Data Products HOME INDEX SEARCH HELP NEWS

In the different data releases the following data products are made publicly available in different combinations. Imaging data is restricted to ESO member states for an one year period. Bulk data are only available upon request.  

Prompt Release:

A quick-look release consists of reduced images and usually also the associated catalogs. The reductions have been done carefully and the data are probably the best we can provide a short time (usually between one and two month) after the observations have been finished. It should be noted for the quick-look stage, that the level of verification of the results (especially for the catalogs) is very low. The data should be used carefully. Reports about problems with the data are more than welcome. 

---

Single Frames:

Sky-subtracted, fully calibrated frames, in integer format (FITS format). They can be retrieved only on request (Request Form). The requests will be handled by the Science Archive Group. However, an example image (and related catalog) of Patch A (I-band) is available at the ESO Server for the EIS Example

Note that the calibrated images being distributed have not been corrected for cosmetic defects. In particular, they contain bad columns, cosmic rays and the vignetted region at the top and bottom edges of the frames. However, all of these artifacts have been taken into account in the production of the object catalogs and the information available in them allows one to filter out affected objects.

To provide approximate astrometric information the CD-matrix convention, as given in the Users Guide for the Flexible Image Transport System 1997 version 4, has been adopted to describe the world-coordinate system, and included in the fits header of each frame. Even though this is in general a reasonable approximation it is not appropriate to account for the distortions of the frames. Therefore,when object catalogs are overlayed onto the images some residuals are visible, especially at the corners of the images.

The photometric zero-point for each frame after the absolute photometric calibration of the frame appears in the header of the image. A full description of the EIS specific keywords is also provided. 

---

Dedithered Images:

Dedithered images are results of coadding a consecutive group of frames with almost the same pointing onto a common grid. The following assumptions are used to define the groups:
• the minimum time interval is set to 120 sec. If two pointings have a time separation greater than the minimum time interval, they are categorized into two different groups . This is to cope with short (<60 sec) exposures.
• Moreover 2 consecutive pointings are being categorized into two different groups if the difference in right ascension or in declination of the 2 centers is greather than 20 arcmins.

---

Coadded Sections:

Sky-subtracted, fully processed sections of the coadded image (ESO Server for EIS coadded Images).

These sections are mapped using the conic equal area (COE) projection (Greisen & Calabretta 1996). Note that this projection is not handled by all display-tools but has already been implemented in the ESO SkyCat.

The available images are lossy compressed using a HCOMPRESS library originally written by White (1992) for the STScI. The coadded sections have been compressed using a very high compression scale of 200 (scale 20 in the case of WFI sections). In addition to the compression, the images are re-sampled by a factor of 0.5 in both directions using the re-sampling code developed by Devillard (1997), which is part of the eclipse library. To perform these conversions we have used a program written by Allan Brighton.

Of course the compression is well visible in the resulting images (see compression tests), but in direct comparison it is very hard to even find a single object suppressed in the compressed version.

 These sections are handled by an on-line server, similar to that avaiable for the Digital Sky Survey. A preliminary object catalog, containing only position and shape information is also available on an on-line server. For the display of the sections and the catalog SkyCat can be used as an interface (you need to configure it properly to make the EIS catalogs available). 

---

Low-resolution Coadded Images (mini images and mini-weights):

Sky-subtracted, fully processed coadded image (ESO Server for EIS Low Resolution Coadded Image).

This image is meant to give a general overview of the whole patch and it has been produced by rebinning (3 arcsec pixel size) and coadding the sections. This is a standard output of the pipeline (~25 Mb). 

---

Cluster Cutouts

Cutouts extracted from coadded images and centered on EIS cluster candidates. There are two different resolutions available:
• Full resolution cutouts with a fixed size of 7' x 7' and a filesize of about 9 MB
• Lossy compressed cutouts produced on-the-fly by the ESO Server for EIS coadded Images.
Both types of cutouts may be requested by completing the request form. After submission of the request you will enter a page containing the 4-sigma detection limit table presented in Olsen et al. 1998. In that page you have the possibility to select to retrieve either the full resolution or the compressed version of the cutout.

 The latter type of cutout you may also retrieve by entering the EIS cluster candidate name in the Object/Cluster Name field of the query form. By using this form you may specify different sizes of the cutout.

A preliminary list of EIS cluster candidates is presented in Olsen et al. 1999. 

---

Single Frame Catalogs:

Object catalogs associated to each single frame. They are provided as FITS binary tables and as ASCII tables with Unix style record terminators. As for the images, also the single frame catalogs can be retrieved on request only (Request Form). The requests will be handled by the Science Archive Group. One example image (and the related catalog) of Patch A (I-band) is available at the ESO Server for the EIS Example

The name convention of the catalogs and single frame images are based on the EIS tiles A(i,j). Where i and j refer to row and column numbers of the observation, respectively. For a full description of the parameters available see the data release accompanying paper (Nonino et al. 1998).

---

Dedithered Images Catalogs:

Object catalogs based on the dedithered images. They are provided as FITS binary tables. In the tables there is a description of all configuration parameters used by Sextractor, in addition the parameter file lists the parameters requested from Sextractor. 

Send comments to <eisadm@eso.org>  Last update: Feb 13, 2001