| OBSERVATIONS OF THE HAWAII HDF-N FIELD |
| Spectroscopy of the ACS GOODS Area of the HDF-N |
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The region around the HDF-N was intensively observed spectroscopically
by a number of groups using the Low-Resolution Imaging Spectrograph (LRIS)
on the Keck 10m telescopes.
This was a labor-intensive effort, since typically only 20-30 sources
could be observed in each mask, and 1 hr observations
were required. However, spectra were obtained for 671 sources
(see the compilation of Cohen et al. 2000).
The recent implementation of the Deep Extragalactic Imaging Multi-Object Spectrograph (DEIMOS; Faber et al. 2003) on the KeckII 10m telescope has greatly increased the speed with which such observations may be carried out. DEIMOS can observe around 100 or more sources per mask, and its higher resolution and quantum efficiency make identifications more straightforward. The long axis of the field-of-view of the instrument is well matched to the 18 arcminute long axis of the ACS-GOODS field, and most of the ACS-GOODS field can be covered in two DEIMOS pointings. With DEIMOS it should be possible to identify nearly all of the sources with optical AB magnitudes brighter than 24 in the red through the entire ACS-GOODS area and many sources at still fainter magnitudes. Recognizing this, two parallel efforts were begun in Spring 2003 to spectroscopically map the galaxies in the ACS-GOODS area with DEIMOS. A team led by Keck astronomers (hereafter, the Team Keck Redshift Survey or TKRS) focused purely on an R magnitude selected sample in the ACS-GOODS region, using observing and reduction techniques developed for the DEEP-2 project (Davis et al. 2003). This sample is described in the paper by Wirth et al. (2004). Catalogs and more information may be found at LINK. Our own sample was embedded within observations targeted at high-redshift galaxies and X-ray and radio selected galaxies in the wider regions, as described in other parts of this site. Free regions of the masks that lay within the ACS-GOODS area were filled with magnitude selected samples chosen to have z' < 23.5, R < 24, or B < 24.5. Some fainter sources were also included where no suitable brighter targets could be obtained. Combining our DEIMOS data with our LRIS data from earlier runs, we now have spectroscopic identifications for 787 sources in the field with z' < 24, R < 24.5, or B < 25. Combining this sample with data from the literature increases the identified sample to 1180 while combining the present and published data with the TKRS sample provides identifications for almost 2000 sources. Tables of the Hawaii sample only and of all identified sources may be found in the tables page. |