Background and Objectives: For total analytical error, imprecision (SD) and bias, performance goals for laboratory tests have most often been developed. A total analytical error goal requires that the combination of errors from all sources (random and systematic errors) be within some acceptable limit. M...

background and objectives: for total analytical error, imprecision (sd) and bias, performance goals for laboratory tests have most often been developed. a total analytical error goal requires that the combination of errors from all sources (random and systematic errors) be within some acceptable limit. materials and methods: fifty vials of sodium and potassium standards (sandos company) were ch...

High-precision fast photometry from ground-based observatories is a challenge due to intensity fluctuations (scintillation) produced by the Earth’s atmosphere. Here we describe a method to reduce the effects of scintillation by a combination of pupil reconjugation and calibration using a comparison star. Because scintillation is produced by high-altitude turbulence, the range of angles over whi...

The aperture photometry package ‘vaphot’ was developed to perform reliable and precise time-series photometry of uncrowded fields. This package works within the IRAF environment and is built upon the standard aperture photometry task ‘phot’ from IRAF. The design goal of ‘vaphot’ was a simple-to-use photometry task with relatively few input parameters that performs precise aperture photometry, u...

A summary of the photometric data obtained by the Hipparcos and Tycho missions is presented. The photometric signals and their reduction to magnitudes are described, as well as the passbands and their evolution. The main mission photometry provided on average 110 observations for each of the 118 000 stars observed during the mission. The accuracies for this epoch photometry range from a few mil...

A uni® ed system of photometry is proposed that is based on human vision and allows the speci® cation of visual stimuli at all light levels. To be useful, however, photometry can never be entirely synonymous with vision. Additivity is an essential characteristic of photometry, yet many visual responses, such as brightness matching, incorporate visual channels that are inherently non-additive in...