HEADNEWS: THE ELECTRONIC NEWSLETTER OF THE
HIGH ENERGY ASTROPHYSICS DIVISION OF THE AAS
|
Newsletter No. 80, May 2002 |
- Notes from the Editor - Matthew Baring
- Chandra Telescope Designer Wins 2002 Rossi Prize - Megan Watzke
- Second Schramm Prize Awarded to Naeye for Chandra Article - Christopher Wanjek and Lynn Cominsky
- HEAD in the News - Lynn Cominsky, Ilana Harrus,
and Megan Watzke
- News from NASA Headquarters - Paul Hertz, Lou Kaluzienski and Don Kniffen
- Chandra Fellows Named - Nancy Evans
- GLAST Mission News - Lynn Cominsky
- Swift Mission News - Lynn Cominsky
- RXTE News - Padi Boyd, et al.
- RHESSI Mission News - David Smith
- FUSE Returns from the Brink - Bill Blair
- HETE Mission News - George Ricker
- Chandra X-ray Observatory Operations Report - Roger Brissenden
- Meeting Announcements:
from the Editor - Matthew Baring, HEAD Secretary-Treasurer,
headsec@aas.org, 713-348-2983
HEAD only delivers the table-of-contents for HEADNEWS into your mailbox. The newsletter itself can be found online at http://www.aas.org/head/headnews/headnews.may02.html.
The next HEAD Division meeting is to be held in Mt. Tremblant,
Canada in the mountains near Montreal from Sunday March 23rd, 2003 till
Wednesday, March 26th 2003. This conference, to be hosted by McGill
University, will revert to the normal HEAD meeting format, contrasting
the recent joint meeting with the APS Division of Astrophysics (DAP) in
Albuquerque, NM. The meeting will include invited and contributed
talks, poster sessions, and afternoon/evening workshops as in recent
HEAD meetings. Stay tuned for more information in the Fall; updates
will be emailed to the membership as well as posted on the HEAD web
site: http://www.aas.org/head/.
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2. Chandra Telescope Designer Wins 2002 Rossi Prize -
Megan Watzke, Chandra Press Officer
Leon Van Speybroeck of the Harvard-Smithsonian Center for Astrophysics
in Cambridge, Massachusetts has been awarded the 2002 Bruno Rossi Prize
of the High Energy Astrophysics Division of the American Astronomical
Society. The prize includes an engraved certificate, a $1,500 award and the
opportunity to give the prize lecture at the next winter meeting of the AAS.
Van Speybroeck, who led the effort to design and make the X-ray mirrors
for NASA's premier X-ray observatory, the Chandra X-ray Observatory, was
recognized for a career of stellar achievements in designing precision
X-ray optics. As Telescope Scientist for Chandra, he has worked for
more than 20 years with a team that includes scientists and engineers
from the Harvard-Smithsonian, NASA's Marshall Space Flight Center, TRW,
Inc., Hughes-Danbury (now B.F. Goodrich Aerospace), Optical Coating
Laboratories, Inc., and Eastman-Kodak on all aspects of the X-ray mirror
assembly that is the heart of the observatory.
"Leon is one of the master mirror designers of our time," said Harvey
Tananbaum, director of the Chandra X-ray Center. "His contributions
were crucial to the spectacular success of the Chandra mission."
The Chandra mirrors are the most precise mirrors ever made, smooth with
tolerances of a few atoms. If the state of Colorado had the same
relative smoothness as the surface of the Chandra X-ray Observatory
mirrors, Pike's Peak would be less than an inch tall. The smoothness and
alignment of the Chandra's mirrors are enabling scientists to make new
discoveries about black holes, neutron stars, and galactic explosions.
"Many, many other people made essential contributions to the Chandra
program, and hopefully some of them will receive proper recognition,"
said Van Speybroeck. "In the meantime, I am thoroughly enjoying my days
in the sun, but quite humbled by the list of past recipients."
Van Speybroeck, a graduate of the Massachusetts Institute of Technology,
once took a course in optics under Rossi, but his thesis work was in
high-energy physics. Upon graduation, he joined the X-ray astronomy
group at American Science & Engineering and became involved in the
design of the X-ray mirrors for NASA's Skylab project. After moving to
the Harvard-Smithsonian Center for Astrophysics, he had primary
responsibility for designing and developing the mirrors for the Einstein
X-ray Observatory, the predecessor of the Chandra X-ray Observatory.
For a picture of Van Speybroeck and more information on the Chandra
X-ray Observatory, go to http://chandra.harvard.edu.
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3. Second Schramm Prize Awarded to Naeye for Chandra Article
- Christopher Wanjek and Lynn Cominsky
The winner of the 2002 David N. Schramm Award for high-energy
astrophysics science journalism proved to be more powerful than a
locomotive with an article comparing Superman and the Chandra X-ray
Observatory. Robert Naeye captured top honors for an article he
published in the journal California Wild, entitled "Superman's
Telescope."
Naeye, who is the editor of Mercury, the magazine of the
Astronomical Society of the Pacific, received the $1,500 cash prize and
a plaque honoring his achievement at the joint APS/DAP - HEAD meeting
in Albuquerque in April. The award was presented by HEAD Chair Josh
Grindlay and Schramm committee chair Lynn Cominsky, at the end of a
special awards session during the meeting. Naeye also received travel
expenses to the meeting, and the publisher of California Wild received
a certificate honoring the work.
Naeye's article takes the reader through the history of X-ray
astronomy, a world in which "photons punch right through normal mirror
surfaces just like bullets zipping through Kleenex tissues," he wrote.
The article also tells the tale of the Chandra X-ray Observatory: a
25-year saga in which the telescope fell victim of countless budget
cuts and delays, yet, upon launch in 1999, now rivals the Hubble Space
Telescope with its discovery potential.
"It's an honor to win this award, especially because it is named
after one of the great physicists of our age," said Naeye, who is also
the author of the book for junior high school students "Signals from
Space: The Chandra X-ray Observatory," published by Raintree
Steck-Vaughn in 2000. "I thank my editors at California Wild, Kathleen
Wong and Keith Howell, and the thousands of people who made Chandra a
reality, giving me such an exciting topic to write about."
California Wild is a quarterly magazine published by the California
Academy of Sciences. Naeye's article appeared in the Summer 2001 issue
and can be viewed online at
http://www.calacademy.org/calwild/summer2001/stories/chandra2sl.html.
The HEAD journalism award is named in memory of David Schramm of the
University of Chicago, a world leader in theoretical astrophysics and a
leading authority on the Big Bang model of the formation of the
universe. He was killed in 1997 when the twin-engine plane he was
piloting crashed outside of Denver. Schramm was dedicated to public
outreach, and the HEAD writing award that bears his name recognizes
distinguished writing on high-energy astrophysics that improves the
general public's understanding in and appreciation of this exciting
field of research.
HEAD presents the Schramm award at least every 18 months at its
division meetings. Entries are judged by a committee of distinguished
scientists and journalists selected by the HEAD Executive Committee.
Information about the prize is available at
http://www.aas.org/head/schramm/schramm.prize.html.
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4. HEAD in the News (November 2001 - May 2002) -
Lynn Cominsky, retiring HEAD Press Officer, Ilana Harrus,
new HEAD Press Officer, and
Megan Watzke, Chandra Press Officer
HEAD news coverage continued to increase during the past six months.
We had coverage in the New York Times, the Washington Post, USA Today
and many spots on the internet, television and radio. Here are some
of the highlights.
NEWS from the AAS Meeting in Washington DC (January 2002)
During this meeting, Chandra had two major stories that were both
featured in press conferences.
The first was the work by Brian McNamara (Ohio University) et al. on
the Abell 2597's so-called ghost cavities, vast regions containing
almost no X-ray or radio emission. These are believed to be the relics
of an ancient eruption that tore through this cluster of galaxies.
(See ApJ 562, L149 or
http://chandra.harvard.edu/press/02_releases/press_010802.html)
The next day, Daniel Wang (U Mass) et al. unveiled their Chandra
mosaic of the galactic center, one Chandra's most striking images to
date. The galactic center story made the front page of USA Today, LA
Times, Science News and received heavy coverage in many other media
outlets. See commentary by Andreas Eckert in Nature 415, 128 -129, Wang
et al. in Nature 415, 148 - 150 and
http://chandra.harvard.edu/press/02_releases/press_010902.html.
Other HEAD related press releases featured at this meeting included
"The Big Glitcher pulsar PSR J0537-6910" by Frank Marshall (NASA/GSFC)
et al., "Evidence of a black holes missing link" by Joel Bregman (U
Michigan) et al. which was written up in Science by Govert Schilling
Volume 25; 295: p. 616, "Astronomers try to Catch a Runaway Star SGR
1900+14" by Kevin Hurley (UCB) et al., "Seven pulsars discovered in
Neighbouring Galaxy" by Silas Laycock (U Southampton) (A&A, v.385,
p.464) and "Newly Discovered Sub-class of "Local" Gamma-ray Bursts May
Solve a Mystery or Two" by Jay Norris (NASA/GSFC).
Joint HEAD/APS Division of Astrophysics Meeting in Albuquerque (April 2002)
The website for the press at this HEAD meeting can be found at:
http://charmian.sonoma.edu/head2002.
The potential explanation for the existence of Ultra High Energy
Cosmic rays was presented at a press conference held on Sunday, April
21. Correlating optical data with events from the Akeno Giant Air
Shower Array (AGASA) near Yamanashi, Japan, Elihu Boldt (NASA/GSFC) et
al. identified old quasars as possible sites of the acceleration of
these highly energetic particles (above 100 EeV). Masahiro Teshima
presented the results from the AGASA team, and Michael Cherry
(Louisiana State University) provided commentary. This result was
reported by MSNBC, the BBC, The Dallas Morning News, Science, New
Scientist and several other media outlets. On the Web: http://xxx.lanl.gov/ps/astro-ph/0204419/.
The final version of the paper is to appear in Physical Review D.
Later on Sunday, Michael Turner (Chicago) did a short presentation
to the press and a much longer Q&A with the media about recommendations
in Phase II of the "Turner Report" the National Academy of Sciences
study from the Committee on the Physics of the Universe entitled
"Quarks to the Cosmos." His entire presentation can be both viewed and
downloaded from the HEAD press website listed above. The report itself
is at: http://www.nationalacademies.org/bpa/projects/cpu/report/.
This press conference was jointly sponsored by HEAD and the APS.
Millisecond pulsars were the stars (so to speak) of the press
conference held on Monday, April 22. Craig Markwardt (Univ. of
Maryland/GSFC) described a newly discovered binary system in which the
companion star has all but disappeared (only 14 times as massive as
Jupiter) and Todd Strohmayer (NASA/GSFC) described a superburst
observed in another millisecond pulsar binary system, which provides
the best evidence to date that the pulsations seen within the burst
originate from the neutron star's spin. The article has recently been
accepted by ApJ and can be found at: http://xxx.lanl.gov/ps/astro-ph/0205435/.
MIT's Deepto Chakrabarty provided the independent commentary. Both
discoveries were made using the Rossi X-ray Timing Explorer, and
received coverage in several space and science publications including
Science, Science News , and Sky and Telescope.
On Tuesday, April 23, the HEAD press conference dealt with X-ray
flashes and their link to gamma-ray bursts. John Heise (SRON) and
Marc Kippen (LANL) each presented their latest results and their
consequences for the interpretation of this relatively newly
discovered phenomenon. Heise showed data from Beppo-SAX, while Kippen
correlated Beppo-SAX data with that from CGRO/BATSE. Bing Zhang (Penn
State University) provided the independent commentary.
We also issued several printed press releases, some of which got
some significant press coverage. Jon Miller (MIT) had an interesting
result, using data from XMM-Newton, showing evidence for a spinning
black hole pumping energy into its surroundings. The story was covered
by Space News. Read more about it at: http://sci.esa.int/content/news/index.cfm?aid=23&cid=45&oid=29877
or in ApJL 570, p. L69-L73.
Demos Kazanas (NASA/GSFC) presented a new theory on cosmic ray
energy losses occurring when they penetrate the Earth's atmosphere.
Kazanas suggests that the missing energy could potentially creates tiny
black holes or being transferred to gravitons which then escape to
other dimensions. The story was picked up by UPI and several space-related
media outlets.
A press release was issued describing the research of a team of
astronomers led by David Clements (Imperial College) who used
Chandra's observations of Arp 220 to study the head-on collision of
two Milky Way-like galaxies.
Also at the HEAD meeting, Leisa Townsley (Penn State) and her
colleagues released their spectacular X-ray image of 30 Doradus, one of
the most active star-forming regions in our Local Group of galaxies.
On the Web: http://chandra.harvard.edu/press/02_releases/press_041902.html
http://chandra.harvard.edu/photo/2002/0057/index.html.
Finally, a non-publicized result from Arnold Rots (CfA) on a
possible planetary system around a pulsar was written about by USA
Today.
News from Chandra:
Strange Quark Stars:
In April 2002, Chandra held a Space Science Update at NASA HQ in
Washington, DC, that presented work by Jeremy Drake
(Harvard-Smithsonian Center for Astrophysics) et al. that the data from
RXJ1856.5-3754 could support evidence for quark star matter. Also
presented were results from Patrick Slane (Harvard-Smithsonian Center
for Astrophysics) and David Helfand (Columbia University) that 3C58 is
unusually cold suggesting exotic cooling processes. The SSU received
a great amount of interest from the press nationally and worldwide, and
made the front pages of the New York Times, San Diego Tribune, and
Orlando Sentinel. On the Web: article by Charles Seife in Science 2002
April 12; 296: 238, Slane et al. ApJ 571, L45 and the press release:
http://chandra.harvard.edu/press/kits/strangematter/.
Venus and Jupiter:
Two separate releases were issued during the past
six months on objects in our Solar System, both garnering significant
public interest. The discovery of X-rays in Chandra observations of
Venus, made by Konrad Dennerl (Max Planck Institute for
Extraterrestrial Physics), were announced in a press release on
11/29/01 (see also Dennerl et al. A&A, v.386, p.319.) In late
February, a press release was issued regarding Chandra's discovery of
a pulsating hot spot in the polar regions of Jupiter by Gladstone et
al. (Nature 28 Feb 2002 v. 415, p. 1000). On the Web:
http://chandra.harvard.edu/press/01_releases/press_112901.html,
http://chandra.harvard.edu/press/02_releases/press_022702.html.
Double Bonus with a Distant Quasar:
Chandra pulled double duty with
quasar PKS 1127-145. One team, led by Aneta Siemiginowska
(Harvard-Smithsonian Center for Astrophysics) used it to discover a
previously unknown jet of a million light years (Siemiginowska et al.
ApJ 570, 543). Jill Bechtold's group (University of Arizona) used
PKS 1127-145 to study an intervening galaxy and determine it had just
one-fifth the oxygen measured for typical stars in the Milky Way
(Bechtold et al. ApJ 562, 133). See also the press release at:
http://chandra.harvard.edu/press/02_releases/press_020602.html.
The Three Highest-Redshift Quasars:
Pushing further back toward the first generation of objects to form in
the Universe, Chandra observed the three most distant known quasars
(z=5.82, 5.99, and 6.28) and found them to be prodigious producers of
X-rays. The quasars were first discovered in optical wavelengths by
the Sloan Digital Sky Survey, and then observed by Chandra with
Director's Discretionary Time proposed by Niel Brandt (Penn State
University). See the press release at:
http://chandra.harvard.edu/press/02_releases/press_032802.html.
To see all the Chandra news releases, check out http://chandra.harvard.edu/press/.
News from XMM-Newton
XMM-Newton news continues to increase as their observing program
progresses. Here are some releases of interest:
ESA's X-ray Space Telescope Proves Supernova can cause Mysterious
Gamma-ray Bursts:
By analyzing the afterglow of the gamma-ray burst GRB 011211 in X-ray
light, scientists produced the first ever evidence of the presence
of chemical elements which were the unmistakable remnants of a
supernova explosion which had occurred just a few days before.
Originally spotted by Beppo-SAX, XMM-Newton obtained follow up
observations 11 hours after the GRB trigger. See Reeves et al. Nature,
Volume 416, Issue 6880, p. 512, the commentary by Herman Marshall in that
same issue of Nature and the article by Govert Schilling in Science on
2002 April 5; v. 296, p. 41.
Mapping the Ingredients of an Exploded Star:
Probably the most detailed analysis of the composition and dynamics of
the supernova remnant Cassiopeia-A were published as elemental maps by
Willingale et al. (A&A v.381, p.1039) using data from XMM-Newton's
EPIC-MOS camera. In these maps, the distributions of silicon, sulphur,
argon and calcium -all oxygen burning products- are similar and
distinct from the carbon burning products, neon and magnesium. Iron
abundance is seen to vary over the remnant with little correlation to
other elements. The study also determined the Doppler velocities of the
various elements. Iron, produced at the heart of the stellar explosion
and present now in the furthest reaches of the remnant, was apparently
expelled considerably faster to overtake other elements.
For more about XMM-Newton news, see
http://sci.esa.int/xmm/.
Other News
Scientists Detect First Afterglow of Short Gamma-ray Bursts:
Scientists say they have detected for the first time a lingering
afterglow of the shortest types of bursts, which themselves disappear
within a second. Davide Lazzati and Enrico Ramirez-Ruiz (Institute
for Astronomy, Cambridge, UK), along with Gabriele Ghisellini
(Osservatorio Astronomico di Brera, Merate, Italy), published these
results in a recent issue of Astronomy & Astrophysics, 379, L39. They
summed the data from 76 short bursts seen by the BATSE on board CGRO,
to see the elusive afterglow in hard X-ray emission using the same
detectors. Also see:
http://www.ast.cam.ac.uk/~lazzati/short/short.html.
Gamma-ray Bursts are Caused by Explosive Death of Massive Stars, New
Study Reveals:
Careful observations of gamma-ray burst GRB 011121 by
Kulkarni et al. have uncovered remnants of the exploded star, along
with two compelling tell-tale signatures: the data show that a
supernova accompanied the burst and the explosion took place in a
cocoon of gas fed by a "wind" of matter emanating from the progenitor
star. To appear in ApJL (2002).
X-rays Limit Mass of Neutrino Dark Matter:
A team of scientists at the University of California, San Diego has
used data from X-ray telescopes to set a limit on the characteristics
of a possible dark matter candidate sterile neutrinos. In a paper
published in the December 1 issue of the Astrophysical Journal by
Abazajian et al. (v. 562, p. 593), the scientists show that the decay
of sterile neutrinos would produce a sharp peak in the X-ray spectrum
from the hot gas clouds present in galaxy clusters. The predicted
height of the peak in the spectrum increases with the assumed mass of
the sterile neutrino.
Music of the Black Holes: They All Play the Same Tune:
Astronomers at the University of Southampton have uncovered a
remarkable connection between the monstrous black holes residing at
the hearts of distant galaxies and their comparatively tiny cousins
which inhabit star systems in our own Milky Way: they are playing the
same tunes. Using the Rossi X-ray Timing Explorer, the scientists
have found that the time-scales for variations seen in the power
spectra are about a million or more times longer in active galaxies
than in BHXRBs. See Uttley et al. MNRAS v. 332, p. 231.
Press Officer News:
This column marks the final contribution as HEAD Press Officer from
Lynn Cominsky, who has now officially turned over the duties to Ilana
Harrus. Harrus worked with Cominsky throughout the April HEAD
meeting, and assumed control of the final two press briefings. Thanks
to everyone in HEAD for your support of the press activities during
the last six years. It has made a big difference in the media's
awareness and in the public perception of our science. Cominsky is
continuing to support the AAS as Deputy Press Officer, and also will
continue to serve as Press Officer for both Swift and GLAST.
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5. News from NASA Headquarters -
Paul Hertz, Lou Kaluzienski and Don Kniffen, NASA Headquarters.
President's FY03 budget
The budget submitted by President Bush in January 2002 to the
Congress for fiscal year 2003 (FY03) continues the recent trend of
increased funding for NASA space science. A top level synopsis of
major changes from the current budget includes:
- An increase in the Office of Space Science (OSS) 5-year budget of $682M;
- The addition of a Nuclear Systems Initiative to add radioisotope
thermal generators to the 2009 Mars rover and to research nuclear
electric power and nuclear electric propulsion for deep space
missions;
- The cancellation of the last remaining mission in the Outer Planets
Program, the Europa Orbiter mission;
- The creation of a New Frontiers Program for moderate ($650M),
PI-class planetary missions;
- The transfer of the Deep Space Network into OSS;
- Support for SM-4 as the final Hubble servicing mission and the
increase of funding for NGST as funding for Hubble decreases in the
post-servicing era.
Detailed analyses of the NASA budget are usually done by the AAS and
the AIP. Please check their web sites for more details.
OSS Strategic Plan and SEU Roadmap
NASA is required by law to update its strategic plan every three
years. In support of the NASA strategic plan, OSS is updating its
strategic plan. The contents of the OSS strategic plan will be set at
a meeting of the Space Science Advisory Committee in November 2002; the
plan will be published in 2003. The 2003 OSS strategic plan will be
based on roadmaps prepared this year by each of the OSS science
themes.
Most high energy astrophysics falls within the Structure and Evolution
of the Universe (SEU) science theme within OSS. The SEU roadmap is the
responsibility of the SEU Subcommittee (SEUS), and the SEUS has
appointed a Roadmap Team to actually write the roadmap. At its April
meeting, the SEUS decided on the outline of the SEU roadmap, and the
contents of the SEU roadmap will be the discussed and decided upon at
the August meeting.
The SEU roadmap will draw heavily upon community input. This input
includes National Academy of Sciences surveys (e.g. Decadal Survey
(McKee-Taylor Report), Committee on Physics of the Universe (a.k.a.
Turner Committee) Report), white papers solicited from the broad SEU
community, NASA sponsored and grass roots workshops and working groups,
etc. The report will also draw upon the 1999 SEU Roadmap which was the
outcome of a year of work by 9 discipline working groups.
The roadmap will identify two science programs which capture the
highest science priorities within SEU. The first program, called
"Beyond Einstein", will focus on science goals related to the nature of
space and time. Constellation-X and LISA are identified as the highest
priority missions to address these science goals. The second program,
tentatively called "Cycles of Matter and Energy", will focus on science
goals related to the formation of structure, nucleosynthesis, and the
evolution of the contents of the universe.
The final roadmap will be completed by September and published in
November. Progress may be monitored at http://universe.gsfc.nasa.gov/roadmap.
Explorer Selections
Selections for concept studies in the Medium-class Explorer (MIDEX) Program were announced on April 17. Four MIDEX missions and one mission-of-opportunity (MO) were selected for study. These missions are:
- The Astrobiology Explorer (ABE), PI: Scott Sandford, NASA/Ames. A
cryogenic telescope and high resolution infrared spectrometer to
measure interstellar organic compounds and determine the abundance,
distribution and identities of the chemical building blocks of life.
- The Next Generation Sky Survey (NGSS), PI: Ned Wright, UCLA. A
cryogenic telescope designed to conduct an all-sky 4-color mid-infrared
survey with 1,000 times more sensitivity than previous missions.
- The Time History of Events and Macroscale Interactions during
Substorms (THEMIS) mission, PI: Vassilis Angelopoulos, UC Berkeley. A
study of the onset of magnetic storms within the tail of the Earth's
magnetosphere which would fly five microsatellite probes through
different regions of the magnetosphere and observe the onset and
evolution of storms.
- The Advanced Spectroscopic and Coronagraphic Explorer (ASCE), PI:
John Kohl, SAO. A solar coronagraph and high resolution spectrometer
that would reveal the physical processes in the outer atmosphere of the
Sun leading to the solar wind and explosive coronal mass ejections.
- US Participation in the Extreme Universe Space Observatory (EUSO),
PI: Jim Adams, NASA/Marshall. An ESA mission to study the highest
energy cosmic rays from the International Space Station.
A downselection for flight among these missions is expected in March
2003. In other Explorer Program news, a downselect among the Small
Explorer (SMEX) missions current conducting concept studies is expected
in early July 2002, and the next SMEX Announcement of Opportunity (AO)
is planned for the first quarter of 2003. Information on the MIDEX
concept studies may be found at
http://spacescience.nasa.gov/midex/
and on the SMEX concept studies at
http://spacescience.nasa.gov/smex/ .
Senior Review of Astrophysics Missions
NASA will hold its biennial review of operating astrophysics
missions on June 11-13, 2002. This review will evaluate and prioritize
the science value in continuing science operations of seven missions
which have, or will have by the end of FY04, completed their prime
missions: 2MASS, FUSE, HETE-2, MAP, RXTE, SWAS, XMM-Newton (US
participation only). NASA has a limited budget for mission operations
and data analysis. Each mission's science team, and often the user
community, has proposed the science which could be accomplished with
continued operations. The Senior Review panel is a community peer
review panel made up of experienced, senior members of the broad user
community. NASA will use the findings, priorities, and recommendations
of the Senior Review panel to allocate these funds with the goal of
optimizing the science return for the community. NASA also uses the
Senior Review report as the principal input in decisions to terminate
missions when their science return decreases. The reports of previous
Senior Reviews may be found on the Astronomy and Physics Division
Homepage at
http://spacescience.nasa.gov/admin/divisions/sz/.
Astronomy and Physics Working Groups
Two new working groups have been established to provide input on NASA's Astronomy and Physics program to the two Astronomy and Physics advisory committees (Origins Subcommittee and SEUS). These working groups are the Astronomy and Physics Working Group (APWG, chaired by Doug Richstone, U. Michigan) and the Science Archives Working Groups (SAWG, chaired by Joel Bregman, U. Michigan). Both working groups had their first meetings in April 2002. The APWG is chartered to look at the research and analysis (R&A) programs within astronomy and physics. The SAWG is chartered to look at NASA's astronomy and physics science data program including data centers and data archives. The reports of both working groups will be posted on the Astronomy and Physics Division Homepage at
http://spacescience.nasa.gov/admin/divisions/sz/.
Proposal Deadlines
Anticipated proposal deadlines for the remainder of 2002 (and early 2003) include:
- ADP/LTSA - July 10, 2002
- ATP - August 30, 2002
- RXTE Cycle 8 - September 2002 **
- HST Cycle 12 - September 2002 **
- FUSE Cycle 4 - October 2002 **
- Chandra Cycle 5 - Early 2003 **
- SMEX - May 2003 **
** denotes call for proposals not released yet, date could change.
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6. Chandra Fellows Named - Nancy Evans
The Chandra X-ray Center is pleased to announce the new Chandra Fellows
for 2002:
- Ann Hornschemeier from Penn State will be a Fellow at Johns Hopkins
- Julia Lee from Cambridge will be a Fellow at MIT
- Eric Pfahl from MIT will be a Fellow at Harvard
- Anatoly Spitkovsky from Berkeley will be a Fellow at Berkeley
- Licia Verde from Edinburgh will be a Fellow at Princeton
The competition for 2003 Fellows will be held this fall, with
proposals due in mid-November. The announcment of opportunity (AO)
giving the details of the program will be updated in the summer.
However, the previous AO is available from: http://cxc.harvard.edu/fellows/Chandra_fellow.2002.summer.html.
The Annual Chandra Fellows Symposium will be held Oct. 7, 2002 at the
Harvard-Smithsonian Center for Astrophysics, where interested people
can hear what the Chandra Fellows have been doing. Further details can
be found from the website above.
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7. GLAST Mission News -
Lynn Cominsky, GLAST Press Officer
In January, NASA and the Department of Energy (DOE) signed the
Implementing Arrangement concerning cooperation on the GLAST Mission.
The signing of this agreement establishes the roles of DOE and NASA in
their joint sponsorship of the Large Area Telescope (LAT). Agreements
with international partners are now in progress.
The GLAST project has undergone two major reviews during the past 6
months. The joint NASA/DOE PDR/Baseline review for the LAT was held in
early January, 2002. The LAT passed the PDR, however changes to the
mechanical/thermal sub-system will be needed to accommodate the
spacecraft. This sub-system will be reviewed in a "delta-PDR" in late
July. The PDR for the GLAST Burst Monitor (GBM) was held in February.
Review teams from both GSFC and MSFC participated. The consensus of
the review teams was that the GBM design is at or beyond PDR level. No
areas of concern surfaced that indicated substantial programmatic or
technical risk. The spacecraft RFO was released in mid-May with vendor
selection expected in August. The GLAST launch is now scheduled to
occur in September 2006.
There were several key personnel changes on the GLAST project,
including a new project manager at GSFC, Elizabeth Citrin, and the
addition of a LAT Deputy Project Manager at SLAC, Jim Martin. Under the
management of Jay Norris, staffing for the GLAST Science Support Center
is ramping up: David Band is leading the scientific effort, and Dave
Davis is also on the SSC staff at GSFC. Yasushi Ikebe, Masaharu
Hirayama, and Dirk Petry are expected to join the GLAST SSC later this
summer.
A GLAST Science Working Group meeting was held at UC Santa Cruz in
December. This meeting included a special workshop on pulsars,
organized by GLAST InterDisciplinary Scientist (IDS) Stephen Thorsett
(UCSC). The next face-to-face science team meeting will be in
Huntsville, Alabama in late September, hosted by the GBM team.
E/PO News: The GLAST Active Galaxies poster was finished, and has
been widely distributed. Over 5000 have been handed out so far, most in
kits of materials developed for the SEU Forum, entitled "Seeing and
Exploring the Universe." These kits were big hits at the ITEA, NSTA and
NCTM national meetings of technology educators, science teachers and
mathematics teachers. A workshop on GLAST science by Cominsky and
Ambassador Mike Ford was also held at the National Science Teacher's
Association meeting The GLAST movie has also been released, and can be
viewed through a link on the home page of the newly redesigned EPO web
site: http://glast.sonoma.edu. GLAST mission trading cards have also
been printed. The GLAST card is one of five mission cards that are part
of the Cosmic Journeys card game, which will soon be available for
distribution. The GLAST booth made appearances at local and national
meetings such as the January AAS in DC, and the Expanding Your Horizons
conference, held at SSU in March, that was attended by ~500 7th and 8th
grade girls. A poster on the GLAST Telescope Network was presented at
the January AAS meeting by Mattox, Cominsky and Spear. The GBM is
contributing to the GLAST EPO effort by providing support to a
High-Energy Astrophysics Workshop for Amateur Astronomers. The
workshop will be held in conjunction with the 91st Spring Meeting of
the AAVSO in Kona, Hawaii on June 30 July 6.
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8. Swift Mission News -
Lynn Cominsky, Swift Press Officer
The team behind the NASA gamma-ray burst satellite called Swift has
completed construction of a massive "coded aperture mask," the largest such
device ever built, marking another milestone on its path to a September
2003 launch. The mask, the size of a standard piece of plywood (4 by 8
feet, or 1.2 by 2.4 meters), comprises approximately 52,000 tiny lead
squares spaced in a computer-generated random pattern.
"Each of the 52,000 tiles was hand-placed 'upside down,'" said Danielle
Vigneau, the lead engineer for the team that designed and built this coded
aperture mask at NASA Goddard Space Flight Center. "We then used a thin
coat of wet adhesive to bond all of the tiles to
the panel simultaneously as the panel was lowered down on top of the tiles."
The mask together with a set of gamma-ray detectors, totaling 32,768 pieces
of cadmium-zinc-telluride each measuring four square millimeters are the
main components of Swift's Burst Alert Telescope (BAT). BAT will locate
hundreds of bursts to better than 4-arcminute accuracy and provide enhanced
sensitivity to faint bursts that earlier detectors have missed. The Swift
team is now preparing for environmental tests of the BAT components,
including a vibration test of the coded aperture mask.
The mission also includes narrow-field x-ray and UV/optical telescopes,
being developed in the UK, Italy and at Penn State University. Both of
these instruments are nearing completion for delivery to Goddard this summer.
The spacecraft is being developed by Spectrum Astro. The pre-ship review
for the spacecraft will be held in late July. The operations readiness
review is planned for late August.
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9. Rossi X-ray Timing Explorer News -
Padi Boyd, Keith Jahoda, Craig Markwardt, Alan Smale, Evan Smith,
Tod Strohmayer and Jean Swank, NASA's Goddard Space Flight Center
The Rossi X-ray Timing Explorer (RXTE) is now well into its 7th
observing cycle and continues to perform well. Operations of all
instruments remain stable. Exciting science results continue to be
generated both from new observations as well as from the extensive RXTE
public archive. RXTE continues to support multi-wavelength efforts, as
well as coordinated observing with the imaging and high spectral
resolution capabilities of Chandra and XMM/Newton. For example, through
AO7 RXTE has carried out about 3.3 Msec of coordinated observing with
these observatories. A few short snapshots of recent RXTE science
highlights follows.
It took a little more than two years for RXTE to discover the first
accreting millisecond pulsar (SAX J1808.4-3658). Recently, within the
space of a month, RXTE has found two more of these ultra-compact
systems, cementing the connection between accreting neutron stars and
millisecond radio pulsars. In early April, 2002 Craig Markwardt
(UMD/GSFC) discovered the 435 Hz pulsar XTE J1751-305 in his twice
weekly Galactic Bulge monitoring campaign with the PCA (IAUC 7867).
Pulse timing analysis revealed a 42 minute binary orbital period and a
minimum companion mass of only 0.015 Solar masses, barely 15 Jupiters.
The X-ray outburst from this system lastest only 10 days. This
discovery received substantial press attention at the recent APS/HEAD
meeting in Albuquerque, NM. For more details, follow the links at
http://heasarc.gsfc.nasa.gov/docs/xte/xhp_new.html#cm_pulsar.
Only a few weeks later, Ron Remillard (MIT) and his colleagues
discovered a new X-ray transient, XTE J0929-314, with the RXTE ASM
(IAUC 7893). Subsequent pointed observations with the PCA revealed this
new source to be a 185 Hz pulsar. These findings triggered additional
TOO observations led by Duncan Galloway (MIT). Galloway and his
colleagues found a 43 minute orbital period for the system and an even
lower mass companion (about 10 Jupiters) than for XTE J1751-305 (IAUC
7900). More details and press information can be found at
http://web.mit.edu/newsoffice/nr/2002/pulsars2.html.
In a related discovery, Tod Strohmayer (NASA/GSFC) and Craig
Markwardt (UMD/GSFC) reported evidence for a millisecond pulsar in the
LMXB 4U 1636-53. They found pulsations at 582 Hz during a
``superburst", a powerful 3 hour-long thermonuclear explosion in the
surface ``ocean" of the neutron star. The pulsations were transient,
but lasted long enough to reveal the signature of orbital modulation.
Details of this work can be found at http://xxx.lanl.gov/abs/astro-ph/0205435.
A number of new and recurrent black hole candidates have also been
active over the last few months. SAX J1805.5-2031 (IAUC 7843) remains
active after discovery in March by both BeppoSAX and RXTE PCA scans.
XTE J1908+094 (IAUC 7856) rose gradually in February and continues in
outburst. GX 339-4, which had been off since the high state outburst in
1998, reappeared and reached a very high state, exhibiting
quasiperiodic oscillations, in X-ray and optical, as it did in 1988
GINGA observations. SAX J1819.3-2525 = XTE J1819-254 = V4641 Sgr
remerged from being off since its dramatic disappearance in September,
1999 with X-ray sputters and flares accompanying dramatic optical
variability (IAUC 7906; 7908). Our Galaxy's black hole population
remains very active.
Amongst the BL Lac sources for which RXTE has had monitoring programs
for several years, 1ES 1959+650 has had a dramatic TeV outburst (IAUC
7907; 7903). Observations of Seyfert galaxies are even allowing
behavior like that of microquasars to be discerned (Uttley et al.
MNRAS 2002; Marscher et al. 2002).
Cycle 8 Announcement:
Preparations for the RXTE cycle 8 Guest Observer Program have begun.
We currently anticipate the release of the cycle 8 NRA in mid-June,
2002 with a proposal due date in late September. When finalized,
specific dates will be posted on the Proposals & Tools link on the RXTE
website: http://rxte.gsfc.nasa.gov/.
RXTE Data Analysis and Calibration News:
Everything is in place for the soon to be released HEASoft v5.2
(hitting the streets on or about June 1, 2002). New versions of the
RXTE response matrix generation tools PCARMF, XPCAARF and the wrapper
script PCARSP are included, as is an updated energy-to-channel FITS
file pca_e2c_e05v02.fits. Response matrix improvements include
applicability of the tools to PCU0 for dates after the loss of the
propane layer on May 12, 2000.
The default values of the geometric areas of four of the five PCUs has
changed in the new XPCAARF. This will introduce a step function in
long term monitoring fluxes; to remove this effect, long term programs
will need to be reanalyzed with one consistent set of XPCAARF
coefficients. This release also includes updated software for
background estimation, including a new PCABACKEST which uses the
recently released Combined Models (CM) and records more information
about models used in the headers. In addition, XTEFILT (ie, FCOLLECT
and XTEDERIVE) has been modified to add a new derived quantity,
L6CNTPCU0, to the filter file. This can be used to filter out times
when large flares appear in the background model due to the loss of the
propane layer in PCU0. Details about the use of these new tools will
be included in the HEASoft release notes, and will also appear on the
RXTE GOF recipes pages. See the PCA Digest (http://rxte.gsfc.nasa.gov/docs/xte/pca_news.html)
for useful links and summary information.
The new CM background models incorporate numerous improvements over the
previous versions for both bright and faint sources. A good source of
information about their performance, as well as practical advice in the
use of the models can be found on Craig Markwardt's summary Web page at
http://lheawww.gsfc.nasa.gov/users/craigm/pca-bkg/bkg-users.html.
Back to Top
10. RHESSI Mission News -
David M. Smith, U. C. Berkeley
The Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI)
satellite was successfully launched as HESSI on February 5th and
renamed in March in honor of the late Dr. Ramaty, whose theoretical
work and personal efforts were both vital to its creation and success.
RHESSI is a Small Explorer mission headed by Principal Investigator
Prof. Robert P. Lin of U. C. Berkeley (UCB), and is a joint project of
the Space Sciences Laboratory (SSL) at UCB, NASA's Goddard Space Flight
Center, the Paul Scherrer Institute in Switerland, and other institutions.
RHESSI was launched by an aircraft-borne Pegasus XL rocket from Cape
Canaveral Air Force Station into its desired circular orbit of 600 km
altitude and 38 degrees inclination. As a Small Explorer
mission operating in "PI mode", RHESSI's mission operations are the
responsibility of UCB, and are done via an 11-meter
dish and full operations center at SSL.
RHESSI's primary goal is to understand the mechanisms for the
acceleration, interaction, and energy loss of energetic particles
associated with solar flares. It consists of a 9-detector germanium
x/gamma-ray spectrometer covering 3 keV to 17 MeV, with each detector
sitting below a pair of grids which function as a rotating modulation
collimator (RMC) when the spacecraft spins. The result is imaging
spectroscopy of flares with energy resolution down to 1 keV and
spatial resolution down to 2.3 arcsec. The energy range covers
thermal and non-thermal bremsstrahlung emitted by accelerated flare
electrons as well as gamma-ray lines from nuclear de-excitation, neutron
capture, and positron annihilation due to interactions of accelerated
ions.
Since the RHESSI detectors are unshielded, and every photon is
recorded with its energy and interaction time even when flares are not
in progress, RHESSI functions as a high-energy-resolution, all-sky
detector for non-solar astrophysics.
The first non-solar results from RHESSI were presented at the joint
HEAD/APS meeting in Albuquerque in April. These included a lightcurve
and energy spectrum for a bright burst from the soft gamma repeater
SGR 1900+14 and a spectrum of the extremely rare, bright outburst of
Cyg X-1 reported by Golenetskii et al. (IAUC #7840). Earth occultation
of this event seen by RHESSI also verifies its position as being
consistent with Cyg X-1. Since that meeting, RHESSI has seen several
cosmic gamma-ray bursts (one extending beyond 1 MeV). RHESSI is being
incorporated into the Interplanetary Network (IPN) for triangulation
of cosmic gamma-ray bursts, and has already helped in the prompt
localization of a burst from another soft gamma repeater, SGR 1806-20
(Hurley et al., GCN circular #1391).
In mid-June, the Crab Nebula will enter RHESSI's imaged (solar)
field of view. If all goes well, the team will repoint the spacecraft
for a couple of days to image the nebula from 3-100 keV or more with
resolution down to 2.3 arcsec. Other non-solar projects have begun
to study the 511 keV and 1809 keV lines from the Galactic Center,
cyclotron lines and other spectral features in pulsars, and
monitoring of bright sources using Earth occultation and
detector/detector occultation.
Oral and poster sessions with RHESSI solar results will
be presented at the Solar Physics Division meeting in conjunction
with the full AAS meeting in June, and at the COSPAR meeting in
Houston in October. New RHESSI non-solar results will be presented
at the SPIE meeting "Astronomical Telescopes and Instrumentation"
in Hawaii in August.
All RHESSI data are immediately available to the public; anyone
interested in working on RHESSI science should visit the RHESSI
general web page and the RHESSI data and software center
(http://hessi.ssl.berkeley.edu/ and
http://rhessidatacenter.ssl.berkeley.edu/). Since the data analysis
software is primarily designed to study solar flares, anyone wishing
to use RHESSI for non-solar astrophysics is encouraged to contact the
RHESSI non-solar coordinator, David Smith, at dsmith@ssl.berkeley.edu.
Back to Top
11. FUSE Returns from the Brink - Bill Blair,
FUSE Chief of Observatory Operations
The Far Ultraviolet Spectroscopic Explorer (FUSE) mission has recovered
from a difficult situation and is back in normal science operations
mode. Two of the four available reaction wheels on FUSE malfunctioned
over a two week period in late-2001, leaving the satellite unable to
perform pointed science operations. (Only two of three axes could be
stabilized.) Attempts since that time to restart either of the errant
wheels have not met with success. However, the Science Operations team
at JHU worked closely with engineers at Orbital Sciences Corporation,
NASA-GSFC, and Honeywell Technical Services, Inc., to develop and
test a new control system that placed the Magnetic Torquer Bars (MTBs)
into active service. The new system uses the two remaining reaction
wheels and the MTBs to maintain three-axis control, and provides
sub-arcsecond pointing control in regions where the magnetic control
is stronger than the gravity-gradient disturbances on the satellite.
This new system was uplinked to the satellite in late-January 2002,
just seven weeks after the problem occurred. February was spent testing
the new system and performing science when we could, but since March 1,
2002, we have been back on-line. We continue to develop tools to
make planning easier (there are many complicated, time-variable aspects
to operations now), and we continue to "push the boundaries" of the
stable regions to increase our sky coverage and target availabilities.
This activity will be on-going through the summer. From tests to date,
we are hopeful that pointing capability over the entire sky can be
re-established at a significant level.
FUSE is a NASA Origins mission that performs high resolution (R=20,000)
far-UV (905-1187 Angstroms) spectroscopy of a wide range of astrophysical
objects. It was developed and is operated for NASA by Johns Hopkins
University. The NASA Research Announcement for Cycle 4 of FUSE
observations is expected in July 2002, with proposals due in October.
To learn more about FUSE, visit the following web site:
http://fuse.pha.jhu.edu/
and to read more about the reaction wheel anomaly and recovery,
see Status Reports 52-56 in the Status Report Archive:
http://fuse.pha.jhu.edu/facts/stat_arch.html.
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12. HETE Mission News - George Ricker,
MIT Center for Space Research, Principal Investigator for the HETE Mission
Now in its second year of operation, the High Energy Transient Explorer
(HETE) mission is devoted to the study of gamma-ray bursts (GRBs) using
soft X-ray, medium X-ray, and gamma-ray instruments mounted on a
compact spacecraft. A science team from France, Japan, Brazil, India,
Italy, and the US is responsible for the HETE mission, which was
completed for ~1/3 the cost of a NASA Small Explorer (SMEX). The HETE
mission is unique in that it is entirely "self-contained," insofar as
it relies upon dedicated tracking, data acquisition, mission
operations, and data analysis facilities run by members of its
international Science Team since the launch into equatorial orbit in
October 2000.
A powerful feature of HETE is its potential for localizing GRBs within
seconds of the trigger with good precision (~10') using medium energy
X-rays and, for a subset of bright GRBs, improving the localization to
~30" accuracy using low energy X-rays. Real-time GRB localizations are
transmitted to ground observers within seconds via a dedicated network
of 14 automated "Burst Alert Stations", thereby allowing prompt
optical, IR, and radio follow-up, leading to the identification of
counterparts for a large fraction of HETE-localized GRBs. HETE is the
only satellite that can provide near-real time localizations of GRBs,
and that can localize GRBs that do not have X-ray, optical, and radio
afterglows, during the next two years.
To date, HETE has produced 17 gamma-ray burst (GRB) localizations.
Localization accuracies are routinely in the 4' - 20' range. In
addition, it has detected ~25 bursts from soft gamma repeaters (SGRs),
and >150 X-ray bursts (XRBs).
During the past 8 months the mission has produced 10 localizations,
corresponding to a rate of ~15 per year. (This rate of localizations is
~2 times the rate achieved by the BeppoSAX satellite in its six years
of operations). Four of the 10 recent localizations have yielded
optical afterglows (with 2 redshifts measured so far); one more has
yielded probable X-ray and radio afterglows. Two Chandra Target of
Opportunity (TOO) observations have been carried out based on HETE
localizations. HETE has detected a dozen short (< 2s) duration GRBs.
HETE has also discovered 18 unusually "X-ray rich" GRBs, for which more
than 30% of the energy is emitted in the 2-10 keV band. Of these 18
"X-ray rich" GRBs, 8 have been localized. (In total, HETE has detected
~100 GRBs of all types.)
The spacecraft power system, momentum management, and sun tracking are
working perfectly. During orbit night, the satellite drift rate is now
controlled to ~1"/s. The star camera aspect system provides the actual
pointing direction of the satellite to an accuracy of ~10".
The in-orbit performance of the HETE science instruments has been as
follows-- * FREGATE (French Gamma-Ray Telescope): Completely nominal,
with in-orbit sensitivity about 2x better than pre-launch predictions.
* WXM (Wide Field X-ray Monitor): Hardware performance has been
completely nominal, with in-orbit sensitivity equal to pre-launch
predictions. Optimization of on-board triggering and localization
software has been an ongoing activity. * SXC (Soft X-ray Camera): The
density of atomic oxygen at the altitude of the HETE orbit was >1000
times greater than pre-launch predictions, due to intense solar
activity during the first few months of the mission. This effect led to
erosion of the SXC thin, outer optical blocking filter (a thick inner
filter, which protects only 1/2 of the CCD array, was unaffected by
atomic oxygen). By 5 months post-launch, the consequent light leak
resulted in loss of X-ray sensitivity for 1/2 of the CCD array, and
necessitated a change in the flight software to correct for the
light-induced variable bias level for the other 1/2 of the CCD array. A
software modification, implemented in July 2001, fully restored the SXC
localization precision (<30" at present), as verified by successful SXC
localizations of 9 Galactic transients (produced by 4 X-ray bursters
and 1 soft-gamma repeater) in July-August 2001. The SXC is currently in
observing mode with a sensitivity of 1/sqrt(2) the pre-launch
prediction for 2/3 of each lunar month; SXC observations are not
possible for 4-5 days on each side of full moon because of a residual
light leak. The HETE secondary science goal of soft X-ray observations
below 1.3 keV is also not realizable due to the light leak.
However, despite the recent successes of the HETE mission in localizing
GRBs, the scientific yield from the first year of the HETE mission was
less than had been anticipated. Even now -- with instrumental and
operational challenges overcome -- the GRB localization rate, while
twice the BeppoSAX mean rate of ~9 localizations per year, is ~1/3 the
rate that had been expected for HETE prior to launch. Although 6 SGR
and 27 XRB Wide-Field X-Ray Monitor (WXM) localizations have gone out
in near-real time, no accurate near-real time GRB localizations have
been circulated.
Several factors contributed to the first year problems of the HETE
mission. Difficulties of the kind that most missions experience during
their Performance Verification phase had to be overcome, including
issues involving optical aspect, spacecraft system reboots, an
unreliable Cayenne Primary Ground Station, and implementation and
testing of the sophisticated WXM flight software that localizes bursts.
All of the above problems are now fixed, but because of manpower
shortages in the first year arising from initial underfunding of the
MO&DA effort, fixing them took much longer than had been expected (ie,
~9 months rather than the ~3 months anticipated).
The rate of HETE GRB localizations is lower than was expected prior to
launch due to two factors: 1) a much smaller than expected "live time"
for the instruments; and 2) a lower-than-expected rate of detection of
GRBs by the WXM. It has been necessary to operate FREGATE and WXM only
from terminator to terminator and often only from orbit "dusk" to orbit
"dawn," in order to safeguard the health of these instruments because
of solar activity (solar maximum occurred in January 2001 and an
unexpected secondary maximum has occurred recently). This has reduced
the WXM localization rate by a factor of about 1.5 compared to that
expected prior to launch.
Three additional factors affected the rate: 1) the BATSE GRB rate,
from which we scaled the predicted HETE rate, was reduced by a factor
of 0.82 in the 4B catalog (Paceisas et al 1999); 2) it is becoming
apparent that short GRBs, which have very hard gamma-ray spectra, may
also be X-ray poor; and 3) the average ratio of Lx/Lgamma for GRBs is
lower than was expected. While these three factors -- taken together
-- reduce the expected rate of HETE GRB localizations by a factor of
about 1.9 compared to the rate expected before launch, their
quantification also represents new knowledge about GRBs that has
important implications for future GRB missions. The result of the
lower than expected "live time" and the reduction in the expected
localization rate is a reduction in the HETE GRB localization rate of a
factor of about 1.5 x 1.9 = 2.8 compared to the rate that was expected
prior to launch.
What about the future? With a 2-year extended mission, the 4-year HETE
mission can be expected to produce totals of ~60 localizations, ~25
optical afterglows, and >25 redshifts. The actual numbers are likely
to be larger, as solar activity declines and the "live time" of the
FREGATE and WXM instruments can be safely increased from 40 minutes to
as much as 55 minutes per orbit. There is also every reason to believe
that the HETE mission will soon produce its first near real-time
localization. In addition, the demonstrated sensitivity of the SXC
holds out the possibility for a number of near real-time < 30"
localizations and the detection of X-ray emission lines in the spectra
of a few very bright GRBs. All in all, with the mysteries that still
surround GRBs and the (currently) unique capabilities of the HETE
FREGATE, WXM and SXC instruments, the scientific promise of the
extended HETE mission is great. The extended HETE mission will yield
new knowledge about GRBs and will continue to serve as a means of
developing and testing flight software that is similar to the flight
software for the BAT on the upcoming Swift mission; both will enhance
the scientific productivity of the Swift mission.
The HETE mission should continue addressing basic questions about GRBs
over the next 2.5 years: What are the "X-ray Rich" GRBs? What are
the short GRBs? Are there other, rarer types of GRBs? Why do only
~1/2 of all GRBs have optical afterglows ? Are there GRBs at z>10?
In the near term, during the upcoming June-August 2002 period the
fields-of-view of the HETE science instruments will include the
Galactic Bulge region. Many of the known sources in this region of the
sky are scientifically interesting (i.e., X-ray bursters, SGRs, AXPs).
They will also be useful for further reducing the systematic errors in
the accuracy of the WXM and SXC localizations. Although HETE will
continue to be "tuned" for the detection of GRBs, the number of
"classical" GRBs localized during the June-August period may be
somewhat reduced due to the elevated X-ray background arising from the
ensemble of Galactic Bulge sources. The Galactic Bulge will exit the
HETE FOV in August, allowing sensitive GRB operations to resume away
from the Galactic plane in September.
HETE is a collaboration between NASA; MIT; Los Alamos National
Laboratory, New Mexico; France's Centre National d'Etudes Spatiales
(CNES), Centre d'Etude Spatiale des Rayonnements (CESR), and Ecole
Nationale Superieure de l'Aeronautique et de l'Espace (Sup'Aero); and
Japan's Institute of Physical and Chemical Research (RIKEN) and
National Space Development Agency of Japan (NASDA). The Science Team
includes members from Brazil's Instituto Nacional de Pesquisas
Espaciais, India's Tata Institute of Fundamental Research, Italy's
Consiglio Nazionale delle Ricerche, the University of California
(Berkeley and Santa Cruz), and the University of Chicago.
Ongoing updates and further details are provided by the HETE Mission
Operations Team at the official website:
http://space.mit.edu/HETE/.
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13. Chandra X-ray Observatory Operations Report -
Roger Brissenden, Manager, Chandra X-ray Center, Smithsonian Astrophysical Observatory
Chandra passed its 1000th day of operation on 18 April 2002 and both
the spacecraft and science instruments continue to operate
exceptionally well.
Operational highlights during the last six months have included the
use of an increased momentum unloading threshold intended to reduce
the number of Momentum Unloading Propulsion System firings. The
increased threshold coupled with a new model for predicting momentum
build-up has succeeded in bringing the rate of firings below the
qualification limit - a potentially life-limiting value. Projections
now give 17-20 years before the qualification limit will be reached.
Chandra passed through the 2002 Spring Eclipse season in February with
nominal power and thermal performance, and passed though a 4% lunar
eclipse on May 11 without incident. On January 23 the spacecraft went
to a bright star hold after a long maneuver. The maneuver resulted in
a pointing error of 150 arcsec that exceeded the aspect camera star
search box size of 120 arcsec. The error resulted from the combination
of the specific eigenaxis alignment for the maneuver and a slightly
inaccurate on-board gyro scale-factor and alignment matrix. An updated
gyro scale-factor and alignment matrix is expected to be up-linked in
June. IOn the meantime, all maneuvers are being screened for similar
cases.
The science observing schedule was halted 9 times between November and
May due high levels of solar activity and twice due to unwanted trips
of the radiation monitor fault flag (the cause has been traced to a
subtle interaction related to the timing of radiation belt entry and
exit and has been mitigated by increasing two counter values
on-board). The team continues to monitor the solar activity carefully
because of the impact on ACIS, and has insured that the CTI
degradation over the last 6 months is within expectations. One impact
of the stoppages however, has been to decrease the scheduled observing
efficiency from the expected 70% to 60%. The Mission Planning team
worked very hard to return to science operations as soon as possible
after a solar event, and was also successful in replanning 8 fast-turn
around Targets Of Opportunity.
The processing, archiving and distribution of data have continued
smoothly with the average time from target observation to data
distribution to user remaining about a week. The Chandra archive has
grown to a total size of 2.9TB and is growing at 0.5TB/year. A
web-based interface to the archive, ChaSeR, was released in December.
Observations for Cycle 3 are in full swing, and over 800 cycle 4
proposals were received by the deadline on March 15. The Peer Review
is scheduled for June 18-20 and we expect to start the transition to
cycle 4 targets in December.
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14. Meeting Announcements
The Riddle of Cooling Flows in Galaxies and Clusters of Galaxies (31 May - 4 June 2003 @ Charlottesville, VA, USA)
Recent observations, especially by XMM-Newton and Chandra, have
significantly broadened our view on cooling flows in galaxies and
clusters of galaxies. The wealth of new information through
observations has led to a flourishing development in theoretical
modelling. The purpose of this conference is to summarize relevant
observational results at all wavelengths, to compare the
predictions of models and simulations to these observations, and
to assess the impact of processes in cluster cores on the
application of galaxy clusters as cosmological probes.
Please visit the conference web page for further details
http://www.astro.virginia.edu/coolflow/.
Soft X-ray Emission From Clusters of Galaxies and
Related Phenomena (11-13, December 2002 @ Huntsville, AL, USA)
Exciting new data from XMM/Newton observations, along with an in-depth
analysis of ROSAT PSPC archives, have recently led to a wealth of new
information about the soft X-ray `excess' emission from clusters of
galaxies. Not only is the phenomenon spatially very extended, but the
details being revealed mean that we now have a realistic possibility of
solving the puzzle concerning the origin of the radiation. However the
correct interpretation may unfold, indications are that it will be one
of cosmological importance. The purpose of this meeting is to (a)
review the current observational status of the soft excess, identifying
priority issues to be settled in the next rounds of XMM and Chandra
opportunities (other timely missions such as Astro-E, may also be
addressed); (b) review the theoretical interpretations and how they are
constrained by the data; and (c) discuss the prospects of future
missions and the optimal payload designs to further our understanding
of this new radiation component and its place in cosmology. More
details of our first announcement may be found on "http://www.uah.edu/news/ClusterGalaxies.
Globular Clusters: Formation, Evolution and the Role of Compact Objects (27-31 January, 2003 @ ITP, UC-Santa Barbara, CA USA)
Our understanding of the formation and evolution of globular clusters
(GCs) is rapidly improving. Much recent progress on GC formation has
come from new observations of extragalactic GCs and, in particular,
from HST observations of cluster formation in starburst galaxies and in
interacting galaxies. Significant advances have also been realized in
numerical simulations of structure formation in the high-redshift
universe, which are now beginning to probe the relevant scales. In
spite of this tremendous recent progress, important questions remain
unresolved. These include whether the absence of dark matter halos
around GCs can be accommodated in any early formation model, why GCs do
not have a mass-radius relation when the clouds from which they form
almost certainly do, and how well our current models of their dynamical
evolution match the available data. This conference provides a forum
for discussing the latest contributions to this field. For further
information about the scientific aspects of the meeting and/or
presenting new results, please feel free to contact any of the
coordinators: L. Bildsten (bildsten@itp.ucsb.edu), A. Cool
(cool@stars.sfsu.edu), F. Rasio (rasio@northwestern.edu), or S. Zepf
(zepf@pa.msu.edu). For logistic details, please contact Susan Alemdar
(sue@itp.ucsb.edu). Registration can be filled out on the ITP web site
at http://www.itp.ucsb.edu/activities/conferences/.
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HEADNEWS, the electronic newsletter of the High Energy Astrophysics Division of the American Astronomical Society, is issued twice yearly by the HEAD Secretary-Treasurer. The HEAD Executive Committee Members are:
