J. Abbott
To appear in Proceedings of IAU Colloquium 152, Astrophysics in the
Extreme Ultraviolet, ed. S. Bowyer and R.F. Malina (Dordrecht:
Kluwer), 1996. [CEA publication #698]
EUVE J2056-17.1 is one of the brightest sources in the First EUVE
Source Catalog with 0.24 counts/s in the Deep Survey Lexan/B band. We
present optical and EUV results that show this source is one of the
most active late-type dwarfs. EUVE observed a large flare with energy
in excess of 1E35 ergs in its Lexan/B band. The quiescent optical
spectrum of the source reveals strong hydrogen Balmer and Ca II H and
K emission. A strong Li I 6707 A line is also present in the spectrum.
We have estimated a Li abundance of log N(Li) = 2.5 +/- 0.4. The high
Li abundance and the high flare activity favors an interpretation
where the enhanced Li is sustained by spallation reactions.
--------------------------------------------------------------
THE THREE-DIMENSIONAL STRUCTURE OF EUV ACCRETION REGIONS OF AM HER
STARS: ANALYSIS OF EUVE LIGHT CURVES
M.M. Sirk and S.B. Howell
To appear in Proceedings of IAU Colloquium 152, Astrophysics in the
Extreme Ultraviolet, ed. S. Bowyer and R.F. Malina (Dordrecht:
Kluwer), 1996. [CEA publication #699]
We present EUV light curves for a number of AM Her systems observed
either as GO targets or with the EUVE Right Angle Program. We have
formed light curves for eight AM Her stars and show in our
presentation the similarities and differences present. We draw some
conclusions by grouping the systems by inclination, magnetic field
strength, and accretion region geometry. In order to understand the
physical structures responsible for the EUV emissions, we have
developed a software model to generate synthetic light curves. We find
that the EUV accretion regions in the systems UZ For, VV Pup, and AM
Her cannot be fit with a flat spot confined to the white dwarf
surface, regardless of its shape or brightness profile. Rather, a
small, symmetric, raised spot is the only shape consistent with the
data. The light curves for systems EF Eri, RE1149+28, AN UMa, and V834
Cen show evidence for additional structure that precedes the primary
accretion region in phase. Our model indicates that a large portion of
the light curve in each system is seen in absorption. Finally, in
three systems, we detect a very gradual rise and fall in the EUV flux
(<5% of the peak flux) at phases when the spot is completely obscured
behind the white dwarf (WD) limb. We attribute this detection to
emission from the accretion column that decreases exponentially with
distance from the WD and detect emission at heights up to 15% of the
WD radius.
--------------------------------------------------------------
EXTREME ULTRAVIOLET SPECTROSCOPY OF THE SEYFERT 1 GALAXY MARKARIAN 478
D.A. Liedahl, F. Paerels, M.Y. Hur, S.M. Kahn, A. Fruscione, and S.
Bowyer
To appear in Proceedings of IAU Colloquium 152, Astrophysics in the
Extreme Ultraviolet, ed. S. Bowyer and R.F. Malina (Dordrecht:
Kluwer), 1996. [CEA publication #700]
The Seyfert 1 galaxy Mrk 478, observed during the EUVE all-sky
survey, is the brightest EUV source among its class. The SW spectrum
of this object shows evidence of discrete emission, although this
interpretation is tentative, since the source spectrum must be
extracted against a bright background. If the EUV flux is, in fact,
composed partly of line emission, we consider the implications if this
is the result of emission from a collision-driven plasma at
temperatures ~> 1E6 K. In this context, we discuss some of the
constraints imposed on the emission-line region by this observation.
--------------------------------------------------------------
EUVE AND ORFEUS OBSERVATIONS OF THE COOL DO WHITE DWARF HD 149499 B
R. Napiwotzki, S. Jordan, S. Bowyer, M. Hurwitz, D. Koester, T. Rauch,
and V. Weidemann
To appear in Proceedings of IAU Colloquium 152, Astrophysics in the
Extreme Ultraviolet, ed. S. Bowyer and R.F. Malina (Dordrecht:
Kluwer), 1996. [CEA publication #701]
We present the results of a recent spectroscopic investigation of
the cool DO white dwarf HD 149499 B in the EUV and FUV ranges.
Observations were performed with the spectrograph of the EUVE
satellite and the Berkeley EUV/FUV spectrometer of the ORFEUS space
experiment. (Based on the development and utilization of ORFEUS --
Orbiting and Retrievable Far and Extreme Ultraviolet Spectrometers, a
collaboration of the Astronomical Institute of the University of
Tuebingen, the Space Astrophysics Group, University of California,
Berkeley, and the Landessternwarte Heidelberg.) The analysis of the
ORFEUS spectrum, performed with a grid of LTE model atmospheres,
yielded the basic parameters T_eff = 49500 +/- 500 K and log g = 7.97
+/- 0.08. This result is confirmed by the EUVE spectra. The
photospheric hydrogen Lyman lines in the FUV spectrum indicate the
presence of hydrogen: log n_H/n_He = -0.65 +/- 0.12. The implications
of this finding for the spectral evolution of white dwarfs are
discussed. A check of the LTE assumption was performed by a
comparison with NLTE atmospheres calculated for appropriate
parameters. The interstellar hydrogen column towards the HD 149499
system amounts to N(H) = (7 +/- 2)E18 cm^(-2).
--------------------------------------------------------------
EXTREME ULTRAVIOLET EMISSION FROM NEUTRON STARS
R.S. Foster, J. Edelstein, and S. Bowyer
To appear in Proceedings of IAU Colloquium 152, Astrophysics in the
Extreme Ultraviolet, ed. S. Bowyer and R.F. Malina (Dordrecht:
Kluwer), 1996. [CEA publication #702]
We summarize the detections of extreme ultraviolet (EUV) emission
from neutron stars. Three firm detections have been made of
spin-powered pulsars: the aged millisecond pulsar PSR J0437-4715, the
middle-aged X-ray pulsar Geminga, and the radio pulsar PSR B0656+14.
These observations allow us to evaluate both power-law and thermal-law
emission models as the source of the EUV flux. For the case of PSR
B0656+14 the lack of flux modulation with pulse period argues that the
EUV radiation originates from the cooling neutron star surface rather
than from a hot polar cap. If the emission is from a thermalized
neutron star surface, then limits can be placed on the surface
temperature. For the case of Geminga we can explain the observed EUV
flux using thermal models that are consistent with standard neutron
cooling scenarios. We also have a weak indication that the EUV
emission from Geminga is pulsed in a manner consistent with the lowest
energy channel observed with ROSAT. For the case of the millisecond
pulsar PSR J0437-4715 standard neutron star cooling models require
surface re-heating. We compare different heating models to the data on
this object. We rule out re-heating by crust-core friction, and find
that models for the accretion from the interstellar medium, accretion
from the white dwarf companion and a particle-wind nebula do not
account for the EUV luminosity. Models of pulsar re-heating by
magnetic monopole catalysis of nucleon decay are used to establish new
limits to the flux of monopoles in the Galaxy. A single power-law
source with properties derived from X-ray data cannot explain the EUV
flux from PSR J0437-4715. The strongest model for explaining the EUV
emission consists of a large ~3 km^2 polar cap heated from particle
production in the pulsar magnetic field. We consider the prospects
for detecting other neutron stars in the extreme ultraviolet.
--------------------------------------------------------------
2. Science Operations News
==========================
2.1 Cycle 4 GO Proposal Summary
-------------------------------
by Dr. Damian Christian, GO Scientist, ISO Science Support Team
In response to the NASA Research Announcement for Cycle 4 EUVE GO
observations, a total of 77 proposals have been submitted to the EUVE
Project Office. The proposals break down into the following
categories:
Number Category
------ -------------------------
13 Early- and Late-Type Stars
13 Extragalactic Objects
12 Other Binary Systems (RSCVn, Symbiotic Stars, etc)
11 Post-Main Sequence Stars and Collapsed Objects
8 Binary Systems (CVs)
4 Solar System Objects
3 ISM and Galactic Structure
13 Other or Not Classified
Technical review of the proposals is currently underway at CEA. The
peer review process will be held 5-6 Dec, with the announcement of the
results in mid-Jan 1996. Observing for Cycle 4 is scheduled to begin
in Mar 1996.
2.2 Public Data Release for 1 Dec 1995
--------------------------------------
by Dr. Nahide Craig, Archive Scientist, ISO Science Support Team
The table below lists the GO observations that become public on 1
Dec 1995. For each entry is given the target name, the approximate
exposure time in ksec, the GMT start and end date(s) for the
observation, the spectral type of the target, and the data
identification code. All public data sets can be ordered from the
archive via WWW and electronic or postal mail (see addresses below).
Please be sure to include in your order the DataID(s) of interest.
Processed data sets are shipped on 8mm tape (or, if requested, on
CD-ROM) via postal mail.
The data rights policy for GO observations states that GOs have
proprietary rights to the data for one year from the date (s)he
receives it. It is often the case that long observations are broken
up over many months; e.g., an observation approved for 60 ksec may
actually be observed for 10 ksec one month, 20 ksec the next and 30
ksec three months later. In such cases the one-year proprietary
period begins after the GO is sent the final piece of the completed
observation.
===============================================================
Target ~Exp Observation Date(s) SpT DataID
Name (ksec) Start End
===============================================================
Data Sets Available 1 Dec 1995:
GD_246 39 16 Jul - 17 Jul 1994 DA go0235
GD_246 13 08 Aug - 08 Aug 1994 DA go0236
JUPITER 87 03 Jul - 06 Jul 1994 SolSys go0237
JUPITER 81 13 Jul - 16 Jul 1994 SolSys go0238
JUPITER 69 17 Jul - 20 Jul 1994 SolSys go0239
JUPITER 100 20 Jul - 23 Jul 1994 SolSys go0240
JUPITER 78 23 Jul - 26 Jul 1994 SolSys go0241
JUPITER 54 29 Jul - 30 Jul 1994 SolSys go0242
JUPITER 100 08 Aug - 12 Aug 1994 SolSys go0243
JUPITER 4 12 Aug - 12 Aug 1994 SolSys go0244
GD_659 100 23 Sep - 27 Sep 1994 DA go0245
GD_659 84 27 Sep - 30 Sep 1994 DA go0246
GD_659 5 30 Sep - 30 Sep 1994 DA go0247
===============================================================
2.3 New IRAF/EUV and EGODATA Releases
-------------------------------------
by Dr. Mark Abbott, EUVE Scientist, Information Systems
Development Group
The EUVE GO (EGO) Center announces the release of new versions of
the EUV layered package for IRAF and of the EGODATA calibration data
set. Although these releases primarily implement changes to the batch
processing of observations at the EGO Center, they may contain items
of interest to users (e.g., see the section below on changes to the
delivered data products).
The EGO documentation products -- the Data Products Guide and
Software User's Guide -- do not yet reflect the changes described
below. In the near future the EGO Center will release either revised
versions of those documents or addenda to the existing versions. The
on-line help for individual tasks in the IRAF/EUV package is up to
date and should be considered more reliable where it conflicts with
older documentation.
Version 1.6 of the IRAF/EUV package and version 1.11 of the EGODATA
reference data set may be obtained from the CEA WWW
(http://www.cea.berkeley.edu/) or anonymous ftp (ftp.cea.berkeley.edu)
sites.
Please direct all questions or comments to egoinfo@cea.berkeley.edu.
Software Changes
EUV 1.6 contains the following five new tasks:
o dscen -- Robustly computes the centroid of the image of a source in
the Deep Survey (DS) detector. While users may wish to run
dscen, it is primarily intended for use within the EGO Center
batch processing system.
o qpdup -- A simple QPOE copying task (similar to, but simpler to use
than, the PROS task qpcopy) that is useful for copying a QPOE
file while applying attribute filters.
o detpos -- Computes the position on one of the EUVE imaging
detectors at which a particular point on the sky is imaged
versus time during an observation. It is meant to be used in
conjunction with the tasks effexp and masktimes.
o effexp -- Computes the effective exposure time during an EUVE
observation. It corrects the exposure time for the effects of
primbsching and deadtime. When used with the output from the
new task detpos for EUVE imaging data, effexp will also correct
for vignetting and can eliminate time spent in bad regions of
the detector. Effexp can also be used in conjunction with the
PROS task ltcurv to produce effective exposure times for light
curves of spectrometer or imaging data.
o masktimes -- Computes the time intervals during which a source was
in or out of specific detector regions, based on the output of
the new task detpos.
The parameters for the existing tasks backmon and mkprimbsch have
also changed slightly. See the release notes that accompany the
software for a full description of the changes.
Calibration Data Changes
EGODATA 1.11 contains several new or changed files, including
improved vignetting maps and effective areas for the DS and scanner
instruments. There has been no change to calibration data affecting
spectrometer observations.
Changes to Delivered Data Products
There have been three substantial changes in the way data is
processed at the EGO Center of which GOs should be aware.
New source position algorithm
Where possible, spectrometer observations are now remapped
(using the task cep) with a source position that has been
determined from the DS image of the source rather than with the
GO-supplied source position. This reduces two long-standing
sources of systematic error: incorrect source coordinates supplied
by GOs and boresight errors in the calibration (possibly due in
part to telescope flexure).
The effect of the these two errors is the same -- spectra are
shifted by unknown and varying amounts in both wavelength and
imaging angle in each spectrometer. Usually these effects are
small, but occasionally a source would show a large shift, such
that the automated spectral extraction performed at the GO Center
would miss all or almost all of the spectrum.
A solution to these errors has been publicized by the EGO
Center for some time: rerun the pipeline (cep) using the source
position measured from the remapped DS Lexan image of the source
made during the observation. This would cancel any boresight
errors and remove the possibility of an incorrect source position
at the same time. We now will be using this technique in the
automated processing at the EGO Center. The DS data is reduced
first, the new task dscen is used to compute the centroid of the
image of the source in equatorial coordinates, and then this
position is used to reduce the spectrometer data. The procedure
is performed very conservatively -- if the DS position is not well
determined, or if the new position is unduly far from the
GO-supplied source position, then we revert to using the original
position. The goal is to make improvements where possible, but
never to make things worse.
The new procedure is not attempted for moving targets such as
the Moon, Jupiter, or comets. It also is not useful with any
source that has a DS Lexan image too faint to centroid accurately.
Such targets will be reduced using the GO-suppled source position.
IMPORTANT: This improvement in the automated processing at the EGO
Center will help to reduce the incidence of extremely poorly
extracted quick-look spectra being delivered to GOs. But the
extracted spectra are still far from optimal in many cases. As
always, GOs are still strongly urged to always carefully inspect
their 2-d spectral images and to perform their own extraction of
the spectra to get the best signal-to-noise.
Trimmed event lists
To help reduce the volume of data GOs must keep online while
reducing their EUVE data, we are now delivering trimmed event
lists. The EUVE QPOE files for the spectrometers now contain only
events with a Y position between 720 and 1299. This provides a
broad strip with sufficient area above and below the spectrum for
background subtraction, and eliminates the less useful areas near
the top and bottom edges of the spectrometers, especially the
unused alternate filters at the bottom of the medium- (MW) and
long-wavelength (LW) spectrometers. Such trimming typically
reduces the size of QPOE files by a factor of two.
IMPORTANT: These events are trimmed from the QPOE file during
automated processing using the new task qpdup after the pipeline
task cep has been run. All of the events from each spectrometer
are still delivered to GOs as part of the raw event list
(table0.tab). So any GOs who wish to analyze these trimmed
regions of the data need only rerun the pipeline on their raw data
tables to recover full QPOE files. Note that this is NOT true for
the DS data that is delivered to GOs. DS events in the
Aluminum/Carbon quadrants at the top and bottom of the detector
(which have very bright background) are eliminated early in the
processing and are not present in the raw event list; therefore
they are not accessible to GOs.
New earth blockage angle
For some time now, the EGO Center has been using a time filter
that accounts for both detector on/off periods and those of
earth-blockage to determine spectrometer exposure times. However
the EGO Center has been using a more conservative definition of
earth blockage (i.e., eliminating more time) than is used when
planning EUVE observations. The result is that, for some
observations, it appeared that GOs were being delivered less than
their full dataset, when in fact this was not true.
To eliminate this confusion, the EGO Center is now processing
with the same numbers as are used for observation planning. The
maximum valid DS/Spectrometer Zenith Angle has been raised from
97.93 degrees to 107.41 degrees. This means that more time near
the limb of the earth is being counted as valid exposure. There
has been no change in the actual event lists that are delivered.
GOs who wish to continue to use the old angle (or any other angle)
should reconstruct images from their event lists using their own
filters. The angle used by the EGO Center should not be
considered necessarily optimal for analysis of EUVE data,
especially in the MW and LW spectrometers.
2.4 EUVE Enters Safe-Hold Mode for First Time
---------------------------------------------
by Brett Stroozas, ISO Manager
On 17 Oct the EUVE spacecraft entered Safe-Hold mode for the first
time. Because there have been some anomalous readings in the past
from one of the Attitude Control System's (ACS) gyroscopes, the Flight
Operations Team (FOT) at GSFC was reconfiguring the gyros to move this
particular gyro out of the primary operations loop and into a backup
capacity. After making this switch the ACS was reinitialized to
update its calibration values. When coupled with a comparison of
readings of the Earth's magnetic field to those of a model, these
calibration values allow the ACS to determine an initial estimate of
the satellite attitude. Unfortunately, the magnetic field model is
only valid when the satellite is positioned on the Sun-line, which was
not the case (EUVE was pointed ~30 degrees off the Sun-line). As a
result, the ACS was not able to determine where it was so the on-board
Fault Detection/Correction logic placed EUVE into Safe-Point mode
(i.e., realigned the satellite to the sun-line). EUVE has been in
Safe-Point mode on a few occasions in the past.
However, due to the nature of the situation, the process of
recovering from Safe-Point mode took longer than it has in the past.
During this time the satellite was in Digital Fine Sun Sensor
acquisition mode (i.e., locking onto the Sun) when it transitioned
into the night portion of its orbit. When this happened, the on-board
software interpreted the loss of the Sun as a hardware failure, and
put EUVE in Safe-Hold mode. The recovery back to normal operations
took a little over a day.
The final results of this anomaly were both positive and negative.
On the negative side, EUVE lost some science data as it was necessary
to cancel and reschedule the calibration observation of G191-B2B; the
following observation of EUVE J0922+710 was conducted as scheduled.
On the positive side, this was the first "test" of Safe-Hold mode and
everything worked as expected (an actual on-orbit Safe-Hold test had
never been approved due to the potential problems in turning things
back on once they had been turned off). Another positive note was
that the automated telemetry monitoring software in the EUVE Science
Operations Center (ESOC) performed as expected, detecting the anomaly
and paging appropriate CEA personnel.
2.5 1:0 Transition in the ESOC
------------------------------
by Brett A. Stroozas, ISO Manager
Since the completion of the three-shift to one-shift (3:1)
transition in early 1995, the ESOC at CEA has only been staffed by
payload controllers during a single shift, seven days/week, instead of
the three shift, 24 hour/day, seven days/week coverage that we've
employed in the past. This transition was made possible by the
implementation in the ESOC of automated software that monitors the
incoming EUVE science payload telemetry; in the case of an anomaly,
the software pages an on-call controller who immediately responds to
deal with the situation.
Because of the success of 3:1, ISO has been working on plans for a
one-shift to zero-shift (1:0) transition in the ESOC. Building on the
previous 3:1 work, the 1:0 plans provide a phased approach into a
zero-shift environment in which all routine daily telemetry monitoring
and the associated support tasks are automated. In Phase 1 --
"minimal" zero shift (scheduled for 15 Nov 1995), all essential
payload health and safety telemetry monitoring will be handled
autonomously. In Phase 2 -- "operational" zero shift (scheduled for
Spring 1996), all of the supporting telemetry review, ground system
monitoring, and routine commanding tasks will be automated. An
intermediate Phase 1.5 -- "semi-operational" zero shift (scheduled for
15 Dec 1995) -- will implement a subset of the Phase 2 functionality
in order to provide us with a near-term goal to drive the development
efforts, with a sufficient time period within which to validate the
software and simulate zero-shift operations prior to Phase 2, and with
a means to incrementally reduce the amount of human interaction during
the single weekday/weekend shift.
An internal CEA review of the 1:0 plans was held on 13 Oct. The
review committee approved the plans and recommended making the
transition as scheduled subject to GSFC approval. A GSFC review of
the 1:0 plans, attended by various EUVE Project representatives, was
held via telecon on 13 Nov. The review panel approved the Phase 1
transition plans and the transition was made on 15 Nov. In regards to
Phases 1.5/2, the panel requested additional information that is
currently being compiled and will be forwarded to them in early Dec.
A follow-up telecon will be held ~11 Dec seeking final approval for
the Phase 1.5/2 transitions.
2.6 Recent Newsletter "Bouncing" Problem
----------------------------------------
by Brett Stroozas, ISO Manager
I'd first like to apologize to all those who received multiple
copies of last month's newsletter. Secondly, I'd like to thank those
of you who notified us of the problem and patiently put up with the
resulting multiple messages. After some investigation, the systems
support group at CEA has tracked down and remedied the problem so that
it will (hopefully) not recur in the future.
Apparently, the problem was not at CEA but at a particular remote
site that received the newsletter. The remote site was either trying
to forward the newsletter or to bounce it, but their mail program was
not correctly parsing the mail headers. In affect, it was replying
directly to the list of recipients instead of going through the
euvenews mail exploder, which is set up at CEA to block such
distribution without prior approval from the exploder's owner (i.e.,
me). So, the result was that many persons received multiple copies of
the newsletter.
We have taken corrective steps, both internal to CEA and with the
particular remote site, to ensure that this problem won't happen
again. We apologize again for any inconvenience and thank you for
your patience and understanding.
2.7 EUVE Represented at Telemetering Conference
-----------------------------------------------
by Frank Kronberg, Research Associate, Applied Research
Technology Group
The International Foundation for Telemetering held its 31st Annual
Conference on "Re-engineering Telemetry" on 30 Oct - 02 Nov 1995 at
the Riviera Hotel in Las Vegas, NV.
Annadiana Abedini, CEA Computer Systems Manager, presented "A
Low-Cost, Autonomous, Ground Station Operations Concept and Network
Design for EUVE and Other Earth-Orbiting Satellites" (CEA #667). The
paper reports on an evaluation by CEA and NASA's Jet Propulsion
Laboratory (JPL) of a commercially available ground station already
used for NASA's Low-Earth Orbit (LEO) weather satellites.
Dennis Biroscak, CEA Technical Coordinator for ISO presented
"Re-Engineering EUVE Telemetry Monitoring Operations: A Management
Perspective and Lessons Learned from a Successful Real-World
Implementation" (CEA #669), in which he focused on the management
decisions during the 3:1 transition in the ESOC and how they affected
the cost, schedule, personnel, and technical implementation. Both the
successes and difficulties of the 3:1 transition were presented.
Dennis drew parallels with the current 1:0 transition and showed that
successful practices, such as the continual review of assumptions and
the organization of personnel into teams, were again being utilized.
Frank Kronberg, EUVE Research Associate, presented "Re-Engineering
the EUVE Payload Operations Information Flow Process to Support
Autonomous Monitoring of Payload Telemetry" (CEA #668). The paper
discusses the re-engineering of the documentation in response to the
challenges of single-shift operations and describes the innovations
implemented to accomplish the goals of the re-engineering effort.
The opening session speaker, Dr Jerome Hines (Lt. Gen., USA, Ret.),
a group vice president with Computer Sciences Corporation, detailed
his experience with re-engineering projects both at government
installations and in private enterprise. After considering the work
of Michael Hammer and James Champy, Dr. Hines presented the following
lessons learned from his experience:
(1) MOST IMPORTANT: Top leaders of the organization must be involved
with, and committed to, the re-engineering effort. If they don't
back you with authority, vision, and passion, quit the effort.
(2) WHO: Members of the re-engineering team must be totally
responsible for, and work full-time on, the re-engineering
effort.
(3) WHAT: A powerful vision of the future must be constructed or
generated.
(4) WHY: A compelling case for action must be presented.
(5) HOW: Specific goals of the re-engineering effort must be
delineated and maintained.
Dr. Hines also detailed the following seven steps to change:
(1) Establish the scope of the re-engineering project.
(2) Redesign the solution until all participants sign off on the
plan.
(3) Create a blueprint for the changes.
(4) Construct the transition plan for implementing the goals.
(5) Prototype a model of the results desired.
(6) Successfully institute several pilot projects.
(7) Roll-out the re-engineering project across the entire
organization.
Finally, Dr Hines considered several common themes that run across
most re-engineering projects: partnering, trust, clarity of goals,
mission, empowerment, delegation, maintaining momentum, communication,
customer focus, and future pull. On a number of occasions he
reiterated the importance of communication and customer focus.
Short courses presented at the ITC this year included: Basic
Telemetry Concepts (Norm Lantz), Intermediate Concepts (Jud Strock),
Design of PCM/FM and PCM/PM TM Systems (Dr. Frank Carden), GPS for
Range Applications (Tom MacDonald), and Error Control Coding (Dr.
Michael Rice).
2.8 On-Line Access to EUVE
--------------------------
Listed below are the various methods for on-line access to EUVE:
o CEA World Wide Web (WWW)
URL http://www.cea.berkeley.edu/
telnet www.cea.berkeley.edu 200 (for those without a WWW browser)
o anonymous FTP
ftp ftp.cea.berkeley.edu
Name: anonymous
Password: type_your_full_e-mail_address
o anonymous gopher
gopher ftp.cea.berkeley.edu
o EUVE Electronic Newsletters
Past issues -- available via the CEA WWW site
Subscriptions -- mail majordomo@cea.berkeley.edu ("subscribe
euvenews")
Post message to all subscribers: mail euvenews@cea.berkeley.edu
o GI Program
Are you interested in finding out about or using EUVE data? Do
you need help in understanding EUVE data sets? Do you need help
in using the available EUVE data analysis software tools? If you
answer "yes" to any of the above, the Guest Investigator (GI)
Program at CEA can help YOU! For more information see the CEA
WWW site or contact the Archive (archive@cea.berkeley.edu).
o Public RAP
The Public Right Angle Program (RAP) is an easy method for
researchers to propose for long-exposure EUVE imaging data. For
more information on the Public RAP and the simple proposal
process see the CEA WWW site or contact the EGO Center
(egoinfo@cea.berkeley.edu). Mail all proposals to
euverap@cea.berkeley.edu.
o Contact information for the EUVE Science Archive or GO Center:
Center for EUV Astrophysics
2150 Kittredge St.
Berkeley, CA 94720-5030
Archive EGO Center
510-642-3032 (voice) 510-643-8727 (voice)
510-643-5660 (fax) 510-643-5660 (fax)
archive@cea.berkeley.edu egoinfo@cea.berkeley.edu
3. CEA Job Listings
===================
by Cathie Jones, CEA Personnel Manager
Programmer Analyst II, Job # 09-323-30 (full-time career position)
Serve as a software engineer at the Center for EUV Astrophysics.
Design prototype software systems for low cost automated satellite
operations and human computing. General programming areas will be
supporting Artificial Intelligence (AI) research in
model/rule/constraint-based reasoning as applied to orbiting vehicles
and data acquisition/control loops.
Qualifications include a strong background in Electrical
Engineering, Computer Science, Space Engineering, and/or Information
Systems, with proven software development experience required.
Experience with the design and implementation of AI software, and
orbiting vehicle ground/flight software design required. Experience
in a combination of the following: UNIX (SUN, SGI, HP), C, C++, LISP,
Fortran, and scripting; development of intelligent image processing
systems, fault diagnosis, fuzzy controllers, network algorithms and
protocols, network based parallel computing; product design
experience. CASE tool experience a plus. Experience with WWW
(Netscape, Mosaic), GUI development, windowing systems preferred.
To apply, formal resume must be submitted to:
Personnel Office #3540
Box 09-323-30
2200 University Ave.
Berkeley, CA 94720-3540
---------------------------------------------------------------------------
The EUVE Electronic Newsletter is issued by the Center for Extreme
Ultraviolet Astrophysics, University of California, Berkeley, CA
94720, USA. The opinions expressed are those of the authors. EUVE
Principal Investigators and Newsletter Publishers: Dr. R.F. Malina
and Professor S. Bowyer. ISO Manager and Newsletter Editor: B.A.
Stroozas. Funded by NASA contract NAS5-29298. Send newsletter
correspondence to ceanews@cea.berkeley.edu.
The EUVE project is managed by NASA's GSFC: Paul Pashby, GSFC
Project Manager; Dr. Yoji Kondo, Project Scientist; Dr. Ronald
Oliversen, Deputy Project Scientist; Mr. Kevin Hartnett, Project
Operations Director. NASA HQ: Dr. Robert Stachnik, Program
Scientist; Dr. G. Riegler, Program Manager. Information on the
EUVE GO Program is available from Dr. Y. Kondo, Mail Code 684, GSFC,
Greenbelt, MD 20771 at (301) 286-6247 or e-mail to
euve@stars.span.nasa.gov.
END-----------EUVE------------ELECTRONIC---------------NEWS-------------END
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