The mosaic of  21 ISAAC tiles included in this release is overlaied (in cyan) on the HST/ACS GOODS z-band mosaic.  Each ISAAC field is 2.5 arcmin across.  J&Ks observations in the red tiles are scheduled in P73-P74 (Fall 2004).  The green box indicates the Hubble Ultra Deep Field (H-UDF). [Click to get full size image]

J-band and Ks-band mosaics and corresponding weight maps of the 21 ISAAC tiles (click on the image to see it full size). See also a cut-out of the HUDF region extracted from the Ks-mosaic.

Content of this release

All ISAAC tiles can be overlaied onto any image with WCS information using the attached region file (DS9 format).

Comparison to previous release(s)
This release is the second of this survey. It revises and significantly extends the release of April 9, 2002. The first release consisted of 8 fields in J, H and Ks (Fields 09, 10, 11, 14, 15, 16, 20, 21). The present one consists of a new reduction of these same 8 fields, with the addition of 13 new fields in J-band and 15 new fields in Ks. Note the suffix 'n' (new) for the fields 25n and 26n is due to a re-arrangement of the ISAAC mosaic in the initial stage of survey to ensure maximum coverage of the GOODS/CDFS area within the time allocation. Reduced observations  in the original field positions (as part of programme ID 168.A-0485(E)) are also included in this release (~5 hours in Ks band only in fields named F25,26).
The main areas of improvements in this release were:
1) technique to remove cross-talk effects;
2) ways of building reduction blocks, i.e. sub-groups of frames with homogeneous data quality which are stacked together;
3) uniform photometric calibration across the entire surveyed area
4) improved accuracy of the astrometric solution, now locked on the World Coordinate System defined by the HST/ACS GOODS observations.

Detailed comparisons between the old and new data sets will be presented elsewhere. At the moment it suffices to say that for J- and Ks- band data, the present release superseeds the GOODS/EIS data release 0.5.

Anticipated future releases include the H-band reduced data, the remaining 9 ISAAC/GOODS tiles (F01, 02, 06, 12, 17, 18, 28, 29, 32), ZPs evaluated from observations of photometric standard stars, and source catalogs. 

Notes on v1.0 Data Release

Data reduction method

Each field is the co-addition of a number of sky-subtracted frames (TOT-IMAG in the image header) grouped in a number of Reduction Blocks (RB in the table below). Images are registered using an accurate astrometric grid defined by an R-band ESO Wide Field Imager (WFI) image of the CDFS. 

• Astrometric Solution: The astrometric calibration was derived using as reference catalog generated from a deep WFI-R image which was astrometrically calibrated using the GSC2.3 reference catalog.  The astrometry has been compared by the GOODS team with calibrated data from the Hubble Space Telescope (HST) Advanced Camera for Surveys (ACS). These comparisons yield rms scatter in astrometry of 0.1'' across the entire area.
  All images have a pixel scale of 0.15", which is exacyly a factor of five larger than the pixel in the GOODS/ACS images.
  
  
• Photometric Zero Points (ZPs): The photometric calibration of the present data was made by the GOODS team using the image mosaic constructed from a mosaic of photometrically calibrated SOFI images of the EIS-DEEP and DPS infrared surveys conducted over the same region. The SOFI images (5'x5') encompass a number of tiles of the ISAAC mosaic (2.5'x2.5' each), yielding more robust relative
  calibration across the entire surveyed area. A zero point for each ISAAC field was determined from the SOFI images using a sample of ~50 stars identified in the HST/ACS images. All ISAAC and SOFI images were first PSF-matched to the common value of 0.9 arcsec (worst seeing in the SOFI images), then aperture magnitudes of these stars were used to determine a ZP for each individual tile in the AB system. This procedure yielded ZPs with typical RMS scatters of 0.03 magnitudes in J-band and 0.05 magnitudes in Ks-band. ZPs and RMS values determined in this fashion are listed in the table below, as a full log of the calibration procedure. However, note that to provide a homogeneous photometric ZP across the entire GOODS field, we have rescaled all images to the same ZP of 26.0 in the AB system. Corresponding keywords in the fits headers have been set accordingly, ZPMOSAIC=26.0, ZPMOSSYS=AB, while ZPMOSERR has been set to the aforementioned typical RMS value for J an Ks. The exposure times are also normalized to unity (EXPTIME=1), so that AB magnitudes in all released fields, including the mosaics, can be obtained as:  mag(AB)=-2.5*Log(flux)+ZP .
  To determine systematic errors in this calibration procedure, independent/crossed photometric calibrations are needed on the SOFI and ISAAC data. The SOFI ZPs were found consistent (within a few percent) with  2MASS photometry of a limited number of stars in the field.  A comparison  with photometry from the K20 survey (Cimatti et al. 2002) in a limited area suggests that the ZP in field F16 might have an offset of  up to 0.1 mag (the ZP in this release being fainter). The evaluation of ZPs from observations of photometric standard stars (available in the ESO Archive) is planned in future releases. We encourage the user community to communicate to the GOODS/EIS team any relevant information on this topic.
  
  
• Image Mosaics: in addition to the individual image tiles, this release also includes mosaics of the co-adjoined tiles as single fits files in J and Ks bands, as well as corresponding weight-maps. The WCS information and accuracy of the individual tiles is preserved in these mosaics. A uniform ZP of 26.0 can be used (e.g. with SExtractor) across the entire field, however, it is important to note that the PSF varies from tile to tile within each mosaic (see table below).  In the absence of proper aperture corrections or PSF matching procedures, this would impact efforts to create multi-color catalogs. The J and Ks mosaics have slightly different dimensions, however they can be readily registered using the intrinsic WCS information.
  

Field band Seeing  ZEROPT   RMSZP   #img    ExpT    #RB
-------------------------------------------------------
F03    J    0.42   25.805   0.035    105    12600    3   
F04    J    0.44   25.862   0.029    105    12600    4   
F05    J    0.43   25.884   0.041    105    12600    4   
F08    J    0.45   25.883   0.039    106    12720    4   
F09    J    0.36   26.068   0.030    105    12600    4   
F10    J    0.51   25.975   0.026     68    12240    4   
F11    J    0.46   25.971   0.027     64    11520    3   
F13    J    0.43   25.892   0.029    105    12600    4   
F14    J    0.45   26.044   0.031    105    12600    4   
F15    J    0.47   25.901   0.046     64    11520    4   
F16    J    0.41   25.595   0.036     60    10800    3   
F19    J    0.59   25.791   0.027    126    15120    5   
F20    J    0.46   26.083   0.036     83     9960    3   
F21    J    0.40   26.009   0.033    125    15000    5   
F22    J    0.56   25.923   0.028    110    13200    4   
F23    J    0.45   25.872   0.085     75     9000    3   
F24    J    0.48   25.777   0.057    105    12600    4   
F25n   J    0.60   25.874   0.027    105    12600    4   
F26n   J    0.55   25.828   0.032    106    12720    4   
F30    J    0.66   25.803   0.031    105    12600    4   
F31    J    0.51   25.691   0.031    105    12600    4   

Field band Seeing  ZEROPT   RMSZP   #img    ExpT    #RB
-------------------------------------------------------
F03    Ks   0.55   25.927   0.039    160    14400    4   
F04    Ks   0.50   25.901   0.057    150    13500    4   
F05    Ks   0.55   25.855   0.031    220    19800    6   
F08    Ks   0.40   26.029   0.077    231    20790    6   
F09    Ks   0.39   26.064   0.063    240    21600    6   
F10    Ks   0.45   25.978   0.051    220    22000    8   
F11    Ks   0.44   25.970   0.038    248    24800   10   
F13    Ks   0.38   25.878   0.043    200    18000    5   
F14    Ks   0.48   26.049   0.051    241    21690    8   
F15    Ks   0.49   25.982   0.057    275    27500   10   
F16    Ks   0.55   25.572   0.050    215    21500    7   
F19    Ks   0.46   25.916   0.038    192    17280    6   
F20    Ks   0.39   26.050   0.041    240    21600    6   
F21    Ks   0.39   26.059   0.026    240    21600    7   
F22    Ks   0.54   26.035   0.026    239    21510    6   
F23    Ks   0.48   25.817   0.028    240    21600    6   
F24    Ks   0.50   25.872   0.033    198    17820    5   
F25    Ks   0.59   25.938   0.048     70     6300    2   
F26    Ks   0.52   25.974   0.084    116    10440    3   
F25n   Ks   0.45   25.860   0.037    167    15030    4   
F26n   Ks   0.51   25.880   0.073    224    20160    6   
F30    Ks   0.40   25.842   0.099    233    20970    6   
F31    Ks   0.31   25.867   0.047    234    21060    6   

Data format

Note: Filenames of the 46 images retrieved through the Science Archive have  EIS based, time stamped names. Field names can be found in the OBJECT keywords in the fits headers (the TILEID keyword can be ignored). For convenience, we provide  this file to associate these files to each GOODS field. For example, to rename the orginal filenames to more user friendly names one could use the unix command:

cat list_v1.txt | awk '{print "mv",$1,$2".fits"}' |csh

Acknowledgements

Send comments to <goods@eso.org>  Last update: May 06, 2004