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Forced Photometry refers to photometric measurements conducted at a prespecified location.  Forced photometry measurements are usually made in aperture photometry mode (is that correct?).

 

Contents

Forced Photometry at Object Locations

 

Parameters in database

Several tables contain information relevant to Forced Photometry:

  • ForcedWarpMeasurement: Contains single epoch forced photometry of individual measurements of objects detected in the stacked images. The identifiers connecting the measurement back to the original image and to the object association are provided. PSF, aperture, and Kron (1980) photometry are included, along with sky and detector coordinate positions. References: Kron, R. G. 1980, ApJS, 43, 305.
  • ForcedWarpExtended: Contains the single epoch forced photometry fluxes within the SDSS R5 (r = 3.00 arcsec), R6 (r = 4.63 arcsec), and R7 (r = 7.43 arcsec) apertures (Stoughton 2002) for objects detected in the stacked images. References: Stoughton, C., Lupton, R. H., Bernardi, M., et al. 2002, AJ, 123, 485.
  • ForcedWarpLensing: Contains the Kaiser et al. (1995) lensing parameters measured from the forced photometry of objects detected in stacked images on the individual single epoch data. References: Kaiser, N., Squires, G., and Broadhurst, T. 1995, ApJ, 449, 460.
  • ForcedMeanObject: Contains the mean of single-epoch photometric information for sources detected in the stacked data, calculated as described in Magnier et al. (2013). The mean is calculated for detections associated into objects within a one arcsecond correlation radius. PSF, Kron (1980), and SDSS aperture R5 (r = 3.00 arcsec), R6 (r = 4.63 arcsec), and R7 (r = 7.43 arcsec) apertures (Stoughton 2002) magnitudes and statistics are listed for all filters. References: Kaiser, N., Squires, G., and Broadhurst, T. 1995, ApJ, 449, 460; Kron, R. G. 1980, ApJS, 43, 305; Magnier, E. A., Schlafly, E., Finkbeiner, D., et al. 2013, ApJS, 205, 20; Stoughton, C., Lupton, R. H., Bernardi, M., et al. 2002, AJ, 123, 485.
  • ForcedMeanLensing: Contains the mean Kaiser et al. (1995) lensing parameters measured from the forced photometry of objects detected in stacked images on the individual single epoch data. References: Kaiser, N., Squires, G., and Broadhurst, T. 1995, ApJ, 449, 460.
  • ForcedGalaxyShape: Contains the extended source galaxy shape parameters. All filters are matched into a single row. The positions, magnitudes, fluxes, and Sersic indices are inherited from their parent measurement in the StackModelFit tables, and are reproduced here for convenience. The major and minor axes and orientation are recalculated on a warp-by-warp basis from the best fit given these inherited properties. References: Sersic, J. L. 1963, Boletin de la Asociacion Argentina de Astronomia La Plata Argentina, 6, 41.
  • ForcedWarpMasked: Contains an entry for objects detected in the stacked images which were in the footprint of a single epoch exposure, but for which there are no unmasked pixels at that epoch.

The specific contents of each Table can be obtained from the linked pages.

Need to recommend Table with most useful photometric parameters.  Some tables focus on shape measurements, which are critical for lensing work but not relevant for other projects.

 

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