Dear All,<div><br></div><div>just some update on progresses with KIDSCAT . </div><div><br></div><div>I just finished to implement star/galaxy separation (S/G), and I'm rerunning it over all the 52 catalogs.</div><div>Just to remind you that the S/G algorithm is meant to be a simple one, to obtain a "reasonable" (i.e. general purpose)</div>
<div>separation of the two classes.</div><div><br></div><div>The attached plot shows an example of how S/G works. The plot shows CLASS_STAR from S-Ex (second-run cartalog)</div><div>as a function of MAG_AUTO S/N ratio. </div>
<div>In the S/N range where sure stars are available (red dots in the plot), the code applies the biweight estimator to define the </div><div>CLASS STAR location, theta, and its width, sigma. Then we define a lower envelope as theta-4sigma. If S/N is below that of</div>
<div>sure stars, we compute a running median trend, including only objects with CLASS_STAR>0.8, and shift it downwards to match</div><div>the theta-4sigma locus.</div><div>The resulting blue curve in the plot defines the separation of stars and galaxies (i.e. objects with CLASS_STAR > and < the blue curve</div>
<div>are tagged as stars and galaxies, respectively).</div><div><br></div><div>The blue curve is stored in an output file, OUTPUT_RES/SG_CURVE.dat (ascii format).</div><div>The attached plot is automatically produced for each coadd (PLOTS/SG.ps).</div>
<div>The 2DPHOT FLAG in the catalog is updated accordingly. If an object is classified as a star, the 2DPHOT flag value is 4. Different </div><div>flag values are summed up (e.g. 2DPHOT_FLAG=5 means the object is a sure star, and is also classified as star according to </div>
<div>the above procedure).<div class="gmail_quote"><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div></div></blockquote><div> </div><div>Pls, lemme know whatever feedback/comments you have, so that I can change program/scripts accordingly. Also, if you like,</div>
<div>I can share the (fortran) code.</div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<div></div></blockquote><div> </div><div>The catalogs of stars and galaxies will then be used to define completeness...........</div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<div></div></blockquote><div> </div><div>Cheers,</div><div>Francesco</div><div><br></div></div><br></div>