540. Detecting Point Sources in EUVE Survey Skymaps (Lewis, 1993)

Abstract

A major focus of the Extreme Ultraviolet Explorer all-sky survey is the detection of new sources of extreme ultraviolet radiation. This paper describes the challenges involved in producing a catalog containing as many statistically significant detections as possible, with a small expected number of spurious detections.

Paper

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Figures

• Figure 1 (83kbyte image) : Left: EUVE skymap of the north ecliptic polar region in the Lexan bandpass. Several sources are visible. Center: Effective exposure time for the same field. Right: Count rate map obtained by dividing the raw counts in each pixel by the effective exposure. The residual artifacts are due to uncertainty in the vignetting maps used to calculate the effective exposure time.
• Figure 2 (34kbyte image) : Left: A 2 deg x 2 deg field surrounding a source detected in the Lexan skymap. Center: Simulated Poisson background map using the value of beta derived from an annulus around this source. Right: A simulated source generated with the maximum likelihood source intensity and position reported for this object, and superimposed on the Poisson background. The count rate is approximately 0.25 counts per second, with a Delta-C significance of 146 (or about 12 sigma). This detection is therefore very unlikely to be spurious; a catalog search revealed a magnitude 4.5 G8 star very close to the reported position.