Poor knowledge of or means of measuring the effective wavelength of operation led to uncertainty in the spatial frequency assigned to observations whose visibilities had been measured with higher precision.Non-uniformities in the piezo scanning rate are another example of an avoidable hardware fault.Tags: Business Planning Process MapMortgage Business PlanEasy Essay On Quaid E Azam In UrduThesis For MusicCreative Writing Courses CambridgeCollection Data ThesisChicago Manual Of Style Research PaperA Level Ict Coursework HelpPersonal Accomplishment Essay
Direct detection of exoplanets using long-baseline interferometry and visibility phase J. Le Poole View Abstract Proceedings SPIE v8445 Optical and Infrared Interferometry II, SPIE conference, Amsterdam, July 2012 The polarization-based collimated beam combiner and the proposed NOVA fringe tracker (NFT) for the VLTI Jeffrey A. SPIE 4006, pp 1068, Astronomical Interferometry, Proceedings of the conference "Interferometry in Optical Astronomy," held March 26 - 29, 2000, Munich, Germany Use of a Seeing Monitor to Determine the Velocities of Turbulent Atmospheric Layers Richard Roosen, Jeffrey Meisner View Abstract Working on the Fringe: Optical and IR Interferometry from Ground and Space. This refers to imbalance in the beam combiner which results in fluctuations of the incoming wavefronts and the proportion of power accepted by a spatial filter masquerading as a visibility, a common problem afflicting previous interferometric instruments and fringe trackers.
Meisner Presentation made in Leiden 27 June 2003 based on a poster presented at XIXth IAP Colloquium "Extrasolar Planets : Today and Tomorrow" held in Paris, 30 June - 4 July 2003 View Abstract The NOVA Fringe Tracker: a second generation cophasing facility for up to six telescopes at the VLTI Jeffrey A. Also proposed for use in science instruments (for the measurement of visibility), the Polarization-Based Collimated Beam Combiner, with its achievement of photometric symmetry in hardware, is particularly suited for combined use of the smaller AT (1.8 meter) telescopes with the UT (8 meter) telescopes involving a 20:1 intensity ratio of the interfering beams, and also for fringe tracking using highly resolved sources having a very small visibility.
155 stars were observed sufficiently to consider, some of which are rather dim or might not be properly fit using a UD visibility function.
The better half of this set, 77 stars, all had a median residual which was better than 1.2% of the visibility itself.
Aiming for an instrument achieving the best limiting sensitivity, analysis and simulations predict that reliable cophasing will be obtained using the 1.8 meter AT telescopes tracking on an unresolved reference star with a K magnitude of 10 VINCI: The first interferometric instrument at the VLTI, its success story, and technical lessons learned Jeff Meisner ABSTRACT VINCI was the first interferometric instrument implemented at the VLTI, intended primarily as a test and alignment instrument, but which delivered scientific results far exceeding any initial expectations.
A very brief overview of the instrument and its operational history is presented.For instance, the long scans used in normal observing modes meant that the instrument spent 90% of the time completely off-fringe, leading to this observing inefficiency.The ultimate test of the instrument's precision can be inferred from fitting calibrated visibilities obtained to the UD visibility function and analyzing the residuals obtained.19 stars had a median residual better than .7% of the measured visibility.Some parameters of the hardware were insufficiently characterized, controlled, and/or monitored.The present work tries to improve experimental sensitivity to the oscillation parameters by considering neutrino events which are discarded by the previous analysis - escaping events.The biggest issues with the escaping sample are significant cosmic background and correct energy estimation.Such limitations only became issues once VINCI was employed for generating scientific results that went well beyond its initial design as a test and alignment instrument. Pereira, Andreas Quirrenbach, David Raban, Amir Vosteen ABSTRACT The Polarization-Based Collimated Beam Combiner efficiently produces pairwise interference between beams from multiple telescopes.From these shortcomings in an otherwise exemplary instrument, some obvious lessons can be learned. An important feature is achieving "Photometric Symmetry" whereby interference measurements have no first-order sensitivity to wavefront perturbations (or photometric variations following spatial filtering) which otherwise entail visibility measurements with increased error, bias, and nonlinearity in phase determination.The talk will then concentrate on some technical issues affecting the instrument, both positive and negative, and some lessons that can be learned.These issues are illustrated in each case using results obtained from analysis of on-sky (and some technical) data sets.