9,873 research outputs found
Fringe Science: Defringing CCD Images with Neon Lamp Flat Fields
Fringing in CCD images is troublesome from the aspect of photometric quality
and image flatness in the final reduced product. Additionally, defringing
during calibration requires the inefficient use of time during the night to
collect and produce a "supersky" fringe frame. The fringe pattern observed in a
CCD image for a given near-IR filter is dominated by small thickness variations
across the detector with a second order effect caused by the wavelength extent
of the emission lines within the bandpass which produce the interference
pattern. We show that essentially any set of emission lines which generally
match the wavelength coverage of the night sky emission lines within a bandpass
will produce an identical fringe pattern. We present an easy, inexpensive, and
efficient method which uses a neon lamp as a flat field source and produces
high S/N fringe frames to use for defringing an image during the calibration
process.Comment: accepted to PAS
Deterministic quantum state transfer of atoms in a random magnetic field
We propose a method for transferring atoms to a target quantum state for a
multilevel quantum system with sequentially increasing, but otherwise unknown,
energy splitting. This is achieved with a feedback algorithm that processes
off-resonant optical measurements of state populations during adiabatic rapid
passage in real-time. Specifically, we reliably perform the transfer
for a
sample of ultracold Rb in the presence of a random external magnetic
field
Supporting the active learning of collaborative database browsing techniques
We describe the implications of a study of database browsing behaviour for the development of a system to support more effective browsing. In particular we consider the importance of collaborative working, both in learning browsing skills and in co‐operating on a shared information‐retrieval task. From our study, we believe that an interface to support collaboration should promote the awareness of the activities of others, better visualization of the information data structures being browsed, and effective communication of the browsing process
Wind-tunnel/flight correlation study of aerodynamic characteristics of a large flexible supersonic cruise airplane (XB-701) 2: Extrapolation of wind-tunnel data to full-scale conditions
The results of calculations necessary to extrapolate performance data on an XB-70-1 wind tunnel model to full scale at Mach numbers from 0.76 to 2.53 are presented. The extrapolation was part of a joint program to evaluate performance prediction techniques for large flexible supersonic airplanes similar to a supersonic transport. The extrapolation procedure included: interpolation of the wind tunnel data at the specific conditions of the flight test points; determination of the drag increments to be applied to the wind tunnel data, such as spillage drag, boundary layer trip drag, and skin friction increments; and estimates of the drag items not represented on the wind tunnel model, such as bypass doors, roughness, protuberances, and leakage drag. In addition, estimates of the effects of flexibility of the airplane were determined
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