Changes between Version 4 and Version 5 of psphotStack

Timestamp:

Jun 13, 2012, 3:05:37 PM (14 years ago)

Author:

eugene

Comment:

--

psphotStack

@@ -24 +24 @@
 || 10 || 112.80 || 176.88 || 28.20 || 44.22 ||
 
-These have been chosen to match the apertures defined by SDSS (see [http://www.sdss.org/dr7/algorithms/photometry.html#photo_profile photo profile]).
+These have been chosen to match the apertures defined by SDSS (see [http://www.sdss.org/dr7/algorithms/photometry.html#photo_profile photo profile]).  For any given `psphotStack` analysis, the radial apertures actually used are written to the header of the corresponding XRAD extension (see keywords RMIN_NN and RMAX_NN).  
+
+Note: `psphotStack` calculates the total flux within each circular aperture (not the annulus).  The following values are saved in the smf/cmf file in the `XRAD` extension:
+
+|| field || contents ||
+|| IPP_IDET || unique (within this skycell) detection ID; matches the detection ID for the corresponding PSF entry in the `PSF` extension ||
+|| X_APER || center of the aperture in pixels (same as the centroid or the peak) ||
+|| Y_APER || center of the aperture in pixels (same as the centroid or the peak) ||
+|| PSF_FWHM || fwhm of the matched psf (in pixels) or NaN if NOT matched ||
+|| APER_FLUX || sum of counts within the aperture ||
+|| APER_FLUX_ERR || formal error on the flux (sqrt(sum(variance)) ||
+|| APER_FLUX_STDEV || standard deviation of flux (in fact standard deviation of the per-pixel surface brightness) ||
+|| APER_FILL || fraction of the circular aperture filled with pixels (number of unmasked pixels / Area in pixels -- note this can be > 1 due to boundary differences) ||
+
+The APER_* fields are written as FITS vectors with multiple elements per field corresponding to each of the radial apertures defined above.
+
+If an object listed in the PSF table has radial aperture photometry measured, then that object will have multiple rows in the XRAD table, one for each of the PSF values: raw, matched version 1, matched version 2, etc.  
+
+the centroid is used if:
+* the object is saturate
+* the moments are defined and measured
+* the centroid does not deviate from the peak position by more than 1.5 pixels, unless saturated
+otherwise, the peak position is used.
+
+