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Dr.  Daniel Lebach
Harvard-Smithsonian Center for Astrophysics
Seeing spots: a report on optical and very-long-baseline radio interferometry
observations of IM Pegasi, the guide star for the Gravity Probe B mission. ”
  The NASA/Stanford Gravity Probe B (GP-B) mission is designed to measure two effects predicted by general relativity that result in the steady drift in orientation of the spin axes of four gyroscopes housed in a spacecraft in a drag-free, low-Earth polar orbit.  The changes in direction of the spin axes of the gyroscopes over time is measured relative to the direction to the binary star IM Pegasi (HR 8703).  To measure the relativistic drifts accurately, any changes in the apparent position of the star relative to an inertial (i.e., extragalactic) frame must be accounted for.  In particular, any error in the assumed proper motion of the star will map directly into the estimated relativistic drift rates.  I will present results from multiple types of optical observations of IM Peg that were intended to measure or provide upper bounds on particular contributions to the apparent motion of the star as seen by the spacecraft's on-board star-tracking telescope.  I will then focus on our very-long-baseline radio interferometry (VLBI) observations of IM Peg, which we used to measure the proper motion of the star with an accuracy goal of 0.14 milliarcseconds/yr (standard error) in both the "north-south" and "east-west" directions relative to an extragalactic frame.

Location: Applied Physics 200, AP200
Wednesday, May 9, 2007, 4:00 – 5:30 pm
Light refreshments available 4pm; Presentation begins 4:15pm. Open to all.

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Previous HEPL Seminars 2004, 2005, 2006, 2007, 2008:

Dr. Stefan Funk
Assistant Professor, Physics, Stanford University and SLAC
“Gamma-ray astronomy: Status and Future Directions”
Wednesday, January 30, 2008

Dr. Joerg Wagner
University of Stuttgart
“The Origin of the Modern Gyroscope: Bohnenberger's Machine and the Scientific Work of its Inventor”
January 16, 2008

Professor Bob Bingham
Rutherford Appleton Laboratory
“Probing Quantum Gravity Using Matter”
Wednesday, December 12, 2007

Richard N. Boyd
Science Director, National Ignition Facility
Lawrence Livermore National Laboratory
“Creating a Star in the Laboratory: the National Ignition Facility”
Wednesday, November 28, 2007

Domenico Gerardi
Visiting researcher, Hansen Experimental Physics Laboratory, Stanford University
PhD candidate, University of Stuttgart and Science Missions & Systems EADS Astrium
“Achieving disturbance reduction for future drag-free missions. ”
Wednesday, October 24, 2007

Fabio Scardigli
Department of Physics, University of Milano, Italy
"The Equivalence Principle, the Uncertainty Principle and Some Fundamental Physics Questions"
Wednesday, May 23, 2007

Dr. Gregory P. Crawford, Dean of Engineering and Professor of Engineering & Physics
Brown University, Division of Engineering
In Vivo Spectroscopy for Blood Analyte Monitoring
Wednesday, April 25, 2007

Professor C.W. Francis Everitt
W.W. Hansen Experimental Physics Laboratory, Stanford University
“Maxwell at 175 ”
Wednesday, March 14, 2007

Paul Brink
Department of Physics, Stanford University speaking for the (Super)CDMS collaboration
“Present status and future plans of the Cryogenic Dark Matter Search (CDMS)”
Wednesday, February 28, 2007

Alfred Vogel
Institute of Biomedical Optics University of Lübeck, Germany
“New findings on plasma and cavity generation in aqueous media with fs and ns laser pulses, and their applications in cell surgery"
Thursday, January 25, 2007

Dr. Dan McCleese
Chief Scientist, Jet Propulsion Laboratory
“Recent Results and Future Direction of the Exploration of Mars"
Tuesday, September 26, 2006

Ned Wright
Professor of Physics and Astronomy, UCLA
What's New in Cosmology?

Thursday 9 March 2006

Peter Michelson
Stanford University
GLAST: The Gamma-ray Large Area Space Telescope Mission
Seminar and Tour

Thursday 16 Feb 2006

Robert L. Byer
Stanford University
"Acceleration of Electrons with Visible Light"

Wednesday 1 Feb 2006

Emeline Guiu
Office National d’Etudes et de Recherches Aérospatiales (ONERA)
The MICROSCOPE Mission and In-Flight Calibration
Emeline Guiu, Danya Hudson

Wed 7 Dec 2005

Dr. Nicholas White
Chief, Laboratory for High Astrophysics NASA Goddard Space Flight Center
“The NASA Beyond Einstein Program”

Wed 5 Oct 2005

Ulrich Schreiber, Forschungseinrichtung Satellitengeodäsie, TU-München
“High Precision Sagnac Interferometry for Applications in Geoscience ”
Thursday, September 8, 2005

Christopher D. Bass, Indiana University / IUCF, “Measurement of the Parity-Odd Neutron Spin Rotation in Liquid-4He”
Monday, August 22, 2005

Anne Kinney, Director, Universe Division in the Science Mission Directorate, NASA, "Blue Planets, Black Holes"
Wednesday, 20 July 2005

Dr William Tobin, Department of Physics & Astronomy, University of Canterbury, New Zealand, "Foucault's Gyroscope of 1852"
Friday, 8 April 2005

Rex Geveden, NASA Chief Engineer, Independent Technical Authority
7 April 2005

Shooting the Moon: Probing Fundamental Gravity in the Solar System
Tom Murphy, UC San Diego 3 March 2005

The GRACE Mission: Status and Science Results John Ries, Senior Research Scientist at the Center for Space Research at The University of Texas at Austin, 14 February 2005.

Hubble Robotic Servicing - Recent Engineering Development, Bill Reeve
Civil Space Director of Advanced Science Programs, Lockheed Martin, 26 January 2005.

Interferometry for LISA, Daniel Shaddock, PhD, Interferometry Metrology and Optics Group, Jet Propulsion Laboratory, 17 November 2004.

The Large Synoptic Survey Telescope (LSST), Steve Kahn, Deputy Director, Kavli Institute for Particle Astrophysics and Cosmology, 27 October 2004.

HEPL-KIPAC Showcase. 29 September 2004. Agenda