XMM-Newton Science Analysis System


omdetect (omdetect-5.19.4) [xmmsas_20090615_1801-9.0.0]

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Output source-list file

The source-list file produced by omdetect contains a list of the positions of all the detected sources, the parameterizations of their shapes, their extracted count-rates, and "corrected count-rates" which contain some of the corrections that are needed to convert the raw rates to the rates that can be used to compute instrumental magnitutes. Fully corrected count-rates and instrumental magnitudes are obtained by running ommag, with its parameter ``set'' set to the omdetect source-list.

The source-list file is in FITS file format and contains a SRCLIST table with the columns shown in the following table.

COLUMN NAME	KIND	UNITS	DESCRIPTION
SRCNUM	INT 32	none	Source number - order of detection
XPOS	FLOAT	pixels	x-coordinate of centroided source centre
YPOS	FLOAT	pixels	y-coordinate of centroided source centre
RA	DOUBLE	degrees	RA (J2000) mosaiced sky-images only
DEC	DOUBLE	degrees	DEC (J2000) mosaiced sky-images only
POSERR	FLOAT	pixels	error in x and y centroided position
RATE	FLOAT	counts/sec	Total measured source count-rate (after background subtraction) within source extraction aperture (default aperture=12 un-binned pixels, but a smaller one may have been used), divided by exposure time.
RATE_ERR	FLOAT	counts/sec	Error in the raw count-rate
BACKGROUND_RATE	FLOAT	counts/sec	Total estimated background count-rate (scaled by area ratio, from the background annulus) within default source extraction aperture, divided by exposure time
SIGNIFICANCE	FLOAT	none	source counts / sqrt(source + 2 $\times$ background counts) (i.e. signal-to-noise ratio), where the counts refer to the rawcounts, before any corrections have been applied.
CORR_RATE	FLOAT	counts/sec	Background subtracted source count rate after applying PSF (if necessary) and coincidence-loss corrections.
CORR_RATE_ERR	FLOAT	counts/sec	Error in the corrected rate
CORR_BACKGROUND _RATE	FLOAT	counts/sec	BACKGROUND_RATE after correcting for coincidence losses.
PSF1_CORR	FLOAT	%	Point-spread function correction applied to extrapolate the RATE value from measurement aperture area to the default extraction area of 12 unbinned pixels
SPB_COILOSS	FLOAT	%	Coincidence-loss correction applied to the source plus background rate (100 $\times$ coincidence-loss corrected total count-rate/raw total count-rate)
BK_COILOSS	FLOAT	%	Coincidence-loss correction applied to the raw-background rate (100 $\times$ coincidence-loss corrected background count-rate/raw background count-rate)
NOPIXELS	INT 32	none	Number of pixels contained by an extended source (EFLAG=1). Point-sources (EFLAG=0) will have this value set to zero.
APERTURE	FLOAT	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.

COLUMN NAME	KIND	UNITS	DESCRIPTION
FWHM_MAJ	FLOAT	arcsecs	The full-width-at-half-maximum of the semi-major axis of the ellipse describing the shape of the source (computed by moments - Set to NULL if a reliable value couldn't be computed.)
FWHM_MAJ_ERR	FLOAT	pixels	The computed error of the major-axis
FWHM_MIN	FLOAT	pixels	The full-width-at-half-maximum of the semi-minor axis of the ellipse describing the shape of the source (computed by moments - Set to NULL if a reliable value couldn't be computed.)
FWHM_MIN_ERR	FLOAT	arcsecs	The computed error of the minor-axis
PA	FLOAT	degrees	The position-angle (measured anti-clockwise from the positive x-axis) of the semi-major axis of the ellipse describing the shape of the source (computed from moments - Set to NULL if a reliable value couldn't be computed.)
PA_ERR	FLOAT	degrees	The computed error of the position angle
QFLAG	INT 16	none	Source quality flag - Please see below
CFLAG	INT 8	none	Source confusion flag - Please see below
EFLAG	INT 8	none	(source extension flag) Either 0 point-source (non-extended) or 1 extended.