Readme file for the catalogue UDS_DR11_K_gala.fits This catalogue contains the structural parameters determined from the UDS DR11 K-band image. These parameters were obtained via single Sérsic fits using GALAPAGOS-2 and GALFIT3. Information on the columns is included below. For now, the most appropriate reference describing the generation of these data is Almaini et al. (2017). Recommended QC cuts ------------------- For most purposes we recommend applying use the following cuts to the data, to remove masked regions, stars, and detector cross-talk respectively: mask== false Stars-final == false XTALK-DR11== false We also recommend excluding data at the extremes of the size/Sérsic parameter distribution, as these will be constrained fits, which we have found to be less reliable. In Topcat, the cuts can be applied as follows: RE_GALFIT_BAND>0.100005 N_GALFIT_BAND<8 && N_GALFIT_BAND>0.200001 Finally, we recommend restricting the analysis to galaxies with K-band magnitudes K<24. (KMAG_20<24). A comparison with HST CANDELS and JWST-PRIMER data reveals that the structural parameters are unreliable at the faintest magnitudes. For convenience, a restricted catalogue has been generated with the constraints above already applied. This version is likely to be the most useful for most applications: UDS_DR11_K_gala_RECOMMENDED.fits Additionally, the poorest fits can be further excluded (if required) using the chi^2 parameters, e.g. CHI2NU_GALFIT<100 Note: while errors on the GALFIT structural parameters have been provided, these are known to be underestimated (Häussler et al. 2007), so should be used with caution. ______________________________ col. Parameter 1 DR11_ID UDS DR11 ID 2 ALPHA_J2000 DR11 RA (UKIDSS frame) 3 DELTA_J2000 DR11 DEC (UKIDSS frame) 4 KMAG_20 DR11 K magnitude (AB; 2 arcsec aperture; corrected to total) 5 z_use DR11 redshifts 6 mask DR11 JHK bad pixel mask 7 Stars-final Candidate galactic stars 8 XTALK-DR11 WFCAM cross-talk (or objects contaminated by cross-talk) 9 gala_run GALAPAGOS run sample 10 GALA_ID GALAPAGOS: ID 11 ELLIPTICITY SExtractor: ellipticity 12 KRON_RADIUS SExtractor: Kron radius 13 A_IMAGE SExtractor: semi-major axis (use with Kron radius) 14 B_IMAGE SExtractor: semi-minor axis (use with Kron radius) 15 FLAGS SExtractor: flags (see SExtractor manual) 16 CLASS_STAR SExtractor: star/galaxy Classifier 17 SKY_GALA_BAND GALAPAGOS: sky level 18 SKY_SIG_BAND GALAPAGOS: error on sky level 19 SKY_RAD_BAND GALAPAGOS: radius at which sky determined (pixels) 20 FLAG_GALFIT GALFIT: Flag (0 = fit not attempted; 1 = fit crashed; 2 = fit sucessful) 21 CHISQ_GALFIT GALFIT: Chi^2 of the fit 22 CHI2NU_GALFIT GALFIT: reduced Chi^2 of the fit 23 SKY_GALFIT_BAND GALFIT: sky value used in the fit 24 X_GALFIT_BAND GALFIT: x-position in postage stamp 25 XERR_GALFIT_BAND GALFIT: error on x-position in postage stamp 26 Y_GALFIT_BAND GALFIT: y-position in postage stamp 27 YERR_GALFIT_BAND GALFIT: error on y-position in postage stamp 28 MAG_GALFIT_BAND GALFIT: magnitude 29 MAGERR_GALFIT_BAND GALFIT: error on magnitude 30 RE_GALFIT_BAND GALFIT: effective radius (pixels) 31 RE_GALFIT_BAND_ARCSEC GALFIT: effective radius (arcsec) 33 REERR_GALFIT_BAND GALFIT: error on effective radius (pixels) 33 REERR_GALFIT_BAND_ARCSEC GALFIT: error on effective radius (arcsec) 34 N_GALFIT_BAND GALFIT: Sersic index 35 NERR_GALFIT_BAND GALFIT: error on Sersic index 36 Q_GALFIT_BAND GALFIT: axis ratio (b/a) 37 QERR_GALFIT_BAND GALFIT: error on axis ratio 38 PA_GALFIT_BAND GALFIT: position angle 39 PAERR_GALFIT_BAND GALFIT: error on position angle