A Simple BATSE Measure of GRB Duty Cycle

We introduce a definition of gamma-ray burst (GRB) duty cycle that describes the GRB's efficiency as an emitter; it is the GRB's average flux relative to the peak flux. This GRB duty cycle is easily described in terms of measured BATSE parameters; it is essentially fluence divided by the quantity peak flux times duration. Since fluence and duration are two of the three defining characteristics of the GRB classes identified by statistical clustering techniques (the other is spectral hardness), duty cycle is a potentially valuable probe for studying properties of these classes.Comment: 4 pages, 1 figure, presented at the 5th Huntsville Gamma-Ray Burst Symposiu

Patterns of Employee Particpation and Industrial Democracy in UK ESOPs

This paper examines the institutional characteristics of UK ESOPs and considers the extent to which ESOPs extend employee participation and industrial democracy. It is suggested that ESOPs in themselves do not extend industrial democracy. Instead patterns of employee participation are substantially determined by the goals of those primarily responsible for establishing the ESOP. Three constellations of ESOPs are discerned on the basis of their participative characteristics: `technical ESOPs' where there is little or no development of industrial democracy; `paternalist ESOPs' which tend to develop individualistic forms of employee participation; and `representative ESOPs' where new institutions are created to give some opportunity for involvement of employee representatives in top decisions.

Time Dependent Clustering Analysis of the Second BATSE Gamma-Ray Burst Catalog

A time dependent two-point correlation-function analysis of the BATSE 2B catalog finds no evidence of burst repetition. As part of this analysis, we discuss the effects of sky exposure on the observability of burst repetition and present the equation describing the signature of burst repetition in the data. For a model of all burst repetition from a source occurring in less than five days we derive upper limits on the number of bursts in the catalog from repeaters and model-dependent upper limits on the fraction of burst sources that produce multiple outbursts.Comment: To appear in the Astrophysical Journal Letters, uuencoded compressed PostScript, 11 pages with 4 embedded figure

AI Gamma-Ray Burst Classification: Methodology/Preliminary Results

Artificial intelligence (AI) classifiers can be used to classify unknowns, refine existing classification parameters, and identify/screen out ineffectual parameters. We present an AI methodology for classifying new gamma-ray bursts, along with some preliminary results.Comment: 5 pages, 2 postscript figures. To appear in the Fourth Huntsville Gamma-Ray Burst Symposiu

The BATSE Gamma-Ray Burst Spectral Catalog. I. High Time Resolution Spectroscopy of Bright Bursts using High Energy Resolution Data

This is the first in a series of gamma-ray burst spectroscopy catalogs from the Burst And Transient Source Experiment (BATSE) on the Compton Gamma Ray Observatory, each covering a different aspect of burst phenomenology. In this paper, we present time-sequences of spectral fit parameters for 156 bursts selected for either their high peak flux or fluence. All bursts have at least eight spectra in excess of 45 sigma above background and span burst durations from 1.66 to 278 s. Individual spectral accumulations are typically 128 ms long at the peak of the brightest events, but can be as short as 16 ms, depending on the type of data selected. We have used mostly high energy resolution data from the Large Area Detectors, covering an energy range of typically 28 - 1800 keV. The spectral model chosen is from a small empirically-determined set of functions, such as the well-known `GRB' function, that best fits the time-averaged burst spectra. Thus, there are generally three spectral shape parameters available for each of the 5500 total spectra: a low-energy power-law index, a characteristic break energy and possibly a high-energy power-law index. We present the distributions of the observed sets of these parameters and comment on their implications. The complete set of data that accompanies this paper is necessarily large, and thus is archived electronically at: http://www.journals.uchicago.edu/ApJ/journal/.Comment: Accepted for publication: ApJS, 125. 38 pages, 9 figures; supplementary electronic archive to be published by ApJ; available from lead author upon reques

BATSE Sky Exposure

Angular sky exposure is presented for a number of published BATSE gamma-ray burst catalogs. A new algorithm was required due to telemetry gaps resulting from onboard tape recorder failures; the new algorithm improves the 1B Catalog exposure calculation. The most influential effects limiting BATSE's exposure are (1) deadtime due to triggering, (2) sky blockage by the Earth, and (3) trigger disabling when the spacecraft is in the SAA and over other specific Earth locations. Exposure has improved during the CGRO mission as a result of decreased Solar flares and magnetospheric particle events.Comment: 5 pages, 1 postscript figure. To appear in the Fourth Huntsville Gamma-Ray Burst Symposiu

BATSE Gamma-Ray Burst Line Search: V. Probability of Detecting a Line in a Burst

The physical importance of the apparent discrepancy between the detections by pre-BATSE missions of absorption lines in gamma-ray burst spectra and the absence of a BATSE line detection necessitates a statistical analysis of this discrepancy. This analysis requires a calculation of the probability that a line, if present, will be detected in a given burst. However, the connection between the detectability of a line in a spectrum and in a burst requires a model for the occurrence of a line within a burst. We have developed the necessary weighting for the line detection probability for each spectrum spanning the burst. The resulting calculations require a description of each spectrum in the BATSE database. With these tools we identify the bursts in which lines are most likely to be detected. Also, by assuming a small frequency with which lines occur, we calculate the approximate number of BATSE bursts in which lines of various types could be detected. Lines similar to the Ginga detections can be detected in relatively few BATSE bursts; for example, in only ~20 bursts are lines similar to the GB 880205 pair of lines detectable. Ginga reported lines at ~20 and ~40 keV whereas the low energy cutoff of the BATSE spectra is typically above 20 keV; hence BATSE's sensitivity to lines is less than that of Ginga below 40 keV, and greater above. Therefore the probability that the GB 880205 lines would be detected in a Ginga burst rather than a BATSE burst is ~0.2. Finally, we adopted a more appropriate test of the significance of a line feature.Comment: 20 pages, AASTeX 4.0, 5 figures, Ap.J. in pres