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Дата изменения: Tue Aug 16 06:31:57 2005
Дата индексирования: Sat Dec 22 08:59:32 2007
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XMM-Newton Science Analysis System


omdetect (omdetect-5.0.7) [xmmsas_20050815_1803-6.5.0]

Meta Index / Home Page

SourceListFile

• COLUMN NO NAME UNITS DESCRIPTION
• 1 SRCNUM none

• 2 XPOS pixels x-coordinate of centroided source centre
• 3 YPOS pixels y-coordinate of centroided source centre
• 4 POSERR pixels error in x and y centroided position
• 5 RATE counts/sec Total measured source counts (after background subtraction) within default source extraction aperture (r=12 un-binned pixels), divided by exposure time.
• 6 RATE_ERR counts/sec
• 7 BACKGROUND_RATE counts/sec Total estimated background counts (scaled by area ratio, from the background annulus) within default source extraction aperture, divided by exposure time
• 8 SIGNIFICANCE none source counts / sqrt(source + background counts) (i.e. signal-to-noise ratio)
• 9 CORR_RATE counts/sec Background subtracted source count rate after extrapolating (if necessary) for the wings of the PSF where they extend beyond the default extraction aperture, and correcting for coincidence losses, time-degradation sensitivity and dead-time.
• 10 CORR_RATE_ERR counts/sec
• 11 CORR_BACKGROUND_RATE counts/sec BACKGROUND_RATE after correcting for coincidence losses.
• 12 PSF1_CORR percentage Point-spread function correction applied to extrapolate the RATE value from measurement aperture area to the default extraction area of 12 unbinned pixels
• 13 COINCLOSS_CORR percentage Coincidence-loss correction applied - (CORR_RATE - RATE) * 100.0 / RATE
• 14 NOPIXELS none Number of pixels contained by an extended source (EFLAG=1). Point-sources (EFLAG=1) will have this value set to zero.
• 15 APERTURE unbinned pixels For point sources (EFLAG=0), the aperture radius (unbinned pixels) used in the photometry. For extended-sources (EFLAG=1) this value will be set to NULL.
• 16 FWHM_MAJ arcsecs The full-width-at-half-maximum of the semi-major axis of the ellipse describing the shape of the source (computed by moments)
• 17 FWHM_MIN arcsecs The full-width-at-half-maximum of the semi-minor axis of the ellipse describing the shape of the source (computed by moments)
• 18 PA degrees The postion-angle (measured counterclockwise from the x-axis) of the semi-major axis of the ellipse describing the shape of the source (computed from moments)
• 19 QFLAG none Source quality flag - Please see below
• 20 CFLAG none Source confusion flag - Please see below
• 21 EFLAG none (source extension flag) Either 0 point-source (none-extended) or 1 extended.

  Quality flag settings

• Bit set, integer value, reason
• 0, 1, Source lies above one or more bad pixels
• 1, 2, Source may be affected by a read-out streak
• 2, 4, Source may be affected by a smoke-ring
• 3, 8, Source may be affected by a star diffraction spike
• 4, 16, Very bright source with a strong modula 8 pattern
• 5, 32, Source lies within central enhanced region

  For example, a source with a bad pixel and lying on or close to a read-out streak would have bits 0 and 1 set and thus have a quality flag value of 3.

  Confusion flag settings

• Bit set, integer value, reason
• 0, 1, Point source has one or more sources within a radius of 6-12 unbinned pixels
• 1, 2, Point source has one or more sources within a radius of 3-6 unbinned pixels
• 2, 4, Source lies near to an edge of the image
• 3, 16, Source lies near to a bright source
• 4, 32, Point source lies partly or totally within an extended region

  For example, a source lying near to an image edge and having a neighbour at a distance of 10 unbinned pixels would have bits 2 and 1 set and would thus have a confusion flag value of 5.