The NTT SUSI Deep Field, Catalogue Description

The catalogue of the NTT Deep Field, here available as ASCII file, has been processed with the SExtractor algorithm (E. Bertin, 1996) and contains 608 objects.

References and information about the detection, photometry and properties of the sample can be found in the paper by Arnouts, D'Odorico, Cristiani, Zaggia, Fontana, Giallongo, 1998, astro-ph/9810135 (hereafter ADCZFG). Short explanatory notes are given below.

1. The detection of sources has been done on the image resulting from the sum of the four weighted frames (B, V, r, I).

The detection is performed by convolving the reference frame by the PSF and then thresholding it at 1.1 sigma of the background r.m.s. (see section 2.3.1 in ADCZFG). For quantitative analysis, border areas with larger noise due to the combination of dithered exposures with shorter integration times should be used with caution.

2. The total magnitudes are isophotal magnitudes (at 1 sigma) if the isophotal area is larger than 2.2 arcsec aperture (17 pix) or they are measured inside the 2.2 arcsec apertures corrected to 5 arcsec by assuming stellar wings. They are in natural photometric systems (see section 2.2.2 in ADCZFG) and galactic absorption has been applied (see section 2.3.1 in ADCZFG). Objects with computed magnitudes fainter than the expected magnitude limits at 1 sigma in 2.2 arcsec aperture (B_lim~28.2, V_lim~27.7, r_lim~27.0, I_lim~26.3) have been assigned an upper-limit and a value of -1 is entered for the associated error.

3. Shape parameters in columns #18 to #26 are given from the I image which has the best seeing.

4. Colours have been computed by the difference of adaptive apertures for bright objects (isophotal area > 180 pixels, I<=23) and for the faintest ones inside the 2. arcsec apertures (~15 pixels). For these measurements the I frame has been degraded to the worst seeing of the B band.

All colours are given in AB system (see section 2.2.2 in ADCZFG). For objects defined as upper-limits in the 2. arcsec aperture at 1 sigma, the colours are also upper-limits and the colour errors are put at negative values.

For example, colour = B-A
if B is upper-limit and not A, err=-1
if A is upper-limit and not B, err=-2
if B and A are both upper-limits, err=-3

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Description of the Catalogue

  Column    Name             Description
-----------------------------------------------------------------
  #1 :      IDENT            number of objects 
  #2 :      X                position (in pixel)
  #3 :      Y                position (in pixel)
  #4 :      RA  (hour)       Right Ascension, equinox 2000 
  #5 :      RA  (min)
  #6 :      RA  (sec)
  #7 :      Dec (degree)     Declination, equinox 2000
  #8 :      Dec (min)
  #9 :      Dec (sec)
  #10:      B                total magnitude in natural system  
  #11:      err_B            error 
  #12:      V                total magnitude in natural system
  #13:      err_V            error
  #14:      r                total magnitude in natural system 
  #15:      err_r            error
  #16:      I                total magnitude in natural system
  #17:      err_I            error
  #18:      FWHM             Full Width Half Maximum (in pixel)    
  #19:      FLAG             SExtractor FLAG 
  #20:      CLASS            STAR / GALAXY Classifier 
  #21:      MAJOR_AXIS       Semi major axis length (in pixel)
  #22:      MINOR_AXIS       Semi minor axis length (in pixel)
  #23:      THETA            Angle (in degree)
  #24:      ELONGATION       (A/B)
  #25:      ELLIPTICITY      (1 - B/A)
  #26:      AREA             Isophotal area (in pixel)
  #27:      B_V              Colours in apertures of 15 pixels in AB system  
  #28:      err_B_V          Quadratic error
  #29:      B_R              Colours in apertures of 15 pixels in AB system  
  #30:      err_B_R          Quadratic error 
  #31:      B_I              Colours in apertures of 15 pixels in AB system  
  #32:      err_B_I          Quadratic error
  #33:      V_R              Colours in apertures of 15 pixels in AB system  
  #34:      err_V_R          Quadratic error 
  #35:      V_I              Colours in apertures of 15 pixels in AB system  
  #36:      err_V_I          Quadratic error
  #37:      R_I              Colours in apertures of 15 pixels in AB system  
  #38:      err_R_I          Quadratic error