1,272 research outputs found
The Generalized Spectral Kurtosis Estimator
Due to its conceptual simplicity and its proven effectiveness in real-time
detection and removal of radio frequency interference (RFI) from radio
astronomy data, the Spectral Kurtosis (SK) estimator is likely to become a
standard tool of a new generation of radio telescopes. However, the SK
estimator in its original form must be developed from instantaneous power
spectral density (PSD) estimates, and hence cannot be employed as an RFI
excision tool downstream of the data pipeline in existing instruments where any
time averaging is performed. In this letter, we develop a generalized estimator
with wider applicability for both instantaneous and averaged spectral data,
which extends its practical use to a much larger pool of radio instruments.Comment: 5 pages, 2 figures, MNRAS Letters accepte
Tau contribution and precision measurement of theta23 at a neutrino factory
We discuss precision measurements of the leading atmospheric parameters at a
standard neutrino factory. The oscillation of the muon and electron neutrinos
(anti-neutrinos) to tau neutrinos (anti-neutrinos) adds to the muon events
sample (both right sign and wrong sign) via leptonic decays of the taus
produced through charge-current interactions in the detector. We focus on how
this contribution affects a precision measurement of the atmospheric mixing
parameters and the deviation of muon neutrino -- tau neutrino mixing from
maximality.Comment: 4 pages, 5 figures, presented by NS at the 11th International
Workshop on Neutrino Factories, Superbeams and Beta Beams (Nufact09), July
20-25, 2009, Illinois Institute of Technology, Chicago, US
Note on Invariants of the Weyl Tensor
Algebraically special gravitational fields are described using algebraic and
differential invariants of the Weyl tensor. A type III invariant is also given
and calculated for Robinson-Trautman spaces.Comment: 3 pages, no figures, corrected expression (12
New Interactive Solar Flare Modeling and Advanced Radio Diagnostics Tools
The coming years will see routine use of solar data of unprecedented spatial
and spectral resolution, time cadence, and completeness in the wavelength
domain. To capitalize on the soon to be available radio facilities such as the
expanded OVSA, SSRT and FASR, and the challenges they present in the
visualization and synthesis of the multi-frequency datasets, we propose that
realistic, sophisticated 3D active region and flare modeling is timely now and
will be a forefront of coronal studies over the coming years. Here we summarize
our 3D modeling efforts, aimed at forward fitting of imaging spectroscopy data,
and describe currently available 3D modeling tools. We also discuss plans for
future generalization of our modeling tools.Comment: 4 pages; IAU Symposium # 274 "Advances in Plasma Astrophysics"; typo
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