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Author name code: stebbins
ADS astronomy entries on 2022-09-14
author:"Stebbins, Robin T."
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Title: Getting Ready for LISA: The Data, Support and Preparation
Needed to Maximize US Participation in Space-Based Gravitational
Wave Science
Authors: Holley-Bockelmann, Kelly; :; Bellovary, Jillian; Bender,
Peter; Berti, Emanuele; Brown, Warren; Caldwell, Robert; Cornish, Neil;
Darling, Jeremy; Digman, Matthew; Eracleous, Mike; Gultekin, Kayhan;
Haiman, Zoltan; Holley-Bockelmann, Kelly; Key, Joey; Larson, Shane;
Liu, Xin; McWilliams, Sean; Natarajan, Priyamvada; Shoemaker, David;
Shoemaker, Deirdre; Smith, Krista Lynne; Soares-Santos, Marcelle;
Robin; Stebbins
2020arXiv201202650H Altcode:
The NASA LISA Study Team was tasked to study how NASA might support US
scientists to participate and maximize the science return from the Laser
Interferometer Space Antenna (LISA) mission. LISA is gravitational wave
observatory led by ESA with NASA as a junior partner, and is scheduled
to launch in 2034. Among our findings: LISA science productivity
is greatly enhanced by a full-featured US science center and an open
access data model. As other major missions have demonstrated, a science
center acts as both a locus and an amplifier of research innovation,
data analysis, user support, user training and user interaction. In
its most basic function, a US Science Center could facilitate entry
into LISA science by hosting a Data Processing Center and a portal for
the US community to access LISA data products. However, an enhanced
LISA Science Center could: support one of the parallel independent
processing pipelines required for data product validation; stimulate
the high level of research on data analysis that LISA demands; support
users unfamiliar with a novel observatory; facilitate astrophysics
and fundamental research; provide an interface into the subtleties
of the instrument to validate extraordinary discoveries; train new
users; and expand the research community through guest investigator,
postdoc and student programs. Establishing a US LISA Science Center
well before launch can have a beneficial impact on the participation
of the broader astronomical community by providing training, hosting
topical workshops, disseminating mock catalogs, software pipelines,
and documentation. Past experience indicates that successful science
centers are established several years before launch; this early adoption
model may be especially relevant for a pioneering mission like LISA.
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Title: Space based gravitational wave astronomy beyond LISA
Authors: Mueller, Guido; Baker, John; Barke, Simon; Bender, Peter L.;
Berti, Emanuele; Caldwell, Robert; Conklin, John W.; Cornish, Neil;
Ferrara, Elizabeth C.; Holley-Bockelmann, Kelly; Kamai, Brittany;
Larson, Shane L.; Livas, Jeff; McWilliams, Sean T.; Mueller, Guido;
Natarajan, Priyamvada; Rioux, Norman; Sankar, Shannon S.; Schnittman,
Jeremy; Shoemaker, Deirdre; Slutsky, Jacob; Stebbins, Robin; Thorpe,
Ira; Ziemer, John
2019BAAS...51g.243M Altcode: 2019astro2020U.243M; 2019arXiv190711305B
This white paper surveys the science, technology and mission concepts
for a gravitational wave mission beyond LISA. The proposed small
scale activity is a technology development program that would support
a range of concepts and a mission concept study to choose a specific
mission concept for Astro2030.
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Title: Building a Field: The Future of Astronomy with Gravitational
Waves
Authors: Holley-Bockelmann, Kelly; Ziemer, John; Thorpe, Ira; Livas,
Jeff; Conklin, John W.; Caldwell, Robert; Berti, Emanuele; McWilliams,
Sean T.; Stebbins, Robin; Shoemaker, David; Ferrara, Elizabeth C.;
Larson, Shane L.; Shoemaker, Deirdre; Key, Joey Shapiro; Eracleous,
Michael; Schnittman, Jeremy; Baghi, Quentin; Kamai, Brittany; Mueller,
Guido; Bellovary, Jillian; Rioux, Norman; Baker, John; Cutler, Curt;
Natarajan, Priyamvada; Kelly, Bernard J.; Brandt, T. J.; Gabella,
William; Jani, Karan
2019BAAS...51g.228H Altcode: 2019arXiv191207642H; 2019astro2020U.228H
Harnessing the sheer discovery potential of GW Astronomy will require
bold, deliberate, and sustained efforts to train and develop the
requisite workforce. This basic infrastructure is needed as an enabling
foundation for research. We outline a set of recommendations to help
build a thriving, diverse, and inclusive new field.
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Title: The Laser Interferometer Space Antenna: Unveiling the
Millihertz Gravitational Wave Sky
Authors: Thorpe, James Ira; Ziemer, John; Thorpe, Ira; Livas, Jeff;
Conklin, John W.; Caldwell, Robert; Berti, Emanuele; McWilliams,
Sean T.; Stebbins, Robin; Shoemaker, David; Ferrara, Elizabeth C.;
Larson, Shane L.; Shoemaker, Deirdre; Key, Joey Shapiro; Vallisneri,
Michele; Eracleous, Michael; Schnittman, Jeremy; Kamai, Brittany;
Camp, Jordan; Mueller, Guido; Bellovary, Jillian; Rioux, Norman;
Baker, John; Bender, Peter L.; Cutler, Curt; Cornish, Neil; Hogan,
Craig; Manthripragada, Sridhar; Ware, Brent; Natarajan, Priyamvada;
Numata, Kenji; Sankar, Shannon R.; Kelly, Bernard J.; McKenzie, Kirk;
Slutsky, Jacob; Spero, Robert; Hewitson, Martin; Francis, Samuel;
DeRosa, Ryan; Yu, Anthony; Hornschemeier, Ann; Wass, Peter
2019BAAS...51g..77T Altcode: 2019arXiv190706482B; 2019astro2020U..77T
This whitepaper summarizes the status of the ESA-led Laser
Interferometer Space Antenna (LISA) mission and advocates for an
increased US role within the ‘medium’ mission category. The LISA
science case, mission concept, technical readiness, and organizational
partnerships are summarized and broad scenarios for US participation
are described.
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Title: NASA's Preparations for ESA's L3 Gravitational Wave Mission
Authors: Stebbins, Robin
2016APS..APRJ12003S Altcode:
The European Space Agency (ESA) selected gravitational-wave astrophysics
as the science theme for its third large mission opportunity, known as
`L3,' under its Cosmic Vision Programme. NASA is seeking a role as
an international partner in L3. NASA is: (1) participating in ESA's
early mission activities, (2) developing potential US technology
contributions, (3) participating in ESA's LISA Pathfinder mission,
(4) and conducting a study of how NASA might participate. This talk
will survey the status of these activities.
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Title: Mission and Instrument Design Trades for a Space-based
Gravitational Wave Observatory to Maximize Science Return
Authors: Livas, Jeffrey; Baker, John; Stebbins, Robin; Thorpe, James;
Larson, Shane; Sesana, Alberto
2016APS..APRJ12005L Altcode:
A space-based gravitational wave observatory is required to access
the rich array of astrophysical sources expected at frequencies
between 0.0001 and 0.1 Hz. The European Space Agency (ESA) chose
the Gravitational Universe as the science theme of its L3 launch
opportunity. A call for mission proposals will be released soon after
the completion of the LISA Pathfinder (LPF) mission. LPF is scheduled
to start science operations in March 2016, and finish by the end of
the year, so an optimized mission concept is needed now. There are
a number of possible design choices for both the instrument and the
mission. One of the goals for a good mission design is to maximize
the science return while minimizing risk and keeping costs low. This
presentation will review some of the main design choices for a LISA-like
laser interferometry mission and the impact of these choices on cost,
risk, and science return.
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Title: NASA's Preparations for ESA's L3 Gravitational Wave Mission
Authors: Stebbins, Robin T.
2016AAS...22740502S Altcode:
In November 2013, the European Space Agency (ESA) selected the science
theme, the "Gravitational Universe," for its third large mission
opportunity, known as 'L3,' under its Cosmic Vision Programme. The
planned launch date is 2034. NASA is seeking a role as an international
partner in L3. NASA is supporting: (1) US participation in early mission
studies, (2) US technology development, (3) pre-decadal preparations,
(4) ESA's LISA Pathfinder mission and (5) the ST7 Disturbance Reduction
System project. This talk summarizes NASA's preparations for a future
gravitational-wave mission.
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Title: Progress Toward a Space-Based Gravitational Wave Observatory
Authors: Livas, Jeffrey C.; Stebbins, Robin T.
2016IAUFM..29B.357L Altcode:
The discovery of binary pulsar PSR 1913+16 by Hulse & Taylor
in 1974 established the existence of gravitational waves, for
which the 1983 Nobel Prize was awarded. However, the measurement
of astrophysical parameters from gravitational waves will open an
entirely new spectrum for discovery and understanding of the Universe,
not simply a new window in the electromagnetic spectrum like gamma ray
telescopes in the 1970s. Two types of ground-based detectors, Advanced
LIGO/Virgo and Pulsar Timing Arrays, are expected to directly detect
gravitational waves in their respective frequency bands before the
end of the decade. However, many of the most exciting sources are in
the band from 0.1-100 mHz, accessible only from space due to seismic
and gravity gradient noise on Earth. The European Space Agency (ESA)
has chosen the 'Gravitational Universe' as the science theme for its
L3 Cosmic Visions opportunity, planned for launch in 2034. NASA is
planning to participate as a junior partner. Here we summarize progress
toward realizing a gravitational wave observatory in space.
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Title: Status of a Space-Based Gravitational-Wave Observatory at NASA
Authors: Stebbins, Robin
2015IAUGA..2257752S Altcode:
For over two decades, NASA has studied a flight project to build a
gravitational-wave observatory, and partnered with the European Space
Agency (ESA) to formulate and study such a mission. The spectacular
science and the well-defined and well-studied Laser Interferometer
Space Antenna (LISA) mission concept got high recommendations in
the U.S. astrophysics decadal surveys of 2000 and 2010.In 2013, ESA
selected the science theme, the “Gravitational Universe,” for the
third large mission opportunity, known as L3, under its Cosmic Vision
Programme. The planned launch date is 2034. ESA is considering a 20%
participation by an international partner, and NASA's Astrophysics
Division has begun negotiating a NASA role. The US research community
has studied the design consequences of a NASA contribution, evaluated
the science benefits and identified the technology requirements for
hardware that could be delivered by NASA.This talk will describe the
current state of: mission concept studies, US participation in an
ESA-led study, technology development, other relevant activities and
preparation for the 2020 decadal survey.
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Title: The Gravitational Universe - ESA's L3 mission
Authors: Mueller, Guido; Ando, Masaki; Binetruy, Pierre; Bouyer,
Philippe; Cacciapuoti, Luigi; Cruise, Mike; Favata, Fabio; Gehler,
Martin; Genzel, Reinhard; Jennrich, Oliver; Kasevich, Mark; Klipstein,
Bill; Perryman, Michael; Safa, Frederic; Schutz, Bernard; Stebbins,
Robin; Vitale, Stefano
2015APS..APR.U7001M Altcode:
Following the advice of ESA's Senior Survey Committee (SSC)
the Science Programme Committee (SPC) decided in November 2013 to
select the science theme “The Gravitational Universe” for their L3
mission. The Director of Science and Robotic Exploration (D/SRE) has
established a Gravitational Observatory Advisory Team (GOAT) to advise
on the scientific and technological approaches for a gravitational
wave observatory with a planned launch date in 2034. Our team is
comprised of scientists from Europe and the US as well as scientists
and engineers from ESA and observers from NASA and JAXA. We meet about
every ten weeks, evaluate the technical readiness of all necessary
technologies, study the science impact of different mission designs,
and will advise ESA on the required future technology development. We
will report on our progress and plans forward to a future space-based
gravitational-wave observatory. <P />For JAXA.
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Title: Architectures for a Space-based Gravitational-Wave Observatory
Authors: Stebbins, Robin
2015APS..APR.U7004S Altcode:
The European Space Agency (ESA) selected the science theme, the
“Gravitational Universe,” for the third large mission opportunity,
known as L3, under its Cosmic Vision Programme. The planned launch date
is 2034. ESA is considering a 20% participation by an international
partner, and NASA's Astrophysics Division has begun negotiating a NASA
role. We have studied the design consequences of a NASA contribution,
evaluated the science benefits and identified the technology
requirements for hardware that could be delivered by NASA. The
European community proposed a strawman mission concept, called eLISA,
having two measurement arms, derived from the well studied LISA (Laser
Interferometer Space Antenna) concept. The US community is promoting
a mission concept known as SGO Mid (Space-based Gravitational-wave
Observatory Mid-sized), a three arm LISA-like concept. If NASA were to
partner with ESA, the eLISA concept could be transformed to SGO Mid
by the addition of a third arm, thereby augmenting science, reducing
risk and reducing non-recurring engineering costs. The characteristics
of the mission concepts and the relative science performance of eLISA,
SGO Mid and LISA are described.
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Title: Future Gravitational-Wave Missions
Authors: Stebbins, Robin T.; NASA Gravitational-Wave Study Team
2015AAS...22533844S Altcode:
In November 2013, the European Space Agency (ESA) selected the science
theme, the 'Gravitational Universe,' for its third large mission
opportunity, known as L3, under its Cosmic Vision Programme. The
planned launch date is 2034. ESA is considering a 20% participation by
an international partner, and NASA's Astrophysics Division has indicated
an interest in participating. We have studied the design consequences of
a NASA contribution, evaluated the science benefits and identified the
technology requirements for hardware that could be delivered by NASA.The
European community proposed a strawman mission concept, called eLISA,
having two measurement arms, derived from the well studied LISA (Laser
Interferometer Space Antenna) concept. The US community is promoting
a mission concept known as SGO Mid (Space-based Gravitational-wave
Observatory Mid-sized), a three arm LISA-like concept. If NASA were
to partner with ESA, the eLISA concept could be transformed to SGO
Mid by the addition of a third arm, augmenting science, reducing risk
and reducing non-recurring engineering costs. The characteristics of
the mission concepts and the relative science performance of eLISA,
SGO Mid and LISA are described. Note that all results are based on
models, methods and assumptions used in NASA studies.
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Title: Gravitational-wave Missions at NASA
Authors: Stebbins, Robin; McNamara, Paul; Jennrich, Oliver
2014cosp...40E3193S Altcode:
In November 2013, ESA selected the science theme, the “Gravitational
Universe,” for its third large mission opportunity, known as L3, under
its Cosmic Visions Programme. The planned launch date is 2034. ESA is
considering a 20% participation by an international partner, and NASA's
Astrophysics Division has indicated an interest in participating. We
have studied the design consequences of a NASA contribution,
evaluated the science benefits and identified the technology
requirements for hardware that could be delivered by NASA. The
European community proposed a strawman mission concept, called eLISA,
having two measurement arms, derived from the well studied LISA (Laser
Interferometer Space Antenna) concept. The US community is promoting
a mission concept known as SGO Mid (Space-based Gravitational-wave
Observatory Mid-sized), a three arm LISA-like concept. If NASA were
to partner with ESA, the eLISA concept could be transformed to SGO
Mid by the addition of a third arm, augmenting science, reducing risk
and reducing non-recurring engineering costs. The characteristics of
the mission concepts and the relative science performance of eLISA,
SGO Mid and LISA are described.
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Title: eLISA: Astrophysics and cosmology in the millihertz regime
Authors: Amaro-Seoane, Pau; Aoudia, Sofiane; Babak, Stanislav;
Binétruy, Pierre; Berti, Emanuele; Bohé, Alejandro; Caprini,
Chiara; Colpi, Monica; Cornish, Neil J.; Danzmann, Karsten; Dufaux,
Jean-François; Gair, Jonathan; Hinder, Ian; Jennrich, Oliver;
Jetzer, Philippe; Klein, Antoine; Lang, Ryan N.; Lobo, Alberto;
Littenberg, Tyson; McWilliams, Sean T.; Nelemans, Gijs; Petiteau,
Antoine; Porter, Edward K.; Schutz, Bernard F.; Sesana, Alberto;
Stebbins, Robin; Sumner, Tim; Vallisneri, Michele; Vitale, Stefano;
Volonteri, Marta; Ward, Henry; Wardell, Barry
2013GWN.....6....4A Altcode: 2012arXiv1201.3621A
This document introduces the exciting and fundamentally new science and
astronomy that the European New Gravitational Wave Observatory (NGO)
mission (derived from the previous LISA proposal) will deliver. The
mission (which we will refer to by its informal name “eLISA”)
will survey for the first time the low-frequency gravitational wave
band (about 0:1 mHz to 1 Hz), with sufficient sensitivity to detect
interesting individual astrophysical sources out to z = 15. The
measurements described here will address the basic scientific goals
that have been captured in ESA's “New Gravitational Wave Observatory
Science Requirements Document”; they are presented here so that the
wider scientific community can have access to them. The eLISA mission
will discover and study a variety of cosmic events and systems with
high sensitivity: coalescences of massive black holes binaries, brought
together by galaxy mergers; mergers of earlier, less-massive black
holes during the epoch of hierarchical galaxy and black-hole growth;
stellar-mass black holes and compact stars in orbits just skimming the
horizons of massive black holes in galactic nuclei of the present era;
extremely compact white dwarf binaries in our Galaxy, a rich source of
information about binary evolution and about future Type Ia supernovae;
and possibly most interesting of all, the uncertain and unpredicted
sources, for example relics of inflation and of the symmetry-breaking
epoch directly after the Big Bang. eLISA's measurements will allow
detailed studies of these signals with high signal-to-noise ratio,
addressing most of the key scientific questions raised by ESA's Cosmic
Vision programme in the areas of astrophysics and cosmology. They will
also provide stringent tests of general relativity in the strong-field
dynamical regime, which cannot be probed in any other way. This document
not only describes the science but also gives an overview on the mission
design and orbits. LISA's heritage in the eLISA design will be clear to
those familiar with the previous proposal, as will its incorporation of
key elements of hardware from the LISA Pathfinder mission, scheduled
for launch by ESA in 2014. But eLISA is fundamentally a new mission,
one that will pioneer the completely new science of low-frequency
gravitational wave astronomy.
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Title: The Gravitational Universe
Authors: eLISA Consortium; Amaro Seoane, P.; Aoudia, S.; Audley, H.;
Auger, G.; Babak, S.; Baker, J.; Barausse, E.; Barke, S.; Bassan, M.;
Beckmann, V.; Benacquista, M.; Bender, P. L.; Berti, E.; Binétruy, P.;
Bogenstahl, J.; Bonvin, C.; Bortoluzzi, D.; Brause, N. C.; Brossard,
J.; Buchman, S.; Bykov, I.; Camp, J.; Caprini, C.; Cavalleri, A.;
Cerdonio, M.; Ciani, G.; Colpi, M.; Congedo, G.; Conklin, J.; Cornish,
N.; Danzmann, K.; de Vine, G.; DeBra, D.; Dewi Freitag, M.; Di Fiore,
L.; Diaz Aguilo, M.; Diepholz, I.; Dolesi, R.; Dotti, M.; Fernández
Barranco, G.; Ferraioli, L.; Ferroni, V.; Finetti, N.; Fitzsimons,
E.; Gair, J.; Galeazzi, F.; Garcia, A.; Gerberding, O.; Gesa, L.;
Giardini, D.; Gibert, F.; Grimani, C.; Groot, P.; Guzman Cervantes, F.;
Haiman, Z.; Halloin, H.; Heinzel, G.; Hewitson, M.; Hogan, C.; Holz,
D.; Hornstrup, A.; Hoyland, D.; Hoyle, C. D.; Hueller, M.; Hughes,
S.; Jetzer, P.; Kalogera, V.; Karnesis, N.; Kilic, M.; Killow, C.;
Klipstein, W.; Kochkina, E.; Korsakova, N.; Krolak, A.; Larson, S.;
Lieser, M.; Littenberg, T.; Livas, J.; Lloro, I.; Mance, D.; Madau, P.;
Maghami, P.; Mahrdt, C.; Marsh, T.; Mateos, I.; Mayer, L.; McClelland,
D.; McKenzie, K.; McWilliams, S.; Merkowitz, S.; Miller, C.; Mitryk,
S.; Moerschell, J.; Mohanty, S.; Monsky, A.; Mueller, G.; Müller,
V.; Nelemans, G.; Nicolodi, D.; Nissanke, S.; Nofrarias, M.; Numata,
K.; Ohme, F.; Otto, M.; Perreur-Lloyd, M.; Petiteau, A.; Phinney,
E. S.; Plagnol, E.; Pollack, S.; Porter, E.; Prat, P.; Preston, A.;
Prince, T.; Reiche, J.; Richstone, D.; Robertson, D.; Rossi, E. M.;
Rosswog, S.; Rubbo, L.; Ruiter, A.; Sanjuan, J.; Sathyaprakash, B. S.;
Schlamminger, S.; Schutz, B.; Schütze, D.; Sesana, A.; Shaddock,
D.; Shah, S.; Sheard, B.; Sopuerta, C. F.; Spector, A.; Spero, R.;
Stanga, R.; Stebbins, R.; Stede, G.; Steier, F.; Sumner, T.; Sun,
K. -X.; Sutton, A.; Tanaka, T.; Tanner, D.; Thorpe, I.; Tröbs, M.;
Tinto, M.; Tu, H. -B.; Vallisneri, M.; Vetrugno, D.; Vitale, S.;
Volonteri, M.; Wand, V.; Wang, Y.; Wanner, G.; Ward, H.; Ware, B.;
Wass, P.; Weber, W. J.; Yu, Y.; Yunes, N.; Zweifel, P.
2013arXiv1305.5720E Altcode: 2013arXiv1305.5720C; 2013arXiv1305.5720D
The last century has seen enormous progress in our understanding of the
Universe. We know the life cycles of stars, the structure of galaxies,
the remnants of the big bang, and have a general understanding of how
the Universe evolved. We have come remarkably far using electromagnetic
radiation as our tool for observing the Universe. However, gravity is
the engine behind many of the processes in the Universe, and much of
its action is dark. Opening a gravitational window on the Universe will
let us go further than any alternative. Gravity has its own messenger:
Gravitational waves, ripples in the fabric of spacetime. They travel
essentially undisturbed and let us peer deep into the formation of
the first seed black holes, exploring redshifts as large as z ~ 20,
prior to the epoch of cosmic re-ionisation. Exquisite and unprecedented
measurements of black hole masses and spins will make it possible to
trace the history of black holes across all stages of galaxy evolution,
and at the same time constrain any deviation from the Kerr metric of
General Relativity. eLISA will be the first ever mission to study the
entire Universe with gravitational waves. eLISA is an all-sky monitor
and will offer a wide view of a dynamic cosmos using gravitational waves
as new and unique messengers to unveil The Gravitational Universe. It
provides the closest ever view of the early processes at TeV energies,
has guaranteed sources in the form of verification binaries in the Milky
Way, and can probe the entire Universe, from its smallest scales around
singularities and black holes, all the way to cosmological dimensions.
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Title: A Possible U.S. Contribution to eLISA, a Gravitational-Wave
Mission Concept for ESA’s L2 Opportunity
Authors: Stebbins, Robin T.
2013HEAD...1312104S Altcode:
Scientists from the member states of the European Space Agency
(ESA) that proposed the New Gravitational Wave Observatory (NGO) have
organized the eLISA Consortium to propose for ESA's next large mission
opportunity, called L2. The Evolved Laser Interferometer Space Antenna
(eLISA) concept is derived from the well studied LISA concept for a
space-based, gravitational-wave mission. eLISA will use the technology
being developed in the LISA Pathfinder mission in a two-arm version that
achieves much of the LISA science endorsed by the Decadal Survey. If
invited, NASA could join the project as a junior partner with a ~15%
share. This could enable a third arm and substantially augment the
science return. While the details of the eLISA concept to be proposed
have not yet been finalized, the SGO Mid concept, recently studied
in the U.S., constitutes a possible augmented concept for an ESA/NASA
partnership. The eLISA concept and the SGO Mid concept are described
and compared.
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Title: Status of eLISA
Authors: Stebbins, Robin T.; Jennrich, O.; Consortium, eLISA
2013AAS...22115305S Altcode:
Scientists from the member states of the European Space Agency
(ESA) that proposed the New Gravitational Wave Observatory (NGO)
are organizing the eLISA Consortium to propose for the next large
mission opportunity. The Evolved Laser Interferometer Space Antenna
(eLISA) concept is derived from the well studied LISA concept for a
space-based, gravitational-wave mission. eLISA will use the technology
being developed in the LISA Pathfinder mission in a two-arm version that
achieves much of the science of LISA. eLISA will: (1) survey very many
compact stellar-mass binaries and study the structure of the Milky Way;
(2) discover black holes formed at early epochs that grew over cosmic
time to generate the supermassive black holes present in most galactic
nuclei today; (3) trace the interaction of galaxy growth and massive
black hole growth over the entire history of galaxy formation; (4)
explore the populations of stellar-mass compact objects in galactic
nuclei and their dynamics; (5) observe highly relativistic coalescences
of black hole binaries, and provide exceptionally strong tests of
the predictions of General Relativity; and (6) probe new physics and
cosmology with gravitational waves, and search for unforeseen sources
of gravitational waves. The key parameters of the design concept and a
quantitative assessment of the science performance are given. NASA and
the U.S. research community may be able to participate, and possibly
extend the capabilities of the mission.
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Title: NASA's Gravitational-Wave Mission Concept Study
Authors: Stebbins, Robin; Jennrich, Oliver; McNamara, Paul
2012cosp...39.1890S Altcode: 2012cosp.meet.1890S
With the conclusion of the NASA/ESA partnership on the Laser
interferometer Space Antenna (LISA) Project, NASA initiated a study to
explore mission concepts that will accomplish some or all of the LISA
science objectives at lower cost. The Gravitational-Wave Mission Concept
Study consisted of a public Request for Information (RFI), a Core Team
of NASA engineers and scientists, a Community Science Team, a Science
Task Force, and an open workshop. The RFI yielded were 12 mission
concepts, 3 instrument concepts and 2 technologies. The responses
ranged from concepts that eliminated the drag-free test mass of LISA to
concepts that replace the test mass with an atom interferometer. The
Core Team reviewed the noise budgets and sensitivity curves, the
payload and spacecraft designs and requirements, orbits and trajectories
and technical readiness and risk. The Science Task Force assessed the
science performance by calculating the horizons, the detection rates and
the accuracy of astrophysical parameter estimation for massive black
hole mergers, stellar-mass compact objects inspiraling into central
engines, and close compact binary systems. Three mission concepts have
been studied by Team-X, JPL's concurrent design facility, to define
a conceptual design, evaluate key performance parameters, assess risk
and estimate cost and schedule. The Study results are summarized.
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Title: Low-frequency gravitational-wave science with eLISA/NGO
Authors: Amaro-Seoane, Pau; Aoudia, Sofiane; Babak, Stanislav;
Binétruy, Pierre; Berti, Emanuele; Bohé, Alejandro; Caprini,
Chiara; Colpi, Monica; Cornish, Neil J.; Danzmann, Karsten; Dufaux,
Jean-François; Gair, Jonathan; Jennrich, Oliver; Jetzer, Philippe;
Klein, Antoine; Lang, Ryan N.; Lobo, Alberto; Littenberg, Tyson;
McWilliams, Sean T.; Nelemans, Gijs; Petiteau, Antoine; Porter, Edward
K.; Schutz, Bernard F.; Sesana, Alberto; Stebbins, Robin; Sumner, Tim;
Vallisneri, Michele; Vitale, Stefano; Volonteri, Marta; Ward, Henry
2012CQGra..29l4016A Altcode: 2012arXiv1202.0839A
We review the expected science performance of the New Gravitational-Wave
Observatory (NGO, a.k.a. eLISA), a mission under study by the European
Space Agency for launch in the early 2020s. eLISA will survey the
low-frequency gravitational-wave sky (from 0.1 mHz to 1 Hz), detecting
and characterizing a broad variety of systems and events throughout
the Universe, including the coalescences of massive black holes brought
together by galaxy mergers; the inspirals of stellar-mass black holes
and compact stars into central galactic black holes; several millions
of ultra-compact binaries, both detached and mass transferring,
in the Galaxy; and possibly unforeseen sources such as the relic
gravitational-wave radiation from the early Universe. eLISA’s high
signal-to-noise measurements will provide new insight into the structure
and history of the Universe, and they will test general relativity in
its strong-field dynamical regime.
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Title: Plans For A Next Generation Space-based Gravitational-wave
Observatory (NGO)
Authors: Livas, Jeffrey C.; Stebbins, R. T.; Jennrich, O.; NGO Mission
Development Team
2012AAS...21914626L Altcode:
The European Space Agency (ESA) is currently in the process of selecting
a mission for the Cosmic Visions Program. A space-based gravitational
wave observatory in the low-frequency band (0.0001 - 1 Hz) of the
gravitational wave spectrum is one of the leading contenders. This
low frequency band has a rich spectrum of astrophysical sources, and
the LISA concept has been the key mission to cover this science for
over twenty years. Tight budgets have recently forced ESA to consider
a reformulation of the LISA mission concept that will allow the Cosmic
Visions Program to proceed on schedule either with the US as a minority
participant, or independently of the US altogether. We report on the
status of these reformulation efforts.
---------------------------------------------------------
Title: Concepts For A Space-based Gravitational-wave Observatory (SGO)
Authors: Stebbins, Robin T.; Gravitational Wave Concept Definition Team
2012AAS...21914624S Altcode:
The low-frequency band (0.0001 - 1 Hz) of the gravitational wave
spectrum has the most interesting astrophysical sources. It is only
accessible from space. The Laser Interferometer Space Antenna (LISA)
concept has been the leading contender for a space-based detector in
this band. Despite a strong recommendation from Astro2010, constrained
budgets motivate the search for a less expensive concept, even at the
loss of some science. We have explored the range of lower-cost mission
concepts derived from two decades of studying the LISA concept. We
describe LISA-like concepts that span the range of affordable and
scientifically worthwhile missions, and summarize the analyses behind
them.
---------------------------------------------------------
Title: New Concepts for Space-Based Gravitational Wave Missions
Authors: Stebbins, Robin T.; Baker, J. G.; Cooley, D.; Gallagher,
R. J.; Hughes, S. P.; Livas, J. C.; Simpson, J. E.; Thorpe, J. I.;
Welter, G. L.
2011HEAD...12.0902S Altcode:
The most interesting astrophysical sources in the gravitational wave
spectrum lie in the low-frequency band (0.0001 - 1 Hz), which is only
accessible from space. For two decades, the LISA concept has been
the leading contender for a detector in this band. Despite a strong
recommendation from Astro2010, there is strong motivation to find a less
expensive concept, even at the loss of some science. We are searching
for a lower cost mission concept by examining alternate orbits,
less-capable measurement concepts, radically different implementations
of the measurement concept and other cost-saving ideas. We report the
results of our searches to date, and summarize the analyses behind them.
---------------------------------------------------------
Title: Characterization of photoreceivers for LISA
Authors: Guzmán Cervantes, F.; Livas, J.; Silverberg, R.; Buchanan,
E.; Stebbins, R.
2011CQGra..28i4010G Altcode: 2012arXiv1203.2862G
LISA will use quadrant photoreceivers as front-end devices for the
phasemeter measuring the motion of drag-free test masses in both angular
orientation and separation. We have set up a laboratory testbed for the
characterization of photoreceivers. Some of the limiting noise sources
have been identified and their contribution has been either measured
or derived from the measured data. We have built a photoreceiver with
a 0.5 mm diameter quadrant photodiode with an equivalent input current
noise of better than 1.8 pA Hz<SUP>-1/2</SUP> below 20 MHz and a 3 dB
bandwidth of 34 MHz.
---------------------------------------------------------
Title: Preliminary Investigations of an Optical Assembly Tracking
Mechansim for LISA
Authors: Ira Thorpe, James; Stebbins, Robin
2010cosp...38.3793I Altcode: 2010cosp.meet.3793I
After injection into their specific orbits, the position of the
LISA spacecraft are not actively controlled. Rather the spacecraft
are allowed to passively follow their trajectories and the roughly
equilateral triangular constellation is preserved. Slight variations
in the orbits cause the constellation to experience both periodic and
secular variations, one consequence of which is a variation in the
interior angles of the constellation on the order of one degree. This
variation is larger than the field of view of the LISA telescope,
requiring a mechanism for each spacecraft to maintain pointing to its
two companions. This Optical Assembly Tracking Mechanism (OATM) will
be used to accommodate these variations while maintaining pointing at
the ten nanoradian level to the far spacecraft. Here we report on a
possible design for the OATM as well as initial results from a test
campaign of a piezo-inchworm actuator used to drive the mechanism.
---------------------------------------------------------
Title: LISA Technology Development, Risk Reduction and Mission
Formulation at NASA
Authors: Stebbins, Robin; Ziemer, John; Livas, Jeffrey; Ira Thorpe,
James; Merkowitz, Stephen
2010cosp...38.3757S Altcode: 2010cosp.meet.3757S
The Laser Interferometer Space Antenna (LISA) is a joint ESA-NASA
project to design, build and operate a space-based gravitational wave
detector based on a laser interferometer. LISA relies on several
technologies that are either new to spaceflight or must perform at
levels not previously demonstrated in a spaceflight environment. The
ESA-led LISA Pathfinder mission is the main effort to demonstrate LISA
technology. NASA also supports complementary ground-based technology
development and risk reduction activities. This presentation will
report the status of NASA work on micronewton thrusters, the telescope,
the optical pointing subsystem and mission formulation. More details
on some of these topics will be given in posters. Other talks and
posters will describe NASA-supported work on the laser subsystem, the
phasemeter, and aspects of the interferometry. Two flight-qualified
clusters of four colloid micronewton thrusters, each capable of thrust
levels between 5 and 30 µN with a resolution ¡0.1 µN and a thrust
noise ¡0.1 µN/sqrtHz (0.001 to 4 Hz), have been integrated onto the
LISA Pathfinder spacecraft. The complementary ground-based development
focuses on lifetime demonstration. Laboratory verification of failure
models and accelerated life tests are just getting started. LISA
needs a 40 cm diameter, afocal telescope for beam expansion/reduction
that maintains an optical pathlength stability of 1 pm/sqrtHz in
an extremely stable thermal environment. A mechanical prototype of
a silicon carbide primary-secondary structure has been fabricated
for stability testing. Two optical assemblies must point at different
distant spacecraft with nanoradian accuracy over 1° annual variation in
the angle between the distant spacecraft. A candidate piezo-inchworm
actuator is being tested in a suitable testbed. In addition to
technology development, NASA has carried out several studies in support
of the mission formulation. The results of systems engineering work
on flight software, avionics and reliability will be summarized.
---------------------------------------------------------
Title: Instrumentation and Technology for the Laser Interferometer
Space Antenna (LISA)
Authors: Prince, Thomas Allen; Jennrich, O.; Klipstein, W.; Livas,
J.; McNamara, P.; Merkowitz, S.; Sallusti, M.; Stebbins, R.
2010AAS...21548210P Altcode: 2010BAAS...42..575P
This poster discusses the present status of the technology and
instrumentation for the joint ESA/NASA gravitational wave detector,
LISA, focusing on&nbspa description of the main payload items, such
as: (1) the interferometric measurement system, comprising the optical
system, which includes the optical bench and the telescope, the laser
system, and the phase measurement system; and, (2) the disturbance
reduction system, including the gravitational reference sensor, the
charge control system, and the micro-propulsion&nbspsystem.
---------------------------------------------------------
Title: Preliminary LISA telescope spacer design
Authors: Livas, Jeffrey; Stebbins, Robin; Arsenovic, Petar;
Castellucci, Kevin; Generie, Joseph; Howard, Joseph; Mueller, Guido;
Preston, Alix; Sanjuan, Josep; Williams, Luke
2010cosp...38.3783L Altcode: 2010cosp.meet.3783L
The LISA mission observes gravitational waves by measuring the
separations between freely floating proof masses located 5 million
kilometers apart with an accuracy of 10 picometers. The separations are
measured interferometrically. The telescope is an afocal Cassegrain
style design with a magnification of 80x. The entrance pupil has
a 40 cm diameter and will either be centered on-axis or de-centered
off-axis to avoid obscurations. Its two main purposes are to transform
the small diameter beam used on the optical bench to a diffraction
limited collimated beam to efficiently transfer the metrology laser
between spacecraft, and to receive the incoming light from the far
spacecraft. It transmits and receives simultaneously. The basic optical
design and requirements are well understood for a conventional telescope
design for imaging applications, but the LISA design is complicated
by the additional requirement that the total optical path through the
telescope must remain stable at the picometer level over the measurement
band during the mission to meet the measurement accuracy. This poster
describes the requirements for the telescope and the preliminary
work that has been done to understand the materials and mechanical
issues associated with the design of a passive metering structure to
support the telescope and to maintain the spacing between the primary
and secondary mirrors in the LISA on-orbit environment. This includes
the requirements flowdown from the science goals, thermal modeling of
the spacecraft and telescope to determine the expected temperature
distribution, layout options for the telescope including an on-and
off-axis design, and plans for fabrication and testing.
---------------------------------------------------------
Title: The LISA Pathfinder Mission
Authors: Stebbins, Robin T.; LISA Pathfinder Science Working Team
2010AAS...21548214S Altcode: 2010BAAS...42..575S
LISA Pathfinder (formerly known as SMART-2) is a European Space Agency
(ESA) mission designed to pave the way for the joint ESA/NASA Laser
Interferometer Space Antenna (LISA) mission by testing in flight the
critical technologies required for space-borne gravitational wave
detection: it will put two test masses in a near-perfect gravitational
free-fall and control and measure their motion with unprecedented
accuracy. <P />LISA Pathfinder is currently in the integration and
test phase of the development, and is due to be launched on a dedicated
launch vehicle in late 2011, with first results on the performance of
the system being available approximately 6 months later. <P />This
poster will describe the mission in detail, give the current status
of the spacecraft development, and highlight the future milestones in
the integration and test campaign.
---------------------------------------------------------
Title: LISA telescope spacer design investigations
Authors: Sanjuan, Josep; Mueller, Guido; Livas, Jeffrey; Preston,
Alix; Arsenovic, Petar; Castellucci, Kevin; Generie, Joseph; Howard,
Joseph; Stebbins, Robin
2010cosp...38.3791S Altcode: 2010cosp.meet.3791S
The Laser Interferometer Space Antenna (LISA) is a space-based
gravitational wave observa-tory with the goal of observing Gravitational
Waves (GWs) from astronomical sources in a frequency range from 30
µHz to 0.1 Hz. The detection of GWs at such low frequency requires
measurements of distances at the pico-meter level between bodies
separated by 5 million kilo-meters. The LISA mission consists of
three identical spacecraft (SC) separated by 5 × 106 km forming an
equilateral triangle. Each SC contains two optical assemblies and
two vacuum en-closures housing one proof mass (PM) in geodesic (free
fall) motion each. The two assemblies on one SC are each pointing
towards an identical assembly on each of the other two SC to form
a non-equal arm interferometer. The measurement of the GW strain is
done by measuring the change in the length of the optical path between
the PMs of one arm relative to the other arms caused by the pass of a
GW. An important element of the Interferometric Measurement System (IMS)
is the telescope which, on one hand, gathers the light coming from the
far SC (∼100 pW) and, on the other hand, expands and collimates the
small outgoing beam ( 1 W) and sends it to the far SC. Due to the very
demanding sensitivity requirements care must be taken in the design and
validation of the telescope not to degrade the IMS performance. For
instance, the diameter of the telescope sets the the shot noise of
the IMS and depends critically on the diameter of the primary and the
divergence angle of the outgoing beam. As the telescope is rather fast
telescope, the divergence angle is a critical function of the overall
separation between the primary and secondary. Any long term changes of
the distance of more than a a few micro-meter would be detrimental
to the LISA mission. Similarly challenging are the requirements
on the in-band path-length noise for the telescope which has to be
kept below 1 pm Hz-1/2 in the LISA band. Different configurations
(on-axis/off axis) and materials such as Silicon Carbide (SiC) and
Carbon Fiber Reinforced Plastic (CFRP) are considered to be used in the
telescope spacer structure. We will describe our experimental efforts
to understand and quantify the behavior of different materials and
also discuss a first investigation of a specific on-axis SiC telescope
spacer for LISA. This work is supported by NASA contract 00069955.
---------------------------------------------------------
Title: Rightsizing LISA
Authors: Stebbins, R. T.
2009CQGra..26i4014S Altcode: 2009arXiv0904.1029S
The Laser Interferometer Space Antenna (LISA) science requirements
and conceptual design have been fairly stable for over a decade. In
the interest of reducing costs, the LISA Project at NASA has looked
for simplifications of the architecture, at downsizing of subsystems
and at descopes of the entire mission. This is a natural activity
of the formulation phase and one that is particularly timely in
the current NASA budgetary context. There is, and will continue to
be, enormous pressure for cost reduction from both ESA and NASA,
reviewers and the broader research community. Here, the rationale
for the baseline architecture is reviewed, and recent efforts to find
simplifications and other reductions that might lead to savings are
reported. A few possible simplifications have been found in the LISA
baseline architecture. In the interest of exploring cost sensitivity,
one moderate and one aggressive descope have been evaluated; the cost
savings are modest and the loss of science is not.
---------------------------------------------------------
Title: LISA Pathfinder
Authors: Stebbins, Robin T.; McNamara, P. W.
2009AAS...21344906S Altcode: 2009BAAS...41Q.341S
LISA Pathfinder, formerly known as SMART-2, is the second of the
European Space Agency's Small Missions for Advanced Research and
Technology. The mission will pave the way for the joint ESA/NASA Laser
Interferometer Space Antenna (LISA), by testing the core assumption
of gravitational wave detection - and to a larger extent, General
Relativity - that free particles follow geodesics. <P />In order to meet
the goals of the mission, and to prepare the way for LISA, several new
technologies must be demonstrated in a space environment. These include:
inertial sensors, high-precision laser metrology, drag-free control and
micro-Newton proportional thrusters. <P />LISA Pathfinder will carry
two payloads: the LISA Technology Package (LTP), provided by European
Member States and ESA, and the Disturbance Reduction System (DRS)
provided by NASA. The DRS has passed its pre-ship acceptance review
and has been delivered to ESA, while the LTP has passed its Critical
Design Review, with flight hardware currently being manufactured and
tested. <P />The spacecraft development is also proceeding well; the
flight structures of both the science module and propulsion module
are undergoing environmental testing, while subsystem flight hardware
is being delivered to the spacecraft testbeds. <P />LISA Pathfinder
will be launched on a dedicated launch vehicle in late 2010. After
15 apogee raising manoeuvres, the sciencecraft will enter its final
orbit around the first Sun-Earth Lagrange point. First science results
are expected approximately three months after launch. <P />Here we
will give an overview of the mission including the technologies being
demonstrated. We will also report on the status of the flight hardware
testing, and on the status of the ground system.
---------------------------------------------------------
Title: Recent progress at NASA in LISA formulation and technology
development
Authors: Stebbins, R. T.
2008CQGra..25k4050S Altcode:
Over the last year, the NASA half of the joint LISA project has
focused its efforts on responding to a major review, and advancing
the formulation and technology development of the mission. The
NAS/NRC Beyond Einstein program assessment review will be described,
including the outcome. The basis of the LISA science requirements
has changed from detection determined by integrated signal-to-noise
ratio to observation determined by uncertainty in the estimation of
astrophysical source parameters. The NASA team has further defined the
spacecraft bus design, participated in many design trade studies and
advanced the requirements flow down and the associated current best
estimates of performance. Recent progress in technology development
is also summarized.
---------------------------------------------------------
Title: Astrophysics At z 10 With Gravitational Waves
Authors: Stebbins, Robin T.
2008HEAD...10.0602S Altcode:
What astrophysics can be done at redshifts beyond 5 using gravitational
waves? Historically, gravitational wave antennas have been characterized
by their detection capability. This is measured in terms of signal-noise
ratio, and implies a rate of false positives and false negatives. But
to do useful astrophysics, one would like to measure - or more
properly, estimate - astrophysical parameters of the gravitational wave
sources. In the interest of strengthening the connection between science
objectives and a specific instrument performance, the LISA community
has reformulated the LISA science requirements around the anticipated
uncertainty in astrophysical parameter estimation. The rationale for
this characterization of LISA and a summary of the astrophysics that
LISA can do will be given.
---------------------------------------------------------
Title: LISA Technology Development at GSFC
Authors: Thorpe, James Ira; Livas, Jeffrey; Stebbins, Robin
2008cosp...37.3184T Altcode: 2008cosp.meet.3184T
The prime focus of LISA technology development efforts at NASA/GSFC
has been in LISA interferometry, specifically in the area of laser
frequency noise mitigation. Laser frequency noise is addressed through
a combination of stabilization and common-mode rejection. Current
plans call for two stages of stabilization, pre-stabilization to
a local frequency reference and further stabilization using the
constellation as a frequency reference. In order for these techniques
to be used simultaneously, the pre-stabilization step must provide an
adjustable frequency offset. Here we report on a modification to the
standard modulation/demodulation technique used to stabilize to optical
cavities that generates a frequency-tunable reference from a fixedlength
cavity. This technique requires no modifications to the cavity itself
and only minor modifications to the components. The measured noise
performance and dynamic range of the laboratory prototype meet the
LISA requirements.
---------------------------------------------------------
Title: Science requirements for LISA
Authors: Stebbins, Robin
2008cosp...37.3029S Altcode: 2008cosp.meet.3029S
Historically, gravitational wave antennas have been characterized by
their detection capability. This is measured in terms of signal-to-noise
ratio, and implies a rate of false positives and false negatives. But
to do useful astrophysics, one would like to measure - or more
properly, estimate - astrophysical parameters of the gravitational wave
sources. In the interest of strengthening the connection between science
objectives and a specific instrument performance, the LISA community
has reformulated the LISA science requirements around the anticipated
uncertainty in astrophysical parameter estimation. The rationale for
this characterization of LISA and a summary of the astrophysics and
fundamental physics that LISA can do will be given. LISA will be able
to make precision measurements of sources out to z∼10.
---------------------------------------------------------
Title: The LISA Pathfinder Mission
Authors: Stebbins, Robin T.; LISA Pathfinder Science Team
2007AAS...21114009S Altcode: 2007BAAS...39..990S
LISA Pathfinder is an ESA mission designed to pave the way for the
joint ESA/NASA Laser Interferometer Space Antenna (LISA) mission by
testing in flight the critical technologies required for space-borne
gravitational wave detection. It will put two test masses in a
near-perfect gravitational free-fall and measure their motion with
unprecedented accuracy. <P />LISA Pathfinder will carry two technology
payloads, the European provided LISA Technology Package (LTP), and
the NASA provided Disturbance Reduction System (DRS), also known as
the ST-7 mission of the New Millennium Program. The LTP comprises
two inertial sensors, high precision laser metrology, drag-free
control and an ultra-precise micro-Newton propulsion system. The DRS
consists of a drag-free control system and a micro-Newton propulsion
system. The DRS will use the LTP inertial sensors, each of which has a
proof mass, reference housing with electrodes for capacitive sensing
and actuation and discharging systems. <P />LISA Pathfinder is due
to be launched in the first half of 2010, with first results on the
performance of the system being available approx 6 months later. <P
/>This poster summarizes the mission concept and reports the progress
in the last year, and the current status as the mission nears final
integration. Many spacecraft subsystems have been delivered. Detailed
planning for the orbital test sequences and development of the data
reduction software has advanced significantly. Ground support equipment
and test procedures for the spacecraft and payloads is also well
along. Details of the LISA technology to be flight tested will be given.
---------------------------------------------------------
Title: The LISA Pathfinder Mission
Authors: Stebbins, Robin T.; LISA Pathfinder Science Team
2006AAS...209.7403S Altcode: 2006BAAS...38..990S
LISA Pathfinder (formerly known as SMART-2) is an ESA mission designed
to pave the way for the joint ESA/NASA Laser Interferometer Space
Antenna (LISA) mission by testing in flight the critical technologies
required for space-borne gravitational wave detection: it will put two
test masses in a near-perfect gravitational free-fall and control and
measure their motion with unprecedented accuracy. <P />LISA Pathfinder
will carry two technology payloads, the European provided LISA
Technology Package (LTP), and the NASA provided Disturbance Reduction
System (DRS). The LTP comprises two inertial sensors, high precision
laser metrology, drag-free control and an ultra-precise micro-Newton
propulsion system. The DRS consists of a drag-free control system and
a micro-Newton propulsion system. The DRS will use the LTP inertial
sensors. <P />LISA Pathfinder is due to be launched in late 2009,
with first results on the performance of the system being available
approx 6 months later. <P />This poster gives an introduction to, and
status of, the mission, followed by more details on the technologies
to be tested in a space environment. It will also highlight the ways
in which the LISA Pathfinder mission will be used for the preparation
of LISA, e.g. ground segment development, on-orbit commissioning of
the hardware, etc. as well as technology development.
---------------------------------------------------------
Title: LISA Mission Architecture
Authors: Jedrich, Nicholas M.; Stebbins, R. T.; Livas, J. C.;
Merkowitz, S. M.; Mink, R. G.
2006AAS...209.7402J Altcode: 2006BAAS...38..990J
The Laser Interferometer Space Antenna (LISA) mission is unique
from a mission design perspective in that three spacecraft and their
associated operations form one distributed science instrument, unlike
more conventional missions where an instrument(s) is a component of
an individual spacecraft. The interferometer measurements between
spacecraft that form the basis for the science measurements,
i.e. strain, relies on all three of the spacecraft interacting as
designed. The performance of one spacecraft in the LISA constellation
is directly coupled to the performance of the two remaining spacecraft
in order for the instrument to collect meaningful science data. This
dependency on all three spacecraft to function as the instrument is the
primary driver for unique design requirements that span all spacecraft
subsystems and the overall mission design. A detailed discussion
will be presented that describes the spacecraft and current mission
architecture needed to meet the LISA science requirements.
---------------------------------------------------------
Title: System Validation and Verification Testing for the Laser
Interferometry Space Antenna (LISA)
Authors: Livas, Jeffrey C.; Jedrich, N.; Merkowitz, S. M.; Stebbins,
R. T.
2006AAS...209.7404L Altcode: 2006BAAS...38..990L
The Laser Interferometry Space Antenna (LISA) mission is a set of 3
spacecraft that fly in a heliocentric orbit in an equilateral triangle
formation to detect gravitational waves. Each side of the triangle
is 5 million km long, and the formation detects passing waves by
closely monitoring the distance between spacecraft. <P />The ideal for
system-level testing of instruments and spacecraft is to “test as you
fly”. Given that the inter-spacecraft distance is approximately 13
times the distance between the earth and the moon, Ground testing for
the LISA instrument will not be able to meet this ideal in a number
of areas, so a combination of testing, simulation, and analysis will
be needed instead. This paper will outline some of the areas where
direct testing on the ground will not be possible, and discuss some
of ideas, concepts and methods to meet that challenge. <P />The focus
of the discussion will be on the optical and system-level aspects of
the testing, as many of the issues associated with the proof masses
and drag-free spacecraft are covered by the LISA Pathfinder mission.
---------------------------------------------------------
Title: LISA Mission Tutorial
Authors: Stebbins, Robin
2006AIPC..873....3S Altcode:
The Laser Interferometer Space Antenna (LISA) relies on concepts and
instrumentation techniques to observe gravitational waves that are
not widely known in astrophysics or engineering for spaceflight. This
tutorial explains the basic scientific concepts, the mission concept,
the top-level architecture of the flight system and the character of
the resulting data for interested astrophysicists and engineers.
---------------------------------------------------------
Title: Demonstration of the zero-crossing phasemeter with a LISA
test-bed interferometer
Authors: Pollack, S. E.; Stebbins, R. T.
2006CQGra..23.4189P Altcode: 2006gr.qc.....5154P
The laser interferometer space antenna (LISA) is being designed to
detect and study in detail gravitational waves from sources throughout
the Universe such as massive black hole binaries. The conceptual
formulation of the LISA space-borne gravitational wave detector
is now well developed. The interferometric measurements between
the sciencecraft remain one of the most important technological and
scientific design areas for the mission. Our work has concentrated on
developing the interferometric technologies to create a LISA-like
optical signal and to measure the phase of that signal using
commercially available instruments. One of the most important goals
of this research is to demonstrate the LISA phase timing and phase
reconstruction for a LISA-like fringe signal, in the case of a high
fringe rate and a low signal level. We present current results of a
test-bed interferometer designed to produce an optical LISA-like fringe
signal previously discussed in Jennrich O, Stebbins R T, Bender P L and
Pollack S (<A>2001 Class. Quantum Grav. 18 4159 64</A>) and Pollack
S E, Jennrich O, Stebbins R T and Bender P (<A>2003 Class. Quantum
Grav. 20 S291 00</A>).
---------------------------------------------------------
Title: A demonstration of LISA laser communication
Authors: Pollack, S. E.; Stebbins, R. T.
2006CQGra..23.4201P Altcode: 2006gr.qc.....5155P
Over the past few years, questions have been raised concerning the
use of laser communications links between sciencecraft to transmit
phase information crucial to the reduction of laser frequency noise
in the LISA science measurement. The concern is that applying medium
frequency phase modulations to the laser carrier could compromise
the phase stability of the LISA fringe signal. We have modified the
table-top interferometer presented in Pollack and Stebbins (2006
Demonstration of the zero-crossing phasemeter with a LISA test-bed
interferometer Class. Quantum Grav.) by applying phase modulations to
the laser beams in order to evaluate the effects of such modulations
on the LISA science fringe signal. We have demonstrated that the phase
resolution of the science signal is not degraded by the presence of
medium frequency phase modulations.
---------------------------------------------------------
Title: Low-frequency active vibration isolation for advanced LIGO
Authors: Hua, Wensheng; Adhikari, R.; DeBra, Daniel B.; Giaime, Joseph
A.; Hammond, Giles D.; Hardham, C.; Hennessy, Mike; How, Jonathan P.;
Lantz, Brian T.; Macinnis, M.; Mittleman, R.; Richman, S.; Robertson,
Norna A.; Rollins, J.; Shoemaker, David H.; Stebbins, Robin T.
2004SPIE.5500..194H Altcode:
LIGO is dedicated to the detection of gravitational waves. To achieve
the design sensitivity of the proposed Advanced LIGO detectors, the
seismic isolation system is required to isolate the interferometer
mirrors from ground motion above 0.1 Hz. The dominant source of
motion above 0.1 Hz is the microseismic peaks near 0.15 Hz. The system
needs to isolate the payload from this motion by at least a factor of
five in all three translational degrees of freedom. Tilt-horizontal
coupling is the most challenging problem for seismic isolation below 1
Hz. Tilt-horizontal coupling results from the principle of equivalence:
inertial horizontal sensors cannot distinguish horizontal acceleration
from tilt motion. Tilt-horizontal coupling rises dramatically at low
frequencies, which makes low frequency isolation difficult. Several
techniques are used to address the tilt-horizontal coupling problem. The
isolation platform is designed to separate horizontal motions from tilt
motions. Feedback control to displacement sensors is used to command
the platform in all degrees of freedom. These sensors are "corrected"
by ground seismometers, using an optimal FIR filtering technique to
separate tilt noise from horizontal acceleration. With these techniques,
we obtained isolation factors of 10 to 20 simultaneously in all three
degrees of freedom at 0.15 Hz.
---------------------------------------------------------
Title: The Laser Interferometer Space Antenna: An Overview
Authors: Stebbins, Robin
2004APS..APR.L9001S Altcode:
The Laser Interferometer Space Antenna (LISA) is a joint ESA-NASA
mission that will explore the Universe for gravitational wave sources
between 0.1 mHz and 1 Hz. Anticipated sources of gravitational waves
include: the inspiral of supermassive black holes resulting from
galactic mergers; the inspiral of intermediate mass black holes; the
inspiral of compact objects into supermassive black holes; thousands
of close, compact binaries in our own Galaxy; and, possibly, density
fluctuations in the early universe if their (much more uncertain)
amplitude permits. LISA consists of three spacecraft orbiting the
Sun in a triangular formation. Gravitational waves are detected by
interferometrically monitoring the 5 million kilometer separations
between free-falling reference masses within the spacecraft. LISA
employs technology from Â"drag-freeÂ" control systems, spaceborne
accelerometers, microthrusters, interferometric distance-ranging and
precision measurements to measure strains of 10<SUP>-23</SUP> over
very long baselines.
---------------------------------------------------------
Title: Current error estimates for LISA spurious accelerations
Authors: Stebbins, R. T.; Bender, P. L.; Hanson, J.; Hoyle, C. D.;
Schumaker, B. L.; Vitale, S.
2004CQGra..21S.653S Altcode:
The performance of the LISA gravitational wave detector depends
critically on limiting spurious accelerations of the fiducial
masses. Consequently, the requirements on allowable acceleration levels
must be carefully allocated based on estimates of the achievable
limits on spurious accelerations from all disturbances. Changes in
the allocation of requirements are being considered, and are proposed
here. The total spurious acceleration error requirement would remain
unchanged, but a few new error sources would be added, and the
allocations for some specific error sources would be changed. In
support of the recommended revisions in the requirements budget,
estimates of plausible acceleration levels for 17 of the main error
sources are discussed. In most cases, the formula for calculating
the size of the effect is known, but there may be questions about
the values of various parameters to use in the estimates. Different
possible parameter values have been discussed, and a representative set
is presented. Improvements in our knowledge of the various experimental
parameters will come from planned experimental and modelling studies,
supported by further theoretical work.
---------------------------------------------------------
Title: LISA data reduction
Authors: Stebbins, R. T.; Bender, P. L.; Folkner, W. M.
2003AdSpR..32.1259S Altcode:
The passage of gravitational waves changes the arm lengths between
corners of the LISA spacecraft formation. These changes are detected
interferometrically and recorded as phase measurements. The time
series are reduced to reveal several signal types. First, the strong
periodic signals from all types of galactic binaries and any strong
chirped signals are identified by template fitting, and removed. Then
weak, periodic signals and poorly characterized signals (e.g., generic
bursts) are searched for. Next, weak signals with complex waveforms,
such as from compact objects orbiting massive black holes, are sought
with templates. Genetic algorithms, template structure or hierarchical
searches are used to efficiently search the very large parameter
space. Finally, backgrounds from galactic binaries, extragalactic
binaries and the Big Bang will/may be separable by their signatures.
---------------------------------------------------------
Title: Status of LISA phase measurement work in the US
Authors: Pollack, S. E.; Jennrich, O.; Stebbins, R. T.; Bender, P.
2003CQGra..20S.193P Altcode:
Currently there are two implementations for LISA phase measurement being
investigated in the United States. In this paper, we present the current
status of one of these implementations, the so-called zero-crossing
approach or stopwatch method. This method uses a technique of counting
and timing to make phase measurements. Herein we present a description
of the status of an experiment which produces an optical LISA-like
fringe which we use to test our phase meter.
---------------------------------------------------------
Title: Information about Intermediate Mass Black Hole Growth from
Gravitational Waves
Authors: Bender, P. L.; Stebbins, R. T.
2002AAS...201.5707B Altcode: 2002BAAS...34R1207B
It is likely that coalescences of roughly 10 M/sun and probably 100
M/sun black holes (BHs) with intermediate mass black holes (IMBHs)
occurred during the growth of the IMBHs in galactic nuclei and/or
globular clusters. Thus it is interesting to review the types of
associated gravitational wave (GW) signals that may be observable by
the Laser Interferometer Space Antenna (LISA), a planned joint ESA/NASA
mission, or by a later follow-on mission. For example, simulations
by Abel, Bryan and Norman indicate high masses for the first stars,
and a substantial fraction may form roughly 100 M/sun BHs. Madau and
Rees have suggested that, if this occurs, perhaps a few tens of them
can get to the nucleus in a Hubble time for Milky Way type galaxies. If
some arrive while IMBHs are growing there and don't plunge in rapidly,
they could give detectable GW signals. LISA could observe such signals
for 100 M/sun BHs coalescing with non-rotating 10,000 M/sun or larger
IMBHs even at z = 5, in agreement with the conclusions of Madau and
Rees. In the future, if a high-frequency LISA follow-on mission is
chosen, it might have 1 m diam. telescopes (instead of 0.3 m diam.),
10 W lasers, and 500,000 km arm lengths. With our present estimate of
the GW background due to extragalactic white dwarf binaries, such a
mission could observe 10 M/sun BHs coalescing with nonrotating IMBHs
at z = 5 for IMBH masses between about 1,500 and 20,000 M/sun. Similar
events could be observed out to z = 10 for Kerr IMBHs.
---------------------------------------------------------
Title: Seismic isolation for Advanced LIGO
Authors: Abbott, R.; Adhikari, R.; Allen, G.; Cowley, S.; Daw, E.;
DeBra, D.; Giaime, J.; Hammond, G.; Hammond, M.; Hardham, C.; How,
J.; Hua, W.; Johnson, W.; Lantz, B.; Mason, K.; Mittleman, R.; Nichol,
J.; Richman, S.; Rollins, J.; Shoemaker, D.; Stapfer, G.; Stebbins, R.
2002CQGra..19.1591A Altcode:
The baseline design concept for a seismic isolation component of the
proposed 'Advanced LIGO' detector upgrade has been developed with
proof-of-principle experiments and computer models. It consists of
a two-stage in-vacuum active isolation platform that is supported by
an external hydraulic actuation stage. Construction is underway for
prototype testing of a full-scale preliminary design.
---------------------------------------------------------
Title: Demonstration of the LISA phase measurement principle
Authors: Jennrich, O.; Stebbins, R. T.; Bender, P. L.; Pollack, S.
2001CQGra..18.4159J Altcode:
We present an experiment designed to test a type of phase measurement
system that could be used for LISA. The set-up consists of two parts:
one is an optical signal generator to provide an optical signal
similar to that expected for the interferometry in LISA. The other is
a phase-meter which uses a technique of counting and timing to measure
the phase of the signal as a function of time.
---------------------------------------------------------
Title: Interferometric Techniques for Gravitational Wave Detection
in Space
Authors: Stebbins, Robin T; Bender, Peter L.
2000STIN...0009820S Altcode:
The Laser Interferometer Space Antenna (LISA) mission will detect
gravitational waves from galactic and extragalactic sources, most
importantly those involving supermassive black holes. The primary
goal of this project is to investigate stability and robustness issues
associated with LISA interferometry. We specifically propose to study
systematic errors arising from: optical misalignments, optical surface
errors, thermal effects and pointing tolerances. This report covers
the first fiscal year of the grant, from January 1st to December
31st 1999. We have employed an optical modeling tool to evaluate the
effect of misplaced and misaligned optical components. Preliminary
results seem to indicate that positional tolerances of one micron
and angular tolerances of 0.6 millirad produce no significant effect
on the achievable contrast of the interference pattern. This report
also outlines research plans for the second fiscal year of the grant,
from January 1st to December 31st 2000. Since the work under NAG5-6880
has gone more rapidly than projected, our test bed interferometer is
operational, and can be used for measurements of effects that cause
beam motion. Hence, we will design, build and characterize a sensor
for measuring beam motion, and then install it. We are also planning
a differential wavefront sensor based on a quadrant photodiode as a
first generation sensor.
---------------------------------------------------------
Title: Active seismic isolation for enhanced LIGO detectors
Authors: Giaime, Joseph; Lantz, Brian; Debra, Daniel; How, Jonathan;
Hardham, Corwin; Richman, Sam; Stebbins, Robin
2000AIPC..523..300G Altcode: 2000grwa.conf..300G
The levels of seismic isolation needed for LIGO II will require a
dramatic technological shift from the systems used in the initial
LIGO detector. To take advantage of the improved thermal noise of a 30
kg test mass made of high-Q material and suspended with fused silica
fibers, one must attenuate the ground motion by more than 10 orders
of magnitude at 10 Hz. Aggressive active isolation of ground motion to
reduce the root-mean-squared ground displacement and the displacement
noise in the gravitational wave band, coupled with multiple pendulum
suspensions, can make this possible. We will describe the mechanical
design for such a system, and discuss the issues of active control
that confront this endeavor. .
---------------------------------------------------------
Title: Separation of LISA Galactic and Extragalactic Signals
Authors: Bender, Peter L.; Hils, Dieter; Stebbins, Robin T.
2000APS..APRH20013B Altcode:
Data obtained by the Laser Interferometer Space Antenna (LISA) is
expected to include gravitational wave signals from several types of
sources involving massive black holes at cosmological distances. In
addition, there will be a very large number of signals from short period
galactic binaries. For 1 year of observations, the average number of
galactic binaries per frequency bin will be large enough at frequencies
below 1 mHz so that most of their signals cannot be resolved. At higher
frequencies, above roughly 3 mHz, most individual galactic signals
can be solved for and removed from the data record. Studies have been
started to investigate, for frequencies from roughly 1 to 10 mHz, how
much information about the extragalactic black hole sources will be lost
because of having to solve for the galactic sources. An axisymmetric
but fairly realistic model is being used for the distribution of
binaries in the galaxy. It probably will be desirable to subtract out
some sources whose reality and signal parameters are only moderately
certain, but whose frequency characteristics differ from the massive
black hole signals of interest.
---------------------------------------------------------
Title: What Information May Gravitational Waves Carry About Early
Galaxies?
Authors: Bender, Peter L.; Hils, Dieter; Stebbins, Robin T.
1999ASPC..182..539B Altcode: 1999gady.conf..539B
No abstract at ADS
---------------------------------------------------------
Title: Progress on Low-Frequency Active Vibration Isolation
Authors: Richman, S. J.; Giaime, J. A.; Stebbins, R. T.; Bender,
P. L.; Faller, J. E.
1999magr.meet.1066R Altcode:
No abstract at ADS
---------------------------------------------------------
Title: LISA operations and sensitivity
Authors: Stebbins, R. T.; LISA Team
1998AIPC..456...17S Altcode: 1998lain.conf...17S
The three LISA spacecraft must monitor changes in their relative
separation to about 10 pm. The various operating modes during the
mission lifetime will be summarized, and the science mode will be
described in detail. The science operations involve the optical system,
the attitude and position control system, the on-board processing for
signal extraction, telemetry and ground operations. The instrumental
origins of the anticipated LISA sensitivity curve will also be
described.
---------------------------------------------------------
Title: Experimental demonstration of some aspects of LISA
interferometry
Authors: Giaime, J. A.; Stebbins, R. T.; Bender, P. L.; Faller, J. E.;
Hall, J. L.
1998AIPC..456..169G Altcode: 1998lain.conf..169G
Plans are described to experimentally demonstrate at JILA a possible
phase measurement technique for use in LISA interferometry. This
demonstration will include use of a compact system for fringe generation
and photodetection with realistic beam powers in a Mach-Zehnder
interferometer, and development of a stable digital fringe phase
measurement system.
---------------------------------------------------------
Title: Possible use of a narrow-field star tracker on the New
Millennium SSI mission
Authors: Bender, Peter L.; Stebbins, Robin T.; Folkner, William M.
1998SPIE.3350..626B Altcode:
A separated spacecraft interferometer (SSI) demonstration mission
with three spacecraft has been proposed for flight under the NASA New
Millennium Technology Development Program. Both the rotation rate
of the interferometer about the normal to the plane containing the
three spacecraft and the orientation in the plane must be determined
accurately in order to permit the detection of white light fringes
from sources that have visual magnitudes as high as possible. It
presently is planned to use signals from tracking the science object
plus other auxiliary information to determine the interferometer
rotation rate d(theta) /dt and the angular position (theta) . We have
investigated a possible supplementary approach that makes use of a
combined beacon tracker and narrow-field star tracker on one of the
two collector spacecraft. A very small beacon mounted on the other
collector spacecraft can be viewed with respect to a reference star
nearly 180 degrees away to determine d(theta) /dt and (theta) for the
interferometer. Beacon/star tracker observations over roughly an hour
appear sufficient to determine the sweep rate for starlight fringes
in the interferometer to adequate accuracy and to detect the fringes.
---------------------------------------------------------
Title: Gravitational Wave Frequency Range for the LISA Mission
Authors: Folkner, W. M.; Bender, P. L.; Stebbins, R. T.
1998AAS...192.1708F Altcode: 1998BAAS...30..843F
Studies of the Laser Interferometer Space Antenna mission are being
pursued actively both in Europe and in the US. The present mission
design calls for three spacecraft to be launched on a single Delta II
launch vehicle and placed in an equilateral triangle configuration about
20 degrees behind the Earth in orbit around the Sun. Laser heterodyne
measurements made over the 5 million km sides of the triangle permit
the detection and detailed study of gravitational wave signals. The
frequency range discussed for LISA usually has been limited to 0.0001
to 1 Hz because of reliance on passive thermal isolation to keep
noise due to temperature fluctuations in the most sensitive part of
the payload small. However, the possibility of actively controlling
the temperature of the thermal shield around the payload is now being
investigated. The expected improvement in the LISA sensitivity below
0.0001 Hz will be discussed. This would extend the useful sensitivity
to include possible sources with larger masses, such as the coalescence
of massive black holes after galaxy mergers.
---------------------------------------------------------
Title: On the Origin of Solar Oscillations
Authors: Goode, Philip R.; Strous, Louis H.; Rimmele, Thomas R.;
Stebbins, Robin T.
1998ApJ...495L..27G Altcode: 1998astro.ph..1008G
We have made high-resolution observations of the Sun in which we
identify individual sunquakes and see power from these seismic events
being pumped into the resonant modes of vibration of the Sun. A typical
event lasts about 5 minutes. We report the physical properties of
the events and relate them to theories of the excitation of solar
oscillations. We also discuss the local seismic potential of these
events.
---------------------------------------------------------
Title: LISA Mission Concept Study, Laser Interferometer Space Antenna
for the Detection and Observation of Gravitational Waves
Authors: Folkner, W. M.; Bender, P. L.; Stebbins, R. T.
1998STIN...0055623F Altcode:
This document presents the results of a design feasibility study for
LISA (Laser Interferometer Space Antenna). The goal of LISA is to
detect and study low-frequency astrophysical gravitational radiation
from strongly relativistic regions. Astrophysical sources potentially
visible to LISA include extra-galactic massive black hole binaries
at cosmological distances, binary systems composed of a compact star
and a massive black hole, galactic neutron star-black hole binaries,
and background radiation from the Big Bang. The LISA mission will
comprise three spacecraft located five million kilometers apart forming
an equilateral triangle in an Earth-trailing orbit. Fluctuations in
separation between shielded test masses located within each spacecraft
will be determined by optical interferometry which determines the
phase shift of laser light transmitted between the test masses.
---------------------------------------------------------
Title: Getting astrophysical information from LISA data
Authors: Stebbins, R. T.; Bender, P. L.; Folkner, W. M.
1997CQGra..14.1499S Altcode:
No abstract at ADS
---------------------------------------------------------
Title: LISA data acquisition
Authors: Stebbins, R. T.; Bender, P. L.; Folkner, W. M.; LISA
Science Team
1996CQGra..13A.285S Altcode:
The method for measuring changes in the lengths of the three arms
for the LISA gravitational-wave detector is described. Accurate phase
measurements are required on signals with Doppler shifts of about 1
MHz for the two main arms of the interferometer, and up to 15 MHz for
the third arm. This is accomplished by shifting the signal frequencies
down to near 100 kHz, filtering and then timing zero crossings of the
signals. The basic methods for correcting for the laser phase noise
and for phase noise in the ultra-stable oscillators used to derive
various radio frequencies are described briefly. The corrections are
made on the spacecraft, before the data are telemetred to the ground.
---------------------------------------------------------
Title: Sensitivity of the LISA Gravitational Wave Mission
Authors: Ward, H.; Bender, P.; Faller, J. E.; Stebbins, R. T.
1996APS..MAY..E901W Altcode:
The sensitivity achievable by the Laser Interferometer Space Antenna
(LISA) will be discussed (see also abstracts by Stebbins et al and by
Bender and Hils). Below about 1 mHz, the sensitivity will be limited
mainly by spurious accelerations of the proof mass in each spacecraft
and by a random superposition of signals from many short period galactic
binaries. At higher frequencies, the main limitations will come from
shot noise in determining the difference in length of the interferometer
arms and from fluctuations in the pointing of the laser beams. Hundreds
to thousands of galactic binaries resolved in frequency and direction
will be detectable throughout the galaxy. A few known sources will be
included. One possible type of source is black hole-massive black hole
(BH-MBH) binaries, with periapsis speeds of about half the speed of
light, very rapidly precessing elliptical orbits, and possible fast
orbit plane precession around Kerr MBHs. The observation of such signals
or of those from MBH-MBH binaries would permit extremely strong tests
of the dynamical predictions of general relativity.
---------------------------------------------------------
Title: The LISA Gravitational Wave Mission
Authors: Stebbins, R. T.; Bender, P. L.; Faller, J. E.; Folkner,
W. M.; Ward, H.
1996APS..MAY.J1506S Altcode:
The Laser Interferometer Space Antenna (LISA) is a mission designed for
detailed studies of gravitational waves with frequencies of roughly 0.1
mHz to 1 Hz. Gravitational waves will be detected by interferometrically
monitoring the relative distances between proof masses in different
spacecraft, separated by 5× 10^6 km. LISA will detect strains as low
as 10<SUP>-23</SUP> with a 1 yr observation time and a S/N ratio of
5. The sensitivity will be sufficient to detect many gravitational
wave sources which cannot be readily observed by any other means. The
3-arm interferometer consists of 6 spacecraft orbiting the Sun, with
two at each vertex of an equilateral triangle. Proof mass disturbances
are kept small by a drag-free system and the benign environment of
solar orbit. LISA was selected in 1994 as a Cornerstone mission in
the proposed ESA Horizon 2000 Plus program. Technology development
studies for LISA are being started by ESA. Investigations of possible
US contributions to LISA currently are in progress under a NASA program
for studies of new mission concepts in astrophysics.
---------------------------------------------------------
Title: The Sun's Acoustic Spectrum and Normal Mode Parameters
Authors: Stebbins, R. T.; Hill, F.; Stark, P. B.; GONG Data Reduction
Team; GONG Analysis Team
1996AAS...188.5306S Altcode: 1996BAAS...28..904S
GONG seeks to measure the frequencies, amplitudes and line widths of
the Sun's acoustic normal modes. The Project estimates these parameters
for more than 250,000 acoustic modes of the Sun from every 36 day-long
set of data. Data from the network are archived, calibrated, reduced
to several science products and made available for distribution to
researchers at the pace of observations. GONG also produces magnetograms
and temporally filtered solar images for convective velocity and
magnetic field studies. The frequency resolution of a single data set
is 0.321 mu Hz. For m- averaged frequencies the median formal error
is 0.044 mu Hz, and the associated median fractional frequency error
is 1.6 x 10(-5) . Results from concatenated data sets are now becoming
available. For a three-year data set, the fractional error is expected
to be 3 x 10(-6) , providing the highest quality helioseismic frequency
measurements to date. Examples of power spectra and mode parameters
will be shown. To demonstrate the reliability of the initial GONG
frequencies, m-averaged frequency measurements will be compared with
other helioseismic data sets. The mean systematic variations among
the data sets are 0.03 to 0.08 mu Hz. The differences arise from a
combination of systematic errors, random errors, and possible changes
in solar structure and dynamics. Error sources will be discussed.
---------------------------------------------------------
Title: The Solar Acoustic Spectrum and Eigenmode Parameters
Authors: Hill, F.; Stark, P. B.; Stebbins, R. T.; Anderson, E. R.;
Antia, H. M.; Brown, T. M.; Duvall, T. L., Jr.; Haber, D. A.;
Harvey, J. W.; Hathaway, D. H.; Howe, R.; Hubbard, R. P.; Jones,
H. P.; Kennedy, J. R.; Korzennik, S. G.; Kosovichev, A. G.; Leibacher,
J. W.; Libbrecht, K. G.; Pintar, J. A.; Rhodes, E. J., Jr.; Schou, J.;
Thompson, M. J.; Tomczyk, S.; Toner, C. G.; Toussaint, R.; Williams,
W. E.
1996Sci...272.1292H Altcode:
The Global Oscillation Network Group (GONG) project estimates
the frequencies, amplitudes, and linewidths of more than 250,000
acoustic resonances of the sun from data sets lasting 36 days. The
frequency resolution of a single data set is 0.321 microhertz. For
frequencies averaged over the azimuthal order m, the median formal
error is 0.044 microhertz, and the associated median fractional error
is 1.6 x 10<SUP>-5</SUP>. For a 3-year data set, the fractional error
is expected to be 3 x 10<SUP>-6</SUP>. The GONG m-averaged frequency
measurements differ from other helioseismic data sets by 0.03 to 0.08
microhertz. The differences arise from a combination of systematic
errors, random errors, and possible changes in solar structure.
---------------------------------------------------------
Title: Multiresolution-element imaging of extrasolar Earthlike planets
Authors: Bender, Peter L.; Stebbins, Robin T.
1996JGR...101.9309B Altcode:
It has been suggested recently that imaging of extrasolar Earthlike
planets should be considered as a possible future goal of the NASA
space program. As an aid to discussing what would be required in order
to undertake imaging, a partial design is described for a separated
spacecraft interferometer which could achieve images in the visible
with 10 resolution elements across the planet. Between 15 and 25 large
collector telescopes or clusters of telescopes spread out over roughly
a 200-km baseline in solar orbit at 1 AU from the Sun or possibly in
high Earth orbit are required. A very preliminary approach to the use of
multispectral remote sensing techniques is discussed also. Finally, the
generalization of this approach to larger numbers of resolution elements
across the planet is considered. Clearly, imaging is possible only
if the truly staggering problem of avoiding the 10<SUP>10</SUP> times
stronger scattered light from the nearby star can be overcome. However,
even if this can be done, the amount and precision of the required
hardware for even poor-quality images appears to present an obstacle
to such a program which would be extremely difficult to overcome.
---------------------------------------------------------
Title: Active/Passive Vibration Isolation at 1 HZ and Above Part II:
Main Stages
Authors: Richman, S. J.; Newell, D. B.; Stebbins, R. T.; Bender,
P. L.; Faller, J. E.
1996magr.meet.1426R Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Thermal Stability Analysis for a Heliocentric Gravitational
Radiation Detection Mission
Authors: Folkner, W. M.; McElroy, P.; Miyake, R.; Bender, P. L.;
Stebbins, R. T.; Supper, W.
1996magr.meet.1655F Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Active/Passive Vibration Isolation at 1Hz and Above Part I:
Single Stage, Six Degrees of Freedom
Authors: Newell, D. B.; Richman, S. J.; Stebbins, R. T.; Nelson,
P. G.; Mason, J. E.; Bender, P. L.; Faller, J. E.
1996magr.meet.1421N Altcode:
No abstract at ADS
---------------------------------------------------------
Title: The LISA Gravitational Wave Mission
Authors: Stebbins, R. T.; Bender, P. L.; Faller, J. E.; Hils, D.;
Folkner, W. M.
1995AAS...187.7105S Altcode: 1995BAAS...27R1384S
The Laser Interferometer Space Antenna (LISA) is a mission designed
for detailed studies of gravitational waves with frequencies of roughly
0.0001 to 1 Hz. It is a Cornerstone mission in the proposed ESA Horizon
2000 Plus program. Investigations of possible US contributions to LISA
currently are in progress under the NASA program for studies of new
mission concepts in astrophysics. LISA is a formation of 6 spacecraft
in the shape of an equilateral triangle 5 million km on a side, with
2 spacecraft at each vertex. The formation is in orbit around the
Sun, following about 20(deg) behind the Earth. Orbital parameters
are chosen so that the distances between the spacecraft stay nearly
constant for years. Each spacecraft is made drag-free by keeping
it centered on a carefully shielded test mass at its center. Laser
distance measurements are made between the test masses using roughly
0.5 W per beam and about 40 cm diameter telescopes. Laser phase noise
can be determined by observing the apparent changes in the 5 million
km arm lengths, since the real variations in the arm lengths at the
frequencies of interest are very small. The desired gravitational
wave signals are obtained from the corrected differences in the arm
lengths. For 1 yr of observations and a S/N of 5, the LISA sensitivity
reaches its maximum of 10(-23) at frequencies of 0.001 to 0.03 Hz. This
sensitivity is sufficient to detect sources such as a 5 to 10M_sun
black hole orbiting around and coalescing with a roughly 10(6M_sun)
black hole at z=1. Scenarios in which such events would be observed
appear to be quite plausible if 0.01% or more of the stars in the
cusps around supermassive black holes in galactic nuclei are black
holes. Coalescences of two supermassive black holes after galactic or
pregalactic mergers also may be observed. For short period galactic
binaries, hundreds to thousands of individual sources will be resolved
and their distribution in the galaxy determined.
---------------------------------------------------------
Title: Dark Lanes in Granulation and the Excitation of Solar
Oscillations
Authors: Rimmele, T. R.; Goode, P. R.; Strous, L. H.; Stebbins, R. T.
1995ESASP.376b.329R Altcode: 1995help.confP.329R; 1995soho....2..329R
No abstract at ADS
---------------------------------------------------------
Title: 15-m laser-stabilized imaging interferometer
Authors: Stebbins, Robin T.; Bender, Peter L.; Chen, Che Jen; Page,
Norman A.; Meier, D.; Dupree, A. K.
1995SPIE.2477...31S Altcode:
The LAser-Stabilized Imaging Interferometer (LASII) concept is being
developed as an astronomical telescope for the next generation of
optical resolution beyond Hubble Space Telescope (HST). The essential
ingredients are: a rigid and stable structure to minimize mechanical
and thermal distortion, active control of the optical geometry by
a laser metrology system, a self-deploying structure fitting into a
single launch vehicle, and ultraviolet operation. We have modified
earlier design concepts to fit the scale of an intermediate sized
NASA mission. Our present design calls for 24 0.5 m apertures in a
Mills Cross configuration, supported on four trusses. A fifth truss
perpendicular to the primary surface would support the secondary mirror
and the laser metrology control points. Either separate interferometers
or two guide telescopes would track guide stars. This instrument would
have about 6 times the resolution of HST in the visible and the same
collecting area. The resolution would reach 2.5 mas at 150 nm. The
primary trusses would fold along the secondary truss for launch, and
automatically deploy on orbit. Possible orbits are sun-synchronous at
900 km altitude, high earth orbit or solar orbit. Infrared capability
could be included, if desired.
---------------------------------------------------------
Title: Dark Lanes in Granulation and the Excitation of Solar
Oscillations
Authors: Rimmele, Thomas R.; Goode, Philip R.; Harold, Elliotte;
Stebbins, Robin T.
1995ApJ...444L.119R Altcode:
We made simultaneous, high-resolution observations of the Sun's
granulation and solar acoustic events in the photosphere. We find that
the acoustic events, which are a local by-product of the excitation
of solar oscillations (Goode, Gough, & Kosovichev 1992), occur
preferentially in the dark, intergranular lanes. At the site of
a typical acoustic event the local granulation becomes darker over
several minutes leading up to the event with a further, abrupt darkening
immediately preceding the peak of the event. Further, the stronger
the acoustic event the darker the granulation. Thus, the excitation of
solar oscillations seems more closely associated with the rapid cooling
occurring in the upper convection layer, rather than the overshooting of
turbulent convection itself. We find no substantial role for so-called
'exploding' granules in the excitation of solar oscillations.
---------------------------------------------------------
Title: Photospheric Wave Behavior
Authors: Stebbins, R. T.; Rimmele, T. R.; Goode, P. R.
1995ASPC...76..354S Altcode: 1995gong.conf..354S
No abstract at ADS
---------------------------------------------------------
Title: The Global Oscillation Network Group Site Survey - Part One
Authors: Hill, Frank; Fischer, George; Grier, Jennifer; Leibacher,
John W.; Jones, Harrison B.; Jones, Patricia P.; Kupke, Renate;
Stebbins, Robin T.
1994SoPh..152..321H Altcode:
The Global Oscillation Network Group (GONG) Project is planning to place
a set of instruments around the world to observe solar oscillations as
continuously as possible for at last three years. The Project has now
chosen the sites that will comprise the network. This paper describes
the methods of data collection and analysis that were used to make
this decision.
---------------------------------------------------------
Title: The Global Oscillation Network Group Site Survey - Part Two
Authors: Hill, Frank; Fischer, George; Forgach, Suzanne; Grier,
Jennifer; Leibacher, John W.; Jones, Harrison P.; Jones, Patricia
B.; Kupke, Renate; Stebbins, Robin T.; Clay, Donald W.; Ingram,
Robert E. L.; Libbrecht, Kenneth G.; Zirin, Harold; Ulrichi, Roger
K.; Websteri, Lawrence; Hieda, Lester S.; Labonte, Barry J.; Lu,
Wayne M. T.; Sousa, Edwin M.; Garcia, Charles J.; Yasukawa, Eric
A.; Kennewell, John A.; Cole, David G.; Zhen, Huang; Su-Min, Xiao;
Bhatnagar, Arvind; Ambastha, Aashok; Al-Khashlan, Abdulrahman Sa'ad;
Abdul-Samad, Muhammad-Saleh; Benkhaldoun, Zouhair; Kadiri, Samir;
Sánchez, Francisco; Pallé, Pere L.; Duhalde, Oscar; Solis, Hernan;
Saá, Oscar; González, Ricardo
1994SoPh..152..351H Altcode:
The Global Oscillation Network Group (GONG) Project will place a
network of instruments around the world to observe solar oscillations as
continuously as possible for three years. The Project has now chosen the
six network sites based on analysis of survey data from fifteen sites
around the world. The chosen sites are: Big Bear Solar Observatory,
California; Mauna Loa Solar Observatory, Hawaii; Learmonth Solar
Observatory, Australia; Udaipur Solar Observatory, India; Observatorio
del Teide, Tenerife; and Cerro Tololo Interamerican Observatory, Chile.
---------------------------------------------------------
Title: Observation of Impulsive Acoustic Events and the Excitation
of Solar Oscillations
Authors: Restaino, Sergio R.; Stebbins, Robin T.; Goode, Philip R.
1993ApJ...408L..57R Altcode:
The 5 minute solar oscillation has been exploited in numerous seismic
studies in which internal properties of the sun have been inferred. It
is generally regarded that these modes are excited by turbulent
convection in the sun's outermost layers. We observe the oscillatory
wakes caused by impulsive events, related to those described in 1909
by Lamb. These correspond to the events modeled by Goode et al. (1992)
which they associate with excitation of the global 5-min oscillations.
---------------------------------------------------------
Title: Observation of impulsive acoustic events and the excitation
of solar oscillations
Authors: Restaino, Sergio R.; Stebbins, Robin T.; Goode, Philip R.
1992njit.rept.....R Altcode:
The five-minute solar oscillation has been exploited in numerous seismic
studies in which internal properties of the Sun have been inferred. It
is generally regarded that these modes are excited by turbulent
convection in the Sun's outermost layers. The oscillatory wakes caused
by impulsive events were observed, matching those described by Lamb
(1909). These correspond to the events modeled by Goode, et al., which
they associate with excitation of the global five-minute oscillations.
---------------------------------------------------------
Title: Movies of Velocity and Acoustic Flux in the Solar Photosphere
Authors: Stebbins, R. T.; Restaino, S. R.; Goode, P. R.
1992AAS...180.0605S Altcode: 1992BAAS...24..737S
CCD images of FeI 5434 Angstroms line profiles have previously
been collected and analyzed for the average characteristics of wave
propagation in the photosphere. The previous analysis determined the
velocity at nine depths in the spectral line and 100 horizontal spatial
points spanning 70 arc sec. Time series of these velocity frames,
lasting 37 minutes, have been Fourier transformed and filtered to
pass the five minute modes of the Sun. Through the Hilbert transform
and the analytic signal, the instantaneous velocity amplitude and
phase were computed at every point in the three dimensional space
of altitude, horizontal slit position and time. These data have been
further processed to create color-contour maps of vertical acoustic
propagation at each time sample. Velocity amplitude, velocity phase,
kinetic energy density and acoustic flux are all mapped. Time series of
these maps have been assembled into a movie which shows the evolution of
vertical acoustic propagation. This movie is a complete visualization
of sound waves in the photosphere, based on observation. The amplitude
and kinetic energy density behaves as one might expect in the presence
of the solar p-modes. However, the phase and acoustic flux have
characteristic spatial and temporal scales which are very different
from the amplitude. For example, upward and downward flux may occur
in the same amplitude structure at different times, or at the same
time. These results are consistent with the localized model of p-mode
excitation advanced by Goode, Gough and Kosovichev.
---------------------------------------------------------
Title: Gravitational radiation observations on the moon
Authors: Stebbins, R. T.; Armstrong, J. W.; Bender, P. L.; Drever,
R. W. P.; Hellings, R. W.; Saulson, P. R.
1990AIPC..207..637S Altcode: 1990am...proc..637S
A Laser-Interferometer Gravitational-Wave Observatory (LIGO) is
planned for operation in the United States, with two antennas
separated by several thousand kilometers. Each antenna would
incorporate laser interferometers with 4 km arm lengths, operating
in vacuum. The frequency range covered initially would be from a few
tens of Hz to a few kHz, with possible extension to lower frequencies
later. Similar systems are likely to be constructed in Europe, and
there is a possibility of at least one system in Asia or Australia. It
will be possible to determine the direction to a gravitational wave
source by measuring the difference in the arrival times at the various
antennas for burst signals or the phase difference for short duration
nearly periodic signals. The addition of an antenna on the Moon,
operating in support of the Earth-based antennas, would improve the
angular resolution for burst signals by about a factor 50 in the plane
containing the source, the Moon, and the Earth. This would be of major
importance in studies of gravitational wave sources. There is also
a possibility of somewhat lower noise at frequencies near 1 Hz for a
lunar gravitational wave antenna, because of lower gravity gradient
noise and microseismic noise on the Moon. However, for frequencies
near 0.1 Hz and below, a 107 km laser gravitational wave antenna in
solar orbit would be much more sensitive.
---------------------------------------------------------
Title: A lunar gravitational wave antenna using a laser interferometer
Authors: Stebbins, R. T.; Bender, P. L.
1990AIPC..202..188S Altcode: 1990palb.work..188S
A moon-based laser interferometer for detecting gravitational radiation
could detect signals in the band 10-1 to 104 Hz. A preliminary
evaluation of the noise budget for an optimistic antenna design is
reported here and compared to that for other planned gravitational wave
interferometers. Over most of the frequency range, the sensitivity is
controlled by the thermal noise in the test mass suspensions. From
roughly 3 to a few hundred Hertz, it is about the same as the
sensitivity expected in terrestrial antennas of the same construction,
which will have been operating for at least a decade. Below 0.3 Hz,
a proposed space-based interferometer, designed for operation down to
10-5 Hz, would have better sensitivity. As pointed out by others, the
most important role of a lunar antenna would be the improved angular
resolution made possible by the long baseline to terrestrial antennas.
---------------------------------------------------------
Title: An Algorithm for Removing Pattern Noise in Reticons
Authors: Stebbins, R. T.; Restaino, S. R.
1990BAAS...22R.887S Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Optical interferometer in space.
Authors: Bender, Peter L.; Faller, J. E.; Hall, J. L.; Hils, D.;
Stebbins, R. T.; Vincent, Mark A.
1989NASCP3046...80B Altcode: 1989rges.rept...80B
The present design concepts for a Laser Gravitational-Wave Observatory
in Space are described. Laser heterodyne distance measurements are made
between test masses located in three spacecraft separated by roughly
10<SUP>6</SUP>km. The science objectives are: to measure discrete
sinusoidal gravitational wave signals from individual sources with
periods of 1 second to 1 day; to measure the stochastic background due
to unresolved binaries; and to search for gravitational wave pulses
with periods longer than 1 second from possible exotic sources such
as gravitational collapse of very massive objects.
---------------------------------------------------------
Title: Disturbance Reduction Techniques for a Laser Gravitational
Wave Observatory in Space
Authors: Bender, P. L.; Faller, J. E.; Hils, D.; Stebbins, R. T.
1989grg..conf..566B Altcode:
No abstract at ADS
---------------------------------------------------------
Title: a 1-TO-10-HZ Prototype Isolation System for Gravitational
Wave Interferometers and Thermal Noise Measurements
Authors: Stebbins, R. T.; Bender, P. L.; Faller, J. E.; Newell, D. B.;
Speake, C. C.
1989grg..conf..585S Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Wave Behavior in the Solar Photosphere - a Comparison of
Theory and Observation
Authors: Marmolino, Ciro; Stebbins, Robin T.
1989SoPh..124...23M Altcode:
We report detailed comparisons between theoretical and empirical
eigenfunctions of velocity and intensity for the 5-min modes in the
photosphere. The comparison process is accomplished by obtaining
synthetic profiles of the FeI λ5434 Å line in the presence
of waveforms given by dynamical calculations and then applying
a common procedure of reduction both to the observed and to the
synthetic data. For the velocity waveforms, our results show a general
agreement between theory and observations together with some systematic
differences; in particular the theory systematically underestimates the
observations in the low photosphere. These systematic differences are
stressed by the intensity results since both the computed amplitudes
and phases appear to be wrong in the deeper layers.
---------------------------------------------------------
Title: An antenna for laser gravitational-wave observations in space
Authors: Faller, J. E.; Bender, P. L.; Hall, J. L.; Hils, D.; Stebbins,
R. T.; Vincent, M. A.
1989AdSpR...9i.107F Altcode: 1989AdSpR...9..107F
Progress during the past two years on a proposed Laser
Gravitational-Wave Observatory in Space (LAGOS) is discussed. Calculated
performance for a 10<SUP>6</SUP> km sized antenna over the frequency
range of 10<SUP>-5</SUP> to 1 Hz is given. The sensitivity from
10<SUP>-3</SUP> to 10<SUP>-1</SUP> Hz is expected to be 1 ×
10<SUP>-21</SUP>/Hz<SUP>0.5</SUP>. Noise sources such as accelerations
of the drag-free test masses by random molecular impacts and by
fluctuations in the net thermal radiation pressure will limit the
sensitivity at lower frequencies. The scientific objectives are the
observation of CW gravitational waves from large numbers of binary
systems and the detection of pulses which may have been emitted during
the period of galaxy formation.
---------------------------------------------------------
Title: The 5-minute oscillation in the solar photosphere - Theoretical
behaviour versus observations
Authors: Marmolino, C.; Stebbins, R. T.
1989MmSAI..60...71M Altcode:
Calculations are used to explore how theoretical waveforms for the
five-minute solar oscillation reproduce the observed behavior of
the solar Fe I 5434 A line. Comparison of theoretical and empirical
velocity eigenfunctions shows some systematic differences in a framework
of general agreement. The theory systematically underestimates the
observations in both amplitude and phase shift in the low photosphere;
the differences between the various theoretical treatments is much
smaller than the difference between theory and observation. The
intensity agreement is poor, with the theoretical treatments again
differing much less with each other than with observation. These results
are evidence for systematic problems with the assumptions involved in
the calculation of the waveforms pertaining to the deeper layers of
the photosphere.
---------------------------------------------------------
Title: Preliminary Optical Design for a Laser Gravitational Wave
Antenna in Space
Authors: Bender, P. L.; Faller, J. E.; Hall, J. L.; Hills, D.;
Stebbins, R.
1988soae.conf...12B Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Waves in the Solar Photosphere
Authors: Stebbins, Robin; Goode, Philip R.
1987SoPh..110..237S Altcode:
Time-sequences of line profile data have been subjected to a unique
analysis which produces an amplitude and phase of the velocity and
intensity at several line depths for each time sample and spatial
point on the Sun. The data have been filtered to pass only the
frequencies and spatial wavenumbers of the 5-min band. Yet, a secondary
oscillation emerges, the phase of which propagates downward. Empirical
eigenfunctions for velocity and intensity are given, and the kinetic
energy flux is computed.
---------------------------------------------------------
Title: Proposed studies of a 30-meter imaging interferometer concept
Authors: Stebbins, R. T.; Bender, P. L.; Faller, J. E.
1987ESASP.273...85S Altcode: 1987ois..work...85S
An imaging interferometer in space based on the use of 15 m sections of
graphite-epoxy truss structure to form the basic mechanical support
system is suggested. One simple design is a Y-shaped array of 3
coplanar arms, each 15 m long and 1.5 m in diameter, together with a
perpendicualr mast of similar length. Roughly 15 observing telescopes
of 0.5 m diameter would be used, with laser interferometers controlling
the optical pathlengths. The total mass of the imaging interferometer
is 3000 kg. With this design, the entire interferometer can be carried
to orbit with a single STS launch and then deployed. The interferometer
could be operated either in a fully illuminated Sun-synchronous orbit
at 1400 km altitude or loosely attached to the Space Station.
---------------------------------------------------------
Title: A Simple Irradiance Monitor for Testing Solar Global
Oscillation Network Sites
Authors: Fischer, G.; Hill, F.; Jones, W.; Leibacher, J.; McCurnin,
W.; Stebbins, R.; Wagner, J.
1986SoPh..103...33F Altcode:
We describe a simple irradiance monitor intended for use in assessing
the suitability of candidate sites for a worldwide network of small
solar telescopes. The network will observe the Sun as continuously
as possible in order to provide high quality solar oscillation data
with low diurnal sidelobe contamination and high temporal frequency
resolution.
---------------------------------------------------------
Title: Observation of Solar Brightness Oscillations at the South Pole
Authors: Stebbins, R. T.; Ronan, R.; Arrambide, M.
1985AnJUS..20..219S Altcode:
No abstract at ADS
---------------------------------------------------------
Title: A preliminary report on brightness oscillation observations
made at South Pole during the 1982-83 Austral Summer
Authors: Stebbins, R.
1984MmSAI..55..229S Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Observations of Solar Oscillations at the South Pole
Authors: Stebbins, R. T.; Mann, R.
1984AnJUS..18..268S Altcode:
No abstract at ADS
---------------------------------------------------------
Title: The measurement of long-period oscillations at Sacramento
Peak Observatory and South Pole
Authors: Stebbins, R.; Wilson, C.
1983SoPh...82...43S Altcode: 1983IAUCo..66...43S
A program to measure long-period brightness oscillations at the solar
limb has been pursued at Sacramento Peak Observatory for several
years. Past improvements in observing technique and data analysis are
reviewed. The encouraging results aid in the verification of the reality
and the origin of oscillatory signals. However, the main stumbling block
to this and other observational programs is the length of observing
sequences imposed by the day/night cycle. The South Pole has received
considerable attention as a site where extended observations might be
possible. Currently, the Sacramento Peak program is developing a South
Pole telescope designed for the observing technique and data analysis
proven in Sunspot. A review of pertinent South Pole site parameters
is given here for other workers who may be considering South Pole
observations. Observing sequences longer than 150 hr are possible,
though rare. Data sets of this duration are very attractive for solar
oscillation studies.
---------------------------------------------------------
Title: Observation of five-minute-period gravity waves in the solar
photosphere
Authors: Stebbins, R. T.; Goode, Philip R.; Hill, Henry A.
1983SoPh...82..163S Altcode: 1983IAUCo..66..163S
Vertically propagating traveling waves have been observed in the
solar photosphere. These waves have a period of 278 ± 41 seconds
and a vertical phase velocity of about 2 km s<SUP>-1</SUP>. It is
noted that these waves also have approximately the same period as the
well-studied five-minute-period acoustic mode, which is evanescent in
the photosphere. The only consistent interpretation of the traveling
waves implies that they are gravity waves. About half the time the
gravity waves are outgoing, while the remainder of the time they
are ingoing.
---------------------------------------------------------
Title: Observations of Solar Oscillations at the South Pole
Authors: Stebbins, R. T.; Mann, R.
1983AnJUS..18..268S Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Observation of nonacoustic, 5 minute period, vertical traveling
waves in the photosphere of the sun
Authors: Hill, H. A.; Goode, P. R.; Stebbins, R. T.
1982ApJ...256L..17H Altcode:
Nonacoustic, radially propagating traveling waves have been observed in
the solar photosphere. These traveling waves have a period of 278 + or -
41 s. The vertical wavelength (approximately 500 km) and phase velocity
(approximately 2 km/s) of the waves are among their properties deduced
from the data. It is also observed that the waves have outgoing phase
part of the time and ingoing phase the remainder of the time. The
traveling waves are interpreted to be gravity waves. Their role in
the heating of the chromosphere is discussed.
---------------------------------------------------------
Title: Observation of Photospheric Gravity Waves
Authors: Stebbins, R. T.; Goode, P. R.; Hill, H. A.
1981BAAS...13..858S Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Vacuum Solar Telescope Alignment System
Authors: Dunn, R.; Spence, G.; Stebbins, R.; Hill, H.
1981siwn.conf..613D Altcode:
No abstract at ADS
---------------------------------------------------------
Title: A Antarctic Telescope
Authors: Stebbins, R.
1981siwn.conf..390S Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Extended Observations of Solar Oscillations
Authors: Stebbins, R. T.; Mann, R.
1981AnJUS..16..223S Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Observational tests of pulsation theory in the solar envelope
Authors: Stebbins, R. T.; Hill, H. A.; Zanoni, R.; Davis, R. E.
1980LNP...125..381S Altcode: 1980nnsp.work..381S
An improved observing technique has been used to look for long period
oscillations in the brightness of the extreme solar limb. This technique
provides a means for analyzing power spectra to secure a signature
characteristic of the signal's origin. Results show significant
improvement in the discrimination between solar oscillations, other
signals, and noise. Long period intensity oscillations can be seen at
the extreme solar limb.
---------------------------------------------------------
Title: Observations of long period oscillations in the solar limb
darkening function
Authors: Stebbins, R. T.
1980LNP...125..191S Altcode: 1980nnsp.work..191S
The FFTD (finite Fourier transform definition) method was extended by
simultaneous application of multiple edge definitions in a study of
long period solar oscillations. Results are presented as evidence of
the reality of long period brightness oscillations in the solar limb
darkening function.
---------------------------------------------------------
Title: Analysis of Pulsation Theory Tests in the Solar Envelope
Authors: Stebbins, R. T.
1979BAAS...11..398S Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Empirical tests of solar pulsation theory.
Authors: Stebbins, R. T.
1978BAAS...10..730S Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Long-period oscillations of the apparent solar diameter:
observations.
Authors: Brown, T. M.; Stebbins, R. T.; Hill, H. A.
1978ApJ...223..324B Altcode:
New observations of the time-varying component of the apparent solar
diameter are reported. Power spectra derived from these observations
reveal narrow-band oscillations at frequencies consistent with the
normal mode frequencies of a standard solar model. The amplitudes of
these oscillations are discussed and related to the observations of
other investigators. A detailed analysis of the experiment and its
associated sources of error is presented and used to show that there
is a very small likelihood that the power spectrum peaks are due to
nonsolar causes.
---------------------------------------------------------
Title: Observations of Long Period Solar Oscillations.
Authors: Stebbins, R.
1977BAAS....9R.568S Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Observed Oscillations of the Apparent Solar Diameter
Authors: Brown, T. M.; Stebbins, R. T.; Hill, H. A.
1976ssp..conf....1B Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Recent solar oblateness observations: data, interpretation,
and significance for earlier work.
Authors: Hill, H. A.; Stebbins, R. T.
1975NYASA.262..472H Altcode:
The paper compiles the evidence necessary for the interpretation
of an observed solar oblateness. Emphasis is on time-varying excess
brightness, intrinsic visual oblateness, and normal oscillation modes of
the sun. Solar edge definition is discussed, with particular attention
paid to the finite Fourier transform definition. The possible role of
solar oblateness in gravitation theory is considered.
---------------------------------------------------------
Title: The finite Fourier transform definition of an edge on the
solar disk.
Authors: Hill, H. A.; Stebbins, R. T.; Oleson, J. R.
1975ApJ...200..484H Altcode:
A technique for locating the edge of the sun is proposed. The technique
uses a finite Fourier transform of the observed limb-darkening function
to achieve reduced sensitivity to atmospheric and instrumental
effects and heightened sensitivity to the shape of the intrinsic
limb-darkening function. A theory is developed that predicts these
sensitivities. In order to facilitate wider application, general
relations are calculated. A testing program which complements the theory
is also reported. The location of the edge is shown to be influenced
only by solar phenomena down to the milli-arcsecond range.
---------------------------------------------------------
Title: The intrinsic visual oblateness of the sun.
Authors: Hill, H. A.; Stebbins, R. T.
1975ApJ...200..471H Altcode:
Solar oblateness observations are reported which yield a value of 18.4
plus or minus 12.5 milli-arcsec for the difference between equatorial
and polar diameters. These observations were conducted when the
time-varying excess equatorial brightness was markedly reduced, greatly
simplifying the interpretation of the apparent solar oblateness. The
experimental scheme for defining the 'edge' of the sun and monitoring
the shape of the extreme limb-darkening function is summarized along
with a description of the instrumentation. Sources of systematic error
are exhaustively surveyed to extract the intrinsic visual oblateness
of the sun. The result further strengthens the conclusion of Hill et
al. (1974) that the grave consequence of the Dicke-Goldenberg (1967)
work for Einstein's general theory of relativity is removed. This
result excludes an oblateness as large as that required by the rapidly
rotating interior models used to explain the low neutrino flux.
---------------------------------------------------------
Title: INVITED PAPER - Recent Progress in Solar Oblateness Studies
Authors: Hill, H. A.; Stebbins, R. T.; Brown, T. M.
1975BAAS....7R.478H Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Solar Oblateness, Excess Brightness, and Relativity.
Authors: Hill, H. A.; Clayton, P. D.; Patz, D. L.; Healy, A. W.;
Stebbins, R. T.; Oleson, J. R.; Zanoni, C. A.
1975PhRvL..34Q.296H Altcode:
No abstract at ADS
---------------------------------------------------------
Title: An observational investigation of the solar oblateness
Authors: Stebbins, Robin Tucker Tuck
1975PhDT.......304S Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Errata: "Solar oblateness, excess brightness, and relativity"
[Phys. Rev. Lett., Vol. 33, p. 1497 - 1500 (1974)].
Authors: Hill, H. A.; Clayton, P. D.; Patz, D. L.; Healy, A. W.;
Stebbins, R. T.; Oleson, J. R.; Zanoni, C. A.
1975PhRvL..34..296H Altcode:
No abstract at ADS
---------------------------------------------------------
Title: An Observational Investigation of the Solar Oblateness.
Authors: Stebbins, R. T.
1975PhDT.........8S Altcode:
In recent years, the sun's figure has come under close scrutiny
because it may reflect certain properties of the solar interior,
and because an aspherical solar mass would alter the interpretation
of a basic test of gravitation theories. A flurry of activity in this
area has been triggered by the 1967 report of an equatorial diameter
significantly larger than the polar diameter. A measurement of the
solar oblateness using different experimental techniques which finds
no comparable oblateness is reported. Further, the evidence indicates
an explanation for the disagreement between previous results. A number
of other interesting facets of the sun are also revealed.
---------------------------------------------------------
Title: Solar Oblateness, Excess Brightness, and Relativity
Authors: Hill, H. A.; Clayton, P. D.; Patz, D. L.; Healy, A. W.;
Stebbins, R. T.; Oleson, J. R.; Zanoni, C. A.
1974PhRvL..33.1497H Altcode:
New observations show a small difference between the sun's polar and
equatorial limb darkening functions. This excess equatorial brightness
varies in time and can be of sufficient magnitude to account for
the solar oblateness inferred by Dicke and Goldenberg from their
measurements. This removes the serious consequence of their work for
Einstein's general theory of relativity. The problems of a solar-edge
definition and the derivation of a solar mass quadrupole moment are
discussed.
---------------------------------------------------------
Title: Upper Limit on the Gravitational Flux Reaching the Earth from
the Crab Pulsar
Authors: Levine, Judah; Stebbins, Robin
1972PhRvD...6.1465L Altcode:
A 30-m laser interferometer has been used in a search for gravitational
radiation from the Crab pulsar. The minimum detectable signal would be
produced by an incident gravitational flux of 10<SUP>9</SUP> ergs/sec
cm<SUP>2</SUP> and we find no effect at this level.
