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2MASS Final Release Validation Page

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The page summarizes the validation tasks being performed on the final release catalog datasets for 2MASS. The aims of this process are to

• ensure that the distributed results are globally consistent with the project's Level 1 specifications and expectations of overall quality and uniformity.
• inspect the dataset for local significant violations of specifications which may not appear in global analyses
• track the efficacy of corrections applied to the data
• provide characterization of the release datasets to aid users analyses via explanatory material.

This placeholder list is meant to stimulate discussion to
flesh out a comprehensive inventory of analysis tasks.  It
will evolve and be updated as the availability of the 
full databases approaches.

For the purposes of discussion on 9/10/2002 we should consider
to what extent some these tests have already been evaluated on
working/evolving catalog.


1. Sky Coverage

   - Effective coverage for Images, PSC, XSC -- where are the holes? Cambresy
        -- Does sum of sources per scan used equal total draw?
        -- Does the distribution of release sources reflect the
             tile boundaries
        -- Do "A" sources have the same spatial distribution as the
            tile boundaries
   - Effect of Bright Stars and Large Galaxies
        -- Compile total area "lost" to bright stars (will depend
          on flagging -- star blanking areas are not "opaque") Tam
        -- Stack many different bright stars and plot nearby points
        Evans,Tam
        -- Empirically evaluate the performance of MAPCOR Stiening
   
2. Sensitivity, Completeness and Reliability  (Level 1 Specifications)

   -- Atmospheric Effects (PSP+zero point maps) Cutri,Cambresy
   -- Source Density/Confusion Effects (Point and Extended Source count slope
        and roll-over maps, mean color distributions)  Carpenter
   -- System Effects (telescope, camera, software)
           effects of J-band zeropoint variation, array change,
           primary mirror washing, recollimation, image elongation.
   Skrutskie
   -- Calibration scan repeatability analysis --
   Completeness/reliability Skrutskie

3. Astrometry

   - Independent confirmation by Zacharias
   - Mean accuracy with respect to Tycho 2 and other large scale
        external catalogs, such as UCAC, FIRST (for extended sources) McCallon,Jarrett
   - Internal consistency (scan overlaps) Wheelock
   - Large-scale trends (cross-scan position, pole dependencies) McCallon
   - Characterization of astrometric uncertainties McCallon

4. Photometry (PSC and XSC)

   - Internal Consistency (repeatability, overlaps) Wheelock
   - Uniformity (mean colors, CMDs, color maps, star-counts rollover,
          -- evaluate for regions of different spatial dimension
             (great circles, declination bands...) Weinberg
          -- Fundamental question:  How to tune selection to remove 
              survey scan pattern systematics  Skrutskie
    - Large-scale trends 
        cross-scan, confusion, seeing shape dependence,
	background/zeropoint dependence  Skrutskie
        -- Look at histogram of prox vs. seeing Stiening
   - Nature and origin of sources with obviously wrong colors 
         -- exploit new image servers Skrutskie
         -- tchester looks at xsc Chester
   - Statistics of SNR's and _msigs
         -- global validation of cmsig (range check) Marsh,Tam
         -- range check msigcom Tam
   - Characterization of aperture photometry vs. PSF photometery
         -- develop rules for user to favor aperture over psf Liebert
   - Photometric characteristics vs. proximity Skrutskie
   - Characterization of the photometric quality flag. Skrutskie
         -- outline rationale for flagging and suggested uses
   - Comparison with 2nd Incremental release 
         -- join catalogs look for expected and unexpected deltas Stiening?
 

5. Photometric System and Calibration

   - Calibration uniformity/stability (photometry of standards in PSC) Cutri
   - System transformations Carpenter
   - Absolute Calibration Cutri (via Cohen)
   - North vs. South overlap Wheelock
       -- mean colors between hemispheres
       -- duplicate whole tiles
6. Comparison to External Catalogs

      XSC Huchra
      NOAO wide deep Cutri - to help Stiening?
      Sloan Kirkpatrick, Skrutskie

7. General and Sanity Checks

   - Range Checking Tam
   - All sky flux, counts, and color maps Jarrett (XSC)
   - Comparison to Galactic star counts models Price
   - Angular correlation functions and edge detection Weinberg
   - Linearity (comparison with deep coadds) Cutri,Kopan