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ELECTRONIC NEWSLETTER OF THE EUVE OBSERVATORY
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Vol 3, No. 16 December 6, 1993 ISSN 1065-3597
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Notes from the Editor
=====================
by Brett A. Stroozas, DASS/Archive Manager
Welcome to this addition of the electronic newsletter for the Extreme Ultra-
violet Explorer satellite (EUVE). The mission is now in the 11th month of the
Guest Observer (GO) phase in which EUVE makes long-exposure spectroscopic ob-
servations of specific NASA-approved GO targets. The satellite continues to
perform extremely well. This issue of the EUVE electronic newsletter, which
is compiled and published at the Center for EUV Astrophysics (CEA) in Berkeley,
CA, contains the following:
1. an introduction to the EUVE User's Committee
2. abstracts of recently accepted EUVE-related science papers
3. news from the EUVE Guest Observer (EGO) group
4. news from the CEA Educational Outreach program
5. news regarding the EUVE CD-ROM series
6. listing of available jobs at CEA
Please send any comments and/or suggestions related to this newsletter to
ceanews@cea.berkeley.edu (Internet).
1. EUVE User's Committee Members
================================
The EUVE User's Committee (formerly known as the EGOWG -- EUVE Guest Ob-
server Working Group) was established as an advisory committee to the Project
Scientist at Goddard Space Flight Center regarding all aspects of the EUVE
GuestObserver Program. The group meets periodically to review the EGO Center
progress (e.g. in software development) and to comment on future plans. As
announced in last month's newsletter, the next EUVE User's Committee meeting
will be held at the American Astronomical Society (AAS) Conference on Thursday,
13 January 1994, for everyone interested in extreme ultraviolet astronomy
(members of the user community are encouraged to attend). The current members
of the Users' Committee are as follows:
Name Affiliation E-mail Address
---- ----------- --------------
Shipman, Harry (Chair) U. of Delaware eod00391@udelvm.udel.edu
Bagenal, Fran U. of Colorado bagenal@pele.colorado.edu
Bruhweiler, Fred Catholic U. of America bruhweiler@iue.dnet.nasa.gov
Cassinelli, Joe U. of Wisconsin cassinelli@macc.wisc.edu
Dupree, Andrea SAO dupree@cfa.harvard.edu
Holberg, Jay U. of Arizona holberg@looney.dnet.nasa.gov
Howell, Steve Plan. Science Inst. howell@5470.dnet.nasa.gov
Judge, Phil NCAR judge@hao.ucar.edu
Nousek, John Penn St. U. nousek@astro.psu.edu
For more information regarding the members and/or activities of the User's
Committee, please contact the EGO group at egoinfo@cea.berkeley.edu (Internet).
2. Abstracts of Recently *Accepted* EUVE Papers
===============================================
Included below are abstracts of EUVE-related papers recently *accepted* for
publication in refereed journals. GOs are invited to contribute accepted ab-
stracts for inclusion in future editions of this newsletter. Abstracts should
be sent to egoinfo@cea.berkeley.edu.
--------------------------------------------------------------
LOW DENSITY OF NEUTRAL HYDROGEN AND HELIUM IN THE LOCAL ISM: EUVE PHOTOMETRY
OF THE LYMAN CONTINUUM OF THE HOT WHITE DWARFS MCT 0501-289, MCT 0455-281,
HZ 43, and GD 153
S. Vennes, J. Dupuis, S. Bowyer, G. Fontaine, A. Wiercigroch, P. Jelinsky,
F. Wesemael, and R.F. Malina
to appear in Astrophysical Journal Letters
The first comprehensive sky survey of the extreme ultraviolet (EUV) spectral
range performed by the Extreme Ultraviolet Explorer (EUVE) has uncovered a
handful of very bright sources at wavelengths longer than the HeI 504 A photo-
ionization edge. Among these objects are four white dwarfs with exceptionally
low interstellar medium (ISM) column densities along the line of sight. Anal-
ysis of EUV photometry of the He-rich DO white dwarf MCT 0501-2858 and the
H-rich DA white dwarf MCT 0455-2812 along one line of sight and of the DA
white dwarfs HZ 43 and GD 153 near the north Galactic pole indicates that the
overall minimum column density of the neutral material centered on the Sun is
N_(HI) = 0.5-1.0e18 cm^(-2). In the case of MCT 0501-2858, EUV photometric
measurements provide a clear constraint to the effective temperature (60000-
70000 K). Given these neutral hydrogen columns, the actual contribution to
the density of neutral species from the immediate solar environment (the "local
fluff") would only cover a distance of ~2-3 pc (assuming an average density
n__(HI) = 0.1 cm^(-3)) leaving these lines of sight almost entirely within the
hot phase of the ISM. A preliminary examination of the complete EUVE long
wavelength survey indicates that these lines of sight are exceptional and set
a minimum column density in the solar environment.
Subject Headings: ISM: abundances -- ISM: structure -- ultraviolet: stars
-- white dwarfs
--------------------------------------------------------------
DETECTION OF ROTATIONAL MODULATION IN THE CORONAL EUV EMISSION FROM V711 TAURI
J.J. Drake, A. Brown, R.J. Patterer, P. Vedder, S. Bowyer, and E.F. Guinan
to appear in Ap. J. Lett.
The RS CVn binary V711 Tauri was observed by the Extreme Ultraviolet
Explorer satellite (EUVE) twice during the latter half of 1992, for periods
lasting several days. Light curves for the waveband 60-180 A derived from
the all-sky survey scanning in August, and from a pointed calibration
observation made in October, both exhibit a modulation of about 40%. The
modulation in both data sets is very similar, with minimum flux occurring
near orbital phase phi=0.5. Analysis using a two temperature optically thin
plasma emission model reveals that most of the detected extreme ultraviolet
(EUV) flux emanates from hot (~1e7 K) coronal plasma. The modulation is pro-
bably mostly due to either flare-like activity or to rotational occultation
of a long-lived, compact and especially bright coronal structure on the more
active star of the system. The phased data support the latter hypothesis.
This coronal structure is then likely to be associated with the persistent
spot patterns seen on V711 Tau when using Doppler and photometric surface
imaging techniques. Comparison with contemporaneous Stromgren b-band photo-
metry indicates that the optical minimum light leads the EUV maximum light
by 90 degrees in phase.
Subject Headings: stars: activity -- coronae -- late-type -- binaries: close
-- X-rays: stars
--------------------------------------------------------------
List of CEA EUVE-Related Abstracts for January AAS Meeting:
-----------------------------------------------------------
1. Implications of Initial Results from the EUVE Observatory for the FUSE EUV
Spectrometer and a Possible EUVE Extended Mission
R.F. Malina, D. Finley, J. Warren, A. Fruscione, J. Edelstein, and B. Haisch
2. Hands-on Demonstration of the Extreme Ultraviolet Explorer Satellite Orbit
I. Hawkins and R.F. Malina
3. Expansion of the EUVE Science Archive: New Products and Services
E. Polomski, B. Stroozas, J. Drake, K. Chen, and T. Chen
4. A Low Cost Approach to EUVE Spacecraft Operations: The Future in Astro-
physical Satellite Operations?
D. Biroscak, P. Ringrose, M. Samuel, G. Wong, L. Wong, J. Din, F. Kronberg,
and D. Meriwether
5. Preliminary Results of the EUVE Right Angle Program
K.E. McDonald, N. Craig, M.M. Sirk, J.J. Drake, and R. F. Malina
6. Possible Detection of a Nearby Supernova Remnant at High Galactic Latitudes
R. Lieu, C. Hwang and S. Bowyer
7. Extreme Ultraviolet Observations of AGNs and BL Lac Objects
T.E. Carone and A. Fruscione
8. EUVE Observations of Planetary Nebulae
A. Fruscione, M. Abbott, J.J. Drake, J. Dupuis, R.F. Malina, M. Mathiou-
dakis, K. McDonald, and K.C. Chu
9. EUV emission from the low activity dwarf HD 4628
M. Mathioudakis, J.J. Drake, J.H.M.M. Schmitt, K. McDonald, and S. Bowyer
10. Coronal Variability in the Extreme Ultraviolet
J.J. Drake, M. Mathioudakis, J.P. Pye, A. Fruscione, S. Bowyer,
P.W. Vedder, and R.J. Patterer
11. EUVE Spectroscopic Observation of the 1992 July 15 Flare on AU Mic
M. Abbott, S. Cully and G. Fisher
12. The First EUVE Source Catalog
J. Lewis, S. Bowyer, R. Lieu, M. Lampton, X. Wu, J.J. Drake,
and R.F. Malina
13. Spectroscopic and Orbital Properties of the Binary Feige 24 and Discovery
of External Plasma at Inferior Conjunction
S.Vennes and J.R.Thorstensen
14. Discovery of Strong EUV-induced Balmer Emission in the New WD+dM Binary
EUVE J2013+40.0 (RE 2013+400)
J.R. Thorstensen and S. Vennes
15. The Luminosity Function of Hot DA White Dwarfs from an EUV-Selected Sample
J. Dupuis, S. Vennes and S. Bowyer
3. Notes from the EUVE Guest Observer (EGO) Program
===================================================
3.1 Spectrometer Dithering Test Results
by Anne Miller, EGO Technical Writer
The problem of fixed pattern detector noise in the spectrometer can intro-
duce spurious features in observations of bright sources. To alleviate this
effect in the absence of usable flat field images, the EGO Center has conducted
experiments in which the spectrometer pointing was "dithered," by moving the
spectrometer each orbit to one of 30 randomly chosen pointings within a radius
of 1 arc minute. This effectively "washes out" the fixed patterns caused by
deformed micro-channels. The pointing errors were corrected by the standard
EGO Center data processing to refocus the spectra.
The results from a dithered observation of the white dwarf G191-B2B were
compared to a previous observation of the same star, and the signal to noise
for the medium wavelength spectrum was increased by more than a factor of two.
The agreement between flux measurements performed in the overlapping regions of
the medium- and long-wavelength channels was also greatly improved. The EGO
Center will recommend dithering for other sources based on source brightness
and other criteria.
3.2 Earth Blockage
by Anne Miller, EGO Technical Writer
The pointing range of the Deep Survey/Spectrometer (DS/S) was increased
after tests last August to include angles of up to 90 degrees from anti-sun.
The increased pointing range means it is also more likely that the earth will
impinge on the spectrometer's line-of-sight during parts of some pointed ob-
servations. The EGO Center recommends that GO's whose observations were made
after the mini-IOC in August check their data for signs of earth blockage.
If earth blockage has occurred during orbit nighttime, this will change the
effective exposure time, and any flux measurements made with the uncorrected
exposure will be on the low side.
Earth blockage is defined by a simple geometrical condition, and there are
two ways to search the data for its occurrence. Blockage can be defined in
terms of the angle between the satellite zenith and the DS/S pointing vector,
the quantity called "DSSZEN" which can be calculated from the telemetry tables
by the IRAF/EUV task BACKMON.
It is assumed that looking through the Earth's atmosphere 200 Km above the
Earth's surface will produce an unacceptable attenuation of EUV source flux.
The conditions under which blockage occurs depend on the atmospheric altitude
(A) up to which the line-of-sight is considered blocked, the Earth's radius
(Re), and the mean height (H, ~516 Km) of the satellite above the Earth.
Re + A
DSSZEN > 180 - B, where: sin(B) = --------
Re + H
For values of A from 200 to 450 Km, the value of 180-B ranges from 107.41 to
97.93 degrees. The value of H is an average of mean orbit apogee and perigee
for a typical observing week. GO's should bracket this value in their calcu-
lations, as well as making a determination of the maximum value of A that is
acceptable.
GO's should first run BACKMON using their telemetry tables to produce the
DSSZEN angle, and search for periods when this angle exceeds their chosen li-
mit. This can be easily done using the task DQSELECT to display DSSZEN from
the table produced by BACKMON, setting an upper limit, and creating a table
of good times in conjunction with the standard limits on detector ADC counts.
A second test for Earth blockage would be to create a light curve from the
HeII 304 A airglow feature in the medium wavelength channel. The airglow
should show a marked decrease if the Earth limb enters the line-of-sight, and
should drop to nearly zero for periods when blocked by the earth disk. The
behavior of the airglow light curve may help users fine tune the duration of
the Earth blockage more easily than the numerical calculations above.
3.3 Error in GO Flux Values from the DS/S Scanner
by Kelley McDonald, Data Analysis Support Staff
and Jean Dupuis, EGO Center Scientist
The flux values computed from the Deep Survey data for all Guest Observer
targets processed before 3 Dec 1993 are incorrect. The grasp values that were
used to convert count rate to flux were out-of-date and incorrect. All Guest
Observers that have received these data can compute the correct flux values by
multiplying the received fluxes by 0.5748 -- the ratio of the old grasp value
to the new one. Errors in the fluxes will also need to be multiplied by this
factor. The units of the fluxes and errors are ph/cm^2/s/A.
3.4 EUVE on the World Wide WEB
by Anne Miller, EGO Technical Writer
The EUVE Guest Observer Center at CEA now has a home page in the NCSA MOSAIC
Web browser. The World Wide Web is a network-spanning communications program
that transmits hypertext documents and images in standard formats.
X windows users running MOSAIC can visit the CEA home page, access the CEA
anonymous ftp site, "gopher" server, and an operations page that supplies
weekly reports on EUVE and proposal database information. GO proposals in the
database can be accessed by proposal number, target name, observation date, or
Principal Investigator (PI) name. Experimental (use at your own risk!) services
include a target visibility test for EUVE pointed observations and facilities
to register for various EGO Program electronic mailing lists.
The CEA home page Uniform Resource Locator (URL) is:
http://ftp.cea.berkeley.edu/
and can be entered from the NCSA "What's New" page under "What's New for Octo-
ber" (about a third of the way down the page).
4. CEA Educational Outreach Efforts
===================================
by Nahide Craig, Data Analysis Support Staff
[Editor's note: In order to provide educational opportunities, particularly in
view of NASA's interest in promoting educational outreach with K-12 audiences,
CEA has established an educational outreach program. Included below are news
notes on two areas of this effort.]
4.1 FAX Friends
The first EUVE Education Outreach Advisory Board met at CEA on 23 November
1993. In addition to encouraging CEA staff to participate in educational out-
reach efforts, a major outcome of the meeting was the establishment of a part-
nership for educational opportunities between CEA and one member of the Board,
the associate superintendent of the Lodi Unified School District (LISD), who
immediately directed CEA to some of the LISD special programs (e.g., a special
technical high school for the underachieving, an underserved gifted minority
students program and a gifted program in one of the elementary schools).
To be immediately implemented is the "FAX Friends" concept. The idea
here is for CEA members to give a presentation on EUVE in a chosen LISD school
in order to spark interest in Space Science and Astronomy and to start a dialog
with students and teachers. A FAX machine will then be used to conduct ques-
tion-and-answer correspondence between the school and the CEA community.
4.2 Project ASTRO Parters
Drs. Isabel Hawkins and Nahide Craig have established a partnership with
two 5th grade teachers at the Sequoia Elementary School in Oakland, CA. This
partnership is part of the Astronomical Society of the Pacific's Project ASTRO,
a state-wide project that links amateur and professional astronomers with
teachers and students in grades 4-9. The relevant partners attended a 2-day
Project ASTRO training workshop in October at Stanford University and are
currently working together to plan activities and projects in, and out, of
the classroom.
Two classroom meetings in the Oakland elementary school have already been
held. The purpose of the first meeting, which was devoted to Astronomy as a
career, was to raise interest in Astronomy and serve as an ice-breaker between
students/teachers and the astronomers. A slide show of Craig and Hawkins as
working astronomers, and another on celestial objects was followed by lively
question and answer sessions.
In the second meeting, the phases of the Moon were demonstrated. The stu-
dents, using the results of previous homework assignments in which they made
and recorded observations of the Moon, proposed their ideas on the causes of
the phase phenomena. Each student then participated in a visual demonstration
-- using a 200 watt light bulb as th Sun, their head as the Earth and a sty-
rofoam ball as the Moon -- which displayed the Moon's phases as it orbits the
Earth. Another discussion was then held to discuss what was observered and
learned.
The next visit will include a Tour of the Solar System to compare and study
the Planets.
5. EUVE Science Archive Notes: Second Installment in the EUVE CD-ROM Series
============================================================================
by Brett A. Stroozas, DASS/Archive Manager
As the EUVE mission moves into 1994, the proprietary data rights associated
with EUVE data will begin to expire. GO observations begin to go public in
April, 1994, and the all-sky survey data will follow in August. In preparation
for these milestones, and in order to make this data easily accessible to the
astronomical community, the EUVE Science Archive group is bustling with acti-
vity. Operationally, the Archive has been established to distribute and make
accessible EUVE-related data and services via a variety of methods including
the CEA anonymous ftp site, the CEA node of NASA's Astrophysics Data System
(ADS) and the EUVE CD-ROM series (the implementation of network tools such as
Mosaic, gopher and WAIS is also underway). This article focuses on the next
upcoming installment in the CD-ROM series.
As many of you know, Volume 1, Number 1 of the EUVE CD-ROM series was re-
leased at the June, 1993, AAS in Berkeley, CA. This disc contained various
EUVE-related data, software and documentation, highlighted by a GO observation
of the late-type star AT Mic.
The Archive group is presently in the final production stages for Volume 2,
Number 1 (A,B and C) of the CD-ROM series which is to distributed at the Janu-
ary, 1994, AAS meeting in Washington, D.C. For this set of three CDs, NASA has
approved the early release of 11 GO calibration observations from the in-orbit
calibration and all-sky survey phases of the mission. These observations have
been arranged thematically on the three discs as follows:
o disc A contains the four White Dwarfs WD1845+019 (observed on 06/28/92,
exposure of approximately 27 ksec), Feige 24 (11/20/92, 58 ksec),
G191-B2B (12/15/92, 45 ksec), and WD0549+158 (01/10/93, 60 ksec)
o disc B contains the two Late-type stars Capella (12/12/92, 75 ksec) and
Procyon (01/15/93, 97 ksec)
o disc C contains five assorted targets including the White Dwarf WD1620-391
(06/25/92, 32 ksec), the Cataclysmic Variable RE1938-461 (07/09/92,
40 ksec), the BL Lac object PKS2155-304 (07/21/92, 34 ksec), the Late-
type star HR1099 (10/24/92, 75 ksec), and the Moon (12/10/92, 1.5 ksec)
In addition to the relevant GO data sets, each disc will also contain:
o software -- the latest versions of the EGO Center software and reference data
used to process the included observations
o all-sky survey data -- the full text, figures and tables for the two survey
papers:
(1) The Extreme Ultraviolet Explorer Bright Source List
Malina, R.F., et al.
Astronomical Journal, February 1994 (in press)
(2) The First EUVE Source Catalog
Bowyer, C.S., et al.
Astrophysical Journal Supplement (submitted)
(These papers are also available in the CEA ftp site.)
o assorted documentation -- includes past issues of this newsletter, abstracts
of CEA EUVE papers, some overview articles regarding specific aspects
of the mission (as taken from the special EUVE edition of the Journal
of the British Interplanetary Society, 46(9), September, 1993), and
other miscellaneous mission-related documents
Planning for the long-term CD distribution will begin shortly. The Archive
group would appreciate any comments and/or suggestions from you, the user com-
munity, regarding ways in which EUVE data could best be presented on CD to make
them most useful scientifically.
To obtain more information regarding the EUVE Science Archive, please send
e-mail to archive@cea.berkeley.edu (Internet) and include the word "help"
(quotes omitted) as the body of the message. A mailserver program will process
your request and send you the relevant information. All non-standard mail
requests are routed to CEA personnel who will handle any special requests or
comments. In addition, much of the data described above is also available on
the CEA anonymous ftp site which can be reached at ftp.cea.berkeley.edu.
Again, the Archive group is working hard to provide useful data, services and
documentation to the astronomical community and would appreciate any comments
and/or suggestions for improvement.
6. CEA Job Listings
===================
by Cathie Jones, CEA Personnel Manager
Management Services Officer
Independently manage all business functions for the Center for EUVE Astro-
physics. Oversee the development and implementation of the following areas:
accounting, human resources, editorial services, contracts and grants admini-
stration, public relations, purchasing, facilities management and office
management. Financial analysis, budget and manpower planning required. Su-
pervisory and managerial experience required, preferably in a research envi-
ronment with hands-on project responsibility. Government contract negotiation
skills desired. UC experience in financial and personnel administration
helpful. Salary $37800 - $47200. EEO/AA.
For additional information, call Cathie Jones at (510) 642-1263.
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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. Publishers:
Drs. R. Malina and C. Stuart Bowyer. Editor: B. Stroozas. Funded by
NASA contracts NAS5-30180 and NAS5-29298. Send newsletter correspondence
to: ceanews@cea.berkeley.edu. The EUVE Public Science Archive is available
via FTP: ftp.cea.berkeley.edu, pub/archive. The EUVE project is
managed by NASA's GSFC. The GSFC Project Manager: Paul Pashby, Project
Scientist: Dr. Yoji Kondo, Deputy Project Scientist: Dr. Ronald Oliversen.
NASA HQ Program Scientist: Dr. Robert Stachnik, Dep. Program Scientist:
Dr. D. Buzasi, Program Manager: Dr. G. Riegler. GSFC Project Operations
Director: Mr. Kevin Hartnett. Information on the EUVE Guest Observer
Program is available from: Dr. Y. Kondo, Mail Code 684, GSFC, Greenbelt,
MD 20771 (301)286-6247; e-mail to euve@stars.SPAN.NASA.GOV.
END-----EUVE---------ELECTRONIC---------------NEWS-----------------END
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