540. Detecting Point Sources in EUVE Survey Skymaps
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.
- 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.
[ EUVE Page]
Page adopted from CEA July 2000