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 |
| POSERR | FLOAT | pixels | error in x and y centroided position |
| RA | DOUBLE | degrees | RA (J2000) mosaiced sky-images only |
| DEC | DOUBLE | degrees | DEC (J2000) mosaiced sky-images only |
| RA_CORR | DOUBLE | degrees | RA (J2000) corrected for the boresight offset |
| DEC_CORR | DOUBLE | degrees | DEC (J2000) corrected for the boresight offset |
| LII | DOUBLE | degrees | Galactic longitude |
| BII | DOUBLE | degrees | Galactic lattitude |
| 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 + background counts) i.e. signal-to-noise ratio, where the counts refer to the r̈awc̈ounts, 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 the measurement aperture area to the default extraction area of 12 unbinned pixels |
| PSF2_CORR | FLOAT | % | Point-spread function correction applied to extrapolate the RATE value from the extraction area of 12 unbinned pixels to the CAL (photometric) radius |
| SPB_COILOSS | FLOAT | % | Coincidence-loss correction applied to the source plus background rate (ratio of the coincidence-loss corrected source + coincincidence-loss corrected background count-rate to the raw source + raw background count-rate) |
| BK_COILOSS | FLOAT | % | Coincidence-loss correction applied to the raw-background rate (ratio of the coincidence-loss corrected background count-rate to the raw background count-rate) |
| MAG | FLOAT | mag | Instrumental magnitude |
| MAGERR | FLOAT | mag | Instrumental magnitude error |
| 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. |
| SRC_ID | INT 32 | none | Source ID number in the source-list file |
