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ELECTRONIC NEWSLETTER OF THE EUVE OBSERVATORY
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Vol. 7, No. 3 31 Mar 1997 ISSN 1065-3597
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(C) 1997, Regents of the University of California
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Notes from the Editor
=====================
by Brett A. Stroozas, EUVE Flight Operations Manager
Welcome to the electronic newsletter for NASA's Extreme Ultraviolet
Explorer (EUVE) satellite, compiled and published monthly by 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. EUVE Science News
1.1 Public GO/RAP Data Release for 1 Apr 1997
1.2 Abstracts of Recently *Accepted* EUVE Papers
2. EUVE Satellite Operations News
2.1 UCB-CEA Begins Realtime Operations of EP Spacecraft
2.2 EUVE Target of Opportunity: T Leo
2.3 Extended Survey Period for Spacecraft Calibrations
2.4 UCB-CEA Handles Its First Spacecraft Anomaly
2.5 On-Line Access to EUVE
3. EUVE Outsourced Extended Mission Status Report
3.1 Commencement of Phase 2 "Realtime" Shadow Operations
3.2 Remote Support Site at GSFC SDVF
3.3 EPOC Ground Systems Status
3.4 Performance Criteria Update
To comment on or make suggestions for the EUVE electronic newsletter,
please send e-mail to ceanews@cea.berkeley.edu (Internet).
The EUVE observatory performed well throughout the month of Feb
1997, completing and/or beginning observations of the following Guest
Observer (GO) and Right-Angle Program (RAP) targets. For each target
is listed its name, spectral type, observation start date and time (in
day_of_year:hours_minutes GMT format), name of Principal Investigator
(PI), observation type/priority, and any relevant notes:
=======================================================================
Target SpT Start PI T Notes
=======================================================================
V471 Tau K0 030:00:00 (30 Jan) Siegmund 1 EGO,TCO,COO
A1795 ClGal 034:06:40 (03 Feb) Lieu 1 EGO
gamma Tau K0III 038:02:00 (07 Feb) Stern 2 EGO
Mkn 421 BLLac 038:02:00 (07 Feb) Fruscione 3 RAP
HD 97334 G0V 038:02:00 (07 Feb) Portier 3 RAP
Survey ---- 042:17:10 (11 Feb) ------ - ENG
HD 88746 G8V 043:00:30 (12 Feb) Portier 3 RAP
EUVE J0512-006 WD:DA 043:13:00 (12 Feb) Dupuis 2 EGO
HD 98281 G8V 043:13:00 (12 Feb) Portier 3 RAP
WD 0549+158 WD:DAw 050:12:20 (19 Feb) Lallement 1 EGO
T Leo DwfNva 052:02:10 (21 Feb) Mumma 1 EGO,TOO,TCO,COO
GL 205 M1.5V 054:07:45 (23 Feb) Giampapa 1 EGO
beta CMa B1... 055:02:45 (24 Feb) Cassinelli 2 EGO,COO,CFG
T Leo DwfNva 055:23:15 (24 Feb) Mumma 1 EGO,TOO,TCO,COO
beta CMa B1... 058:01:45 (27 Feb) Cassinelli 2 EGO,COO,CFG
=======================================================================
Key to Notes:
CFG = Observation required non-standard payload configuration
COO = Coordinated observation
EGO = EUVE Guest Observer observation
ENG = Engineering period to calibrate star trackers and
gyroscopes
RAP = Right-Angle Program observation
TCO = Time-critical observation
TOO = Target of Opportunity
1. EUVE Science News
====================
1.1 Public GO/RAP Data Release for 1 Apr 1997
---------------------------------------------
by Dr. Nahide Craig, EUVE User Support Scientist
The table below lists the GO/RAP observations that become public on
1 Apr 1997. For each observation is given the target name, the
approximate exposure time in ksec, the GMT start/end dates, the
target's spectral type, and the data identification code (GO and RAP
data are marked accordingly). 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 via postal mail on 8mm tape
or (if requested) on CD-ROM.
The data rights policies for observations state that Principal
Investigators (PIs) have proprietary rights to the data for a given
period of time 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 proprietary period begins after the PI is sent the final
piece of the completed observation. See the UCB-CEA WWW site (address
below) for a complete list of publicly available EUVE data products.
===============================================================
Target ~Exp Observation Dates SpT DataID
Name (ksec) Start End
===============================================================
GO DATA SETS AVAILABLE 1 APR 1997:
Cycle 4 Targets
Jupiter 85 28 Aug - 31 Aug 1996 SolSys go0530
QS Tel 28 31 Aug - 01 Sep 1996 CV:AM go0531
V711 Tau 136 01 Sep - 06 Sep 1996 G9V go0532
V711 Tau 136 06 Sep - 11 Sep 1996 G9V go0533
HU Aqr 88 11 Sep - 14 Sep 1996 CV:AM go0534
Cycle 3 Targets
EI Eri 21 25 Nov - 26 Nov 1995 G5IV go0535
V837 Tau 70 06 Dec - 08 Dec 1995 G2V go0536
EK Dra 100 06 Dec - 10 Dec 1995 F8 go0537
RE 1149+28 1 13 Dec - 13 Dec 1995 CV:AM go0538
2EUVE J0723-27.7 7 07 Feb - 07 Feb 1996 NOID go0539
2EUVE J0723-27.7 91 09 Feb - 12 Feb 1996 NOID go0540
RAP DATA SETS AVAILABLE 1 APR 1997:
NGC 6853 288 11 Aug - 21 Aug 1996 PlanNeb rap0079
0117-286 85 28 Aug - 31 Aug 1996 AGN rap0080
0119-286 85 28 Aug - 31 Aug 1996 AGN rap0081
0006+18 28 31 Aug - 01 Sep 1996 NeutSt rap0082
================================================================
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 UCB-CEA
personnel, the UCB-CEA publication numbers are indicated. Unless
otherwise noted, researchers may obtain preprints of the UCB-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 and for
posting under the UCB-CEA/EUVE WWW site. Please send all abstracts to
archive@cea.berkeley.edu.
--------------------------------------------------------------
SIMULTANEOUS EUV AND OPTICAL OBSERVATIONS OF THE MAGNETIC CATACLYSMIC
VARIABLE PQ GEMINORUM
S.B. Howell, M.M. Sirk, G. Ramsay, M. Cropper, S.B. Potter, and S.R.
Rosen
To appear in Astrophysical Journal.
We present the results of simultaneous optical polarimetry and EUV
spectroscopy and photometry of PQ Gem, a magnetic cataclysmic variable
which shows observational properties of the strongly magnetic AM Her
class, as well as the weaker field DQ Her stars. The EUV spectrum of
PQ Gem is weak, showing continuum blueward of 80 A and a few possible
weak emission lines due to Mg, Si, and Ne. The EUV lightcurve has a
similar appearance to previous X-ray data obtained for PQ Gem,
including a narrow "dip" feature which is modulated with the white
dwarf spin period. Observed polarisation variations on the spin
period, modeled by a slightly modified version of that used in Potter
et al. (1997), matched the optical light curve and linear polarisation
curve reasonably well, but not the position angle variation. The EUV
properties of PQ Gem can also be understood in the context of this
model.
--------------------------------------------------------------
SPECTROSCOPY AND PHOTOMETRY OF EUVE J1429-38.0: AN ECLIPSING MAGNETIC
CATACLYSMIC VARIABLE
S.B. Howell, N. Craig, B. Roberts, and M. Sirk
To appear in Astronomical Journal. [UCB-CEA publication #779]
The source EUVE J1429-38.0 was originally discovered by the Extreme
Ultraviolet Explorer (EUVE) satellite. Initial extreme ultraviolet
(EUV) photometry showed periodic variations every 2 h 22 m, which
Craig et al. (1996) determined to be the orbital period. We present
new optical observations that confirm the above stated period, but
which unambiguously show this star to be an eclipsing system with a
true orbital period of 4 h 46 m, twice the previously reported period.
The photometric data are strongly modulated by ellipsoidal variations
during low states, and our time-resolved optical spectra, which cover
only about one-third of the orbital cycle, indicate the clear presence
of a gas stream. During high states, the CV shows ~1 mag deep
eclipses and the apparent formation of a partial accretion disk. EUVE
J1429-38.0 presents the observer with properties of both the AM
Herculis and the DQ Herculis types of magnetic cataclysmic variable.
--------------------------------------------------------------
KINEMATICAL STRUCTURE OF THE LOCAL INTERSTELLAR MEDIUM: THE GALACTIC
CENTER HEMISPHERE
R. Genova, J.E. Beckman, S. Bowyer, and T. Spicer
To appear in Astrophysical Journal. [UCB-CEA publication #780]
A survey of interstellar Na I D1 and D2 absorption features found
in the spectra of 31 early type stars in the first and fourth Galactic
quadrants reveals a new picture of the large-scale kinematics of
interstellar gas in the vicinity of the Sun. While absorption
features found in the spectra of stars in the fourth Galactic quadrant
show the gas expanding from stars in the Scorpio-Centaurus OB
association, stars in the first Galactic quadrant, in the range of
distances covered by this survey (74-312 pc from the Sun), show
interstellar gas falling toward the Galactic plane with a bulk motion
whose component parallel to that plane is directed *toward* the
Scorpio-Centaurus association. This picture differs completely from
generally accepted models in which the nearby interstellar gas flows
away from the Scorpio-Centaurus association toward the Galactic
anti-center. Evidence for the presence of an expanding shell-like
feature that is reaching the Solar System is presented.
--------------------------------------------------------------
THE ACCRETING WHITE DWARF IN THE CLOSE BINARY EUVE J1016-053
S. Vennes, J. Dupuis, S. Bowyer, and A.K. Pradhan
To appear in Astrophysical Journal Letters. [UCB-CEA publication #782]
The hot white dwarf in the close binary EUVE J1016-053 (=RE
1016-053) has been classified a DAO white dwarf; its mixed H/He
composition has been attributed to steady accretion from the close red
dwarf companion. We have obtained extreme ultraviolet (EUV)
photometric and spectroscopic observations of EUVE J1016-053 with the
Extreme Ultraviolet Explorer (EUVE). We report the discovery of a
~30% EUV flux variation over a period of 57.3 m which we attribute to
surface abundance inhomogeneities modulated over the stellar rotation
period, P_rot. The EUVE spectrum shows the effect of heavy element
opacities on the white dwarf EUV energy distribution. Spectral
synthesis including trace opacities of helium and a group of heavy
elements (C, N, O, Si, S, Fe) in the otherwise hydrogen-rich
atmosphere constrains abundances to Y/Y_sun = Z/Z_sun = 2E-03, in
support of a simple accretion model. The low surface-averaged helium
abundance measured in the white dwarf atmosphere limits the accretion
rate to 1E-19 - 1E-18 M_sun/yr, i.e., much lower than the Bondi-Hoyle
accretion rate, which is of the same order as the red dwarf mass loss
rate (>= 1E-14 M_sun/yr), therefore invalidating a simple
wind-accretion model. We speculate that weak mass loss from the white
dwarf or interaction with a magnetosphere may inhibit accretion onto
the white dwarf. Accretion of heavy elements may also be restricted to
smaller areas possibly correlating to magnetic poles.
--------------------------------------------------------------
EUVE OPTICAL IDENTIFICATION CAMPAIGN III. A SOUTHERN HEMISPHERE SAMPLE
OF ACTIVE LATE TYPE STARS AND WHITE DWARFS
N. Craig, D. Christian, J. Dupuis, and B. Roberts
To appear in Astronomical Journal. [UCB-CEA publication #784]
We present optical identifications of 30 previously unidentified
extreme ultraviolet (EUV) and soft x-ray sources coinciding with the
position of faint sources detected during the all-sky surveys of the
Extreme Ultraviolet Explorer (EUVE) in the 58-174 A (0.071-0.214 keV)
band and of the ROSAT Position Sensitive Proportional Counter (PSPC)
in the 5-120 A (0.1-2.4 keV x-ray) band. We present low-resolution
spectra of the possible optical counterparts of the x-ray and EUVE
sources obtained with the 1.5 m telescope at CTIO in 1995 May and
December and 1996 February. The optical counterparts for 23 sources
are identified as late-type (dKe and dMe) stars, and 4 are identified
as new DA white dwarfs. All spectra of sources identified as
late-type stars show the Balmer series and Ca H and K lines in
emission, indicating the signature of chromospheric activity. For the
white dwarfs, the joint detection by the ROSAT PSPC and the EUVE Lexan
band indicates that they have a low-abundance of metals and that their
EUV emission is mostly attenuated by the local interstellar medium
(ISM).
--------------------------------------------------------------
2. EUVE Satellite Operations News
=================================
2.1 UCB-CEA Begins Realtime Operations of EP Spacecraft
-------------------------------------------------------
On 3 Feb UCB-CEA began Phase 2 of shadow operations for the
Explorer Platform (EP) spacecraft. In this phase UCB-CEA assumed all
responsibilities for realtime spacecraft command and control
operations, with the GSFC Flight Operations Team (FOT) shadowing for
safety purposes. UCB-CEA began Phase 1 of shadow operations when it
assumed all spacecraft scheduling responsibilities on 3 Jan. At a
review of UCB-CEA's spacecraft operations performance on 25 Feb, a
date of 14 Mar was established for the official handover of operations
responsibility from GSFC to UCB-CEA. This handover will effectively
complete the outsourcing of EUVE EP spacecraft operations, a project
that has been in the works for over a year.
2.2 EUVE Target of Opportunity: T Leo
-------------------------------------
Late on 21 Feb a Target of Opportunity (TOO) was called to the
source T Leo. It took UCB-CEA about four hours to complete the
planning and execution of the TOO, from the time of notification to
the final uplink of new products to the spacecraft (this response time
was a 50% improvement over UCB-CEA's first TOO attempt to an ALEXIS
transient on 28 Jan). The slew to T Leo was completed about an hour
after product uplink, early on 22 Feb. Because the Moon entered the
field of view of the deep survey/spectrometer instrument on 23-24 Feb,
the TOO observation was split into two pieces, with EUVE observing the
original science target, beta CMa, in the interim. The TOO was
conducted smoothly and no problems were encountered.
2.3 Extended Survey Period for Spacecraft Calibrations
------------------------------------------------------
A ~20-hour calibration observation was conducted on 11-12 Feb. The
first ~7 hours consisted of a survey period to calibrate the star
trackers; the remaining ~13 hours were spent performing a multi-slew
calibration of the on-board gyroscopes. Implementation of the
calibration observation proved to be an excellent test of the training
and experience of the UCB-CEA FOT; everything went smoothly, with all
planning, product generation, and command uplink begin conducted by
and at UCB-CEA. The resulting data has been passed to GSFC's Flight
Dynamics Facility (FDF) for analysis.
2.4 UCB-CEA Handles Its First Spacecraft Anomaly
------------------------------------------------
On 27 Feb the UCB-CEA FOT experienced, and was tested by, its first
major spacecraft operations anomaly situation. At the beginning of
03:05z - 03:25z realtime contact there was no radio frequency (RF)
communication link established with the spacecraft (i.e., a "negative
acquisition"). The last half of this contact showed intermittent RF,
but subsequent events showed none.
The FOT's subsystems engineers were called in to investigate and
resolve the anomaly. Within a few hours they determined that the
high-gain antenna (HGA) gimbal table on-board the spacecraft was
incorrect; this table informs the spacecraft of the times of realtime
contacts in order to allow the gimbals to steer the HGA so that it can
acquire the relevant Tracking Data and Relay Satellite (TDRS) at the
appropriate time, which then routes the telemetry/command data to/from
the operations center on the ground. As a result of the incorrect
gimbal table, the HGA tried to track TDRS, which was out of its
relatively narrow field of view (FOV); the HGA then ran up against its
stops and its software disabled itself.
The subsequent lack of telemetry and contact with the spacecraft,
coupled with concerns about excessive heating of the HGA gimbals (a
problem seen in the past), prompted the FOT to switch communications
from the HGA to the low-gain (but wide FOV) omni antennae. Telemetry
was then acquired showing that the spacecraft was healthy and that all
temperatures were within their operating limits.
GSFC's FDF then generated a new gimbal table that was uplinked to
the spacecraft. With a few pointers from members of the shadowing
Lockheed FOT, the spacecraft was then reconfigured back to its nominal
state. Communications were then switched back to the HGA and normal
operations resumed.
Overall, this anomaly was a great test of the readiness and
response of the UCB-CEA FOT, an experience that provided them with a
number of important and valuable lessons.
2.5 On-Line Access to EUVE
--------------------------
Listed below are the various methods for on-line access to EUVE:
o UCB-CEA World Wide Web (WWW) at URL: http://www.cea.berkeley.edu/
o anonymous FTP: ftp.cea.berkeley.edu
o EUVE Electronic Newsletters
Past issues -- available via the UCB-CEA WWW site
Subscriptions -- mail majordomo@cea.berkeley.edu ("subscribe
euvenews")
Post message (moderated) 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 UCB-CEA can help YOU! For more information see the UCB-CEA
WWW site or contact the Archive (archive@cea.berkeley.edu).
o Public RAP
The Public Right Angle Program (RAP) is a simple and 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 UCB-CEA WWW site (address below) 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 EGO Center:
Center for EUV Astrophysics
2150 Kittredge St.
Berkeley, CA 94720-5030
510-642-3032 (voice)
510-643-5660 (fax)
archive@cea.berkeley.edu
egoinfo@cea.berkeley.edu
3. EUVE Outsourced Extended Mission Status Report
=================================================
by Brett Stroozas, EUVE Flight Operations Manager
Work continues to outsource EUVE Explorer Platform (EP) spacecraft
operations from GSFC to the EUVE Platform Operations Center (EPOC) at
UCB-CEA. Upon completion of the operations handover, which is
scheduled for mid-Mar 1997, the EUVE Outsourced Extended Mission (OEM)
will commence. The following sections describe some of the
outsourcing highlights from Feb 1997.
3.1 Commencement of Phase 2 "Realtime" Shadow Operations
--------------------------------------------------------
At a telecon on 31 Jan between GSFC and UCB-CEA it was agreed that
UCB-CEA was ready to begin Phase 2 of the shadow operations period:
realtime operations. In Phase 2 UCB-CEA would augment its scheduling
responsibilities from Phase 1 (which began on 3 Jan) by assuming the
remaining realtime responsibilities for command and control of the EP
spacecraft.
At the telecon the participants reviewed UCB-CEA's performance
during the Phase 1 scheduling shadow operations period, which had
proceeded very smoothly. They then reviewed and discussed the UCB-CEA
performance criteria required for the beginning of Phase 2, and the
remaining open operational issues. Although much work remained to be
done, everyone agreed that Phase 2 of shadow operations should begin
as scheduled on 3 Feb. As of that date UCB-CEA assumed all direct
operational control of the EP spacecraft.
On 12 Feb Mr. Kevin Hartnett, the EUVE Mission Director at GSFC,
visited UCB-CEA, reviewing the operations center and watching its FOT
in action. Mr. Hartnett then spent the remainder of the day working
remaining outsourcing issues with his counterpart at UCB-CEA, Mr.
Brett Stroozas.
On 25 Feb a follow-up shadow operations status review telecon was
held between UCB-CEA and GSFC. Once again, UCB-CEA's performance
during the shadow operations period was evaluated and all parties
agreed that everything was proceeding well and on schedule! The date
of 14 Mar was set for the official handover of spacecraft operations
from GSFC to UCB-CEA.
3.2 Remote Support Site at GSFC SDVF
------------------------------------
The Software Development and Validation Facility (SDVF) at GSFC has
been chosen as the site for remote (from GSFC) anomaly support for
EUVE. This site will be used by remote experts at GSFC who are called
in by UCB-CEA to support non-routine and/or anomaly spacecraft
situations. Communications lines to the SDVF were installed,
configured, and tested in order to verify proper receipt and
decommutation of normal (32 kbps) and contingency (1 kbps) realtime
data from the spacecraft. Technical issues are currently being worked
to provide additional capabilities (e.g., remote TPOCC display) that
will give remote experts more insight into the data stream.
3.3 EPOC Ground Systems Status
------------------------------
A number of issues continue to be worked in regards to the EPOC
ground system components, the bulk of the issues being related to the
Transportable Payload Operations Control Center (TPOCC) -- the command
and control system for the EP spacecraft. GSFC delivered to CEA a few
new software patches that resolved numerous bugs; some new bugs have
also been identified via on-going realtime operations. The UCB-CEA
FOT has informed the TPOCC development team at GSFC of these issues,
and the team currently working to resolve those that are deemed most
critical.
After some initial setup and configuration problems the second
TPOCC "string" and the accompanying TPOCC switch are now fully
operational and are being used continuously at UCB-CEA. A number of
successful switches between the two strings has demonstrated the
ability of the systems to easily move from primary to backup string
and vice versa. Software developers at UCB-CEA have also completed
code that allows TPOCC to process the final EUVE archival data
resident at UCB-CEA; this means that all new and archival EUVE flight
data can now be processed through the TPOCC systems at UCB-CEA.
3.4 Performance Criteria Update
-------------------------------
A number of very important performance criteria were demonstrated
by UCB-CEA during the month. The UCB-CEA FOT successfully implemented
hardware and software loads, as well as software patches, on the EP
simulator at GSFC. The simulator was also used to demonstrate
UCB-CEA's ability to recover from safe-point mode. Other major
accomplishments included the successful planning and execution of the
extended survey period to calibrate the star trackers and gyroscopes.
Finally, the Lockheed-Martin FOT at GSFC completed the conversion and
testing of all TPOCC spacecraft operations procedures, and delivered
them to UCB-CEA.
--------------------------------------------------------------------------
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. Roger F.
Malina and Professor Stuart Bowyer. EUVE Flight Operations Manager
and Newsletter Editor: Brett A. Stroozas. Funded by NASA/UCB
Cooperative Agreement NCC5-138. Send newsletter correspondence to
ceanews@cea.berkeley.edu.
The EUVE project is managed by NASA's GSFC: Bill Worrall, GSFC
Project Manager; Dr. Yoji Kondo, Project Scientist; Dr. Ronald
Oliversen, Deputy Project Scientist; Mr. Kevin Hartnett, Mission
Director. NASA HQ: Dr. Guenter Riegler, Program Manager.
Information on the EUVE GO Program is available from Dr. Ron
Oliversen, Mail Code 681, GSFC, Greenbelt, MD 20771 at (301)
286-6290 or e-mail to euve@stars.span.nasa.gov.
END-----------EUVE------------ELECTRONIC---------------NEWS-------------END
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