TITLE OF RELEASE GOODS/ISAAC Survey Release
19 May 2004
TECHNICAL SUMMARY CURRENT RELEASE Survey: GOODS Telescope: ESO/VLT Instrument: ISAAC Program IDs: LP168.A-0485; 64.O-0643; 66.A-0572; 68.A-0544 Origin: ESO/EIS Number of regions: 1 Region: CDF-South Number of Fields: 21 Number of passbands: 2 (J, Ks) EIS Release Number: 18 Version: 1.0 Release Date: May 2004 Release prepared by: GOODS & EIS teams PRODUCTS Product Type: Mosaic, Mosaic Tiles Number of Tiles: 44 Number of Mosaics: 2 Number of images: 46 Number of catalogs: 0 Number of XML files: 0 PREVIOUS RELEASE Origin: ESO/EIS Number of regions: 1 Region: CDF-South Number of Fields: 8 Number of passbands: 3 (J,H, Ks) EIS Release Number: 14 Version: 0.5 Release Date: 9 April 2002 PRODUCTS Product Type: Stacked Images Number of images: 24 Number of catalogs: 0 Number of XML files: 0 Total Volume: 0.2 Gb
ABSTRACT As part of the Great Observatories Origins Deep Survey (GOODS), infrared imaging observations of the Chandra X-ray Observatory Deep Field South (CDF-S) are being carried out in J-, H- and Ks- bands, using the ISAAC instrument mounted at the Antu Unit Telescope (UT1) of the VLT at the ESO Cerro Paranal Observatory, Chile. These data are being obtained as part of the ESO Large Programme: LP168.A-0485(A) (Principal Investigator: C. Cesarsky). Data covering 4 ISAAC fields in J- and Ks- bands are also available from the ESO programmes 64.O-0643, 66.A-0572 and 68.A-0544 with E. Giallongo as the principal investigator. Since ISAAC observations are still ongoing, this release consists of J and Ks images of fields that have already been completed and are available in the ESO Science Archive Facility up to the end of ESO observing period 72 (effectively 9 March 2004). This data release includes 21 fully reduced VLT/ISAAC fields in J- and Ks- passbands (but see notes on fields 25/25n and 26/26n in the COMPARISON TO PREVIOUS/LATER RELEASE(S) section of this document), covering 131 square arcminutes of the GOODS/CDF-S region, as well as 2 mosaics in the J- and Ks- passbands. As part of the overhaul of the EIS web service, commenced during 2003, the transfer of survey products to the ESO Science Archive Facility and the EIS web publishing mechanism has been wholly automated. Any errors that may have been introduced during this procedure shall be addressed in due course, and in response to notifications from the EIS user community. As with all ESO public surveys, survey raw data become public immediately to registered users of the ESO Science Archive Facility, while reduced data and survey products are made available as soon as processed via the EIS survey system. CONTENTS OF THIS RELEASE This release is the second associated with the GOODS survey. It revises and significantly extends the previous (first) release (version 0.5) of 9 April 2002. The first release consisted of 8 fields in J, H and Ks. The present release includes astrometrically calibrated, photometrically calibrated and appropriately re-scaled individual tiles (see STANDARD EIS DEFINITIONS, CONVENTIONS AND DATA FORMATS section of this document) which, when co-adjoined, form 2 large-scale mosaics, corresponding to 21 (13 new) fields in J-band and 23 (15 new) fields in Ks-band. This release also contains the resultant 2 large-scale (J-band and Ks-band) mosaics, with accurate astrometric solutions and uniform photometric zero points (see DATA REDUCTION section of this document) formed by co-adjoining individual tiles in the same passband. Thus, a total of 46 image products form the core of the this release. In compliance with EIS standards (defined in the STANDARD EIS DEFINITIONS, CONVENTIONS AND DATA FORMATS section of this document) image products are available in FITS format. Files have EIS-based, time-stamped names. Each FITS file consists of 2 extensions: the first extension contains the science-grade image; the second extension contains the corresponding weight map, defined as a variance map (e.g. it should be used with SExtractor using the parameters: -WEIGHT_IMAGE weight_map.fits -WEIGHT_TYPE MAP_WEIGHT). Field names can be found in the OBJECT keyword of the FITS header. For convenience, the GOODS team provides a translation protocol to associate standard EIS products to each GOODS field. The World Coordinate System (WCS) information and accuracy of the individual tiles is preserved in the mosaics. A uniform zero point 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. In the absence of proper aperture corrections or PSF-matching procedures, this would impact efforts to create multi-colour catalogs. These mosaics have slightly different dimensions, however they can be readily registered using the intrinsic WCS information. More specific information can be found in supporting documentation provided by the GOODS team:
RETRIEVING EIS PRODUCTS: GENERAL Official EIS products can be retrieved via two alternate routes, both originating at the EIS home page: http://www.eso.org/science/eis/eis_home.html This page indexes all EIS surveys, listing some of their most important characteristics and presents a navigation menu, spanning the width of the browser window. From the indexed list of surveys at the EIS home page, the survey of interest can be selected via a hypertext link embedded in the survey name. This action accesses a more detailed description of the survey, including information about differing strategies (if applicable). Within this page, another horizontal navigation menu can be found. Selecting the RELEASE link of this menu connects to a reverse chronological index table of official EIS data releases for the pre-selected survey. This table lists the following entries (whenever available): (1) The (hyperlinked) integer index number of the release; (2) a composite of the release version (first 2 values separated by a point; see STANDARD EIS DEFINITIONS, CONVENTIONS AND DATA FORMATS below), appended where appropriate with the release revision number (an integer value) trailing a second point; (3) the date the products entered the ESO Science Archive Facility repositories (effectively the date of public release); (4) the total volume (in Gigabytes) of the complete release package; (5) an indication that the release products include catalogs; (6) an indication that the release products include images; (7) an indication that the release products include a list of astronomical targets classified to be of potential scientific interest (e.g. clusters of galaxies, QSO candidates, brown dwarf candidates, etc.) if applicable, drawn from the release survey products (to be implemented); (8) a hyperlink to the content of the .README file which documents the selected release in detail. Selecting the hyperlinked index number in column (1) presents the final element of the data release infrastructure: a full list of products available in the selected release from which all products, or individual products can be selected interactively (see below for more details). Alternatively, from the navigation menu, spanning the width of the browser window, selecting the SURVEY RELEASE link connects to a reverse chronological index table of official EIS data releases for the pre-selected survey. This table while similar, is not identical to that described above, and lists the following entries (whenever available): (1) The (hyperlinked) integer index of the release (i.e. "EIS release number"); (2) a description of the product type (e.g. data, software); (3) a description of the products (e.g. survey name, software name) (4) a composite of the release version (first 2 values separated by a point; see STANDARD EIS DEFINITIONS, CONVENTIONS AND DATA FORMATS below), appended where appropriate with the release revision number (an integer value) trailing a second point; (5) the date the products entered the ESO Science Archive Facility repositories (effectively the date of public release); (6) the total volume (in Gigabytes) of the complete release package; (7) a hyperlink to the content of the .README file which documents the selected release in detail. As before, selecting the hyperlinked index number in column (1) presents the final element of the data release infrastructure: list of products available in the selected release from which, where implemented, all products, or individual products can be selected interactively. The data release infrastructure has been designed to generate a hierarchical sequence of HTML pages to support the differing strategies for a given survey --- and for a given strategy, the range of survey products that may become available, such as images/catalogs (reduced, stacked, mosaic, single passband, colour) and other nightly products (e.g. zero points) as well as advanced survey products such as target lists (as will be exemplified in future releases). The list of products available per release is presented in tabular format in the final element of the data release infrastructure, the first section of which consists of "data release information" (which enables access to general information such as the .README file documenting the selected release in detail; confirms details such as the product description, version, data volume; and reports total numbers of files and fields forming the release). RETRIEVING EIS PRODUCTS: THIS RELEASE In the case of the present release (involving image mosaics and the component image tiles) the "data release information section" is followed by a section detailing the "contents" of the release, listing: (1) a sequential index number (not to be confused with the "Product Identification number" which is reported elsewhere); (2) the EIS standard field/region name with an associated hyperlink to a single .JPEG format file showing up to three images of the region/field for purposes of illustration and ratification. These images are ordered by increasing central wavelength of the passband. Where images in more than one passband are available, they are accompanied by a final "RGB" colour composite image (in which "R" is assigned to Ks-band, "G" is assigned to J-band and "B" is also assigned to J-band). The .JPEG format enables image properties such as saturation and intensity to be interactively modified as desired using color editors (e.g. within the "xv" UNIX/Linux utility). (3) the relevant passband; (4, 5) the R.A. and Dec. position; (6) the total integration time (in seconds) contributing to the final product; (7) the total number of science exposures contributing to the final product; (8) a grade (A to D) assigned as an indication of cosmetic quality, during visual inspection of the product by the EIS team; (9) the total volume (in Megabytes) of the selected product; (10) a hyperlink to to a comprehensive descriptive log of the product. (Product logs are planned for phased introduction over a series of forthcoming releases). (11) an interactive check-box which enables the individual product to be selected/de-selected before finally submitting the selection to the ESO Science Archive Facility using "Request Marked Products" at the foot of the page. COMMENTS SPECIFIC TO THIS RELEASE In the case of the interface between the GOODS and EIS teams, inconsistencies are present between adopted usages which while inconvenient, are unavoidable. The following discussion emphasizes specific cases and explains their origin. Ideally, the convention that would normally be adopted by EIS is to name a field when the survey is first defined, using the survey name and/or region as the root, followed by a numerical suffix generated by the particular algorithm used in the construction of the "Observation Block" (OB) and the associated survey strategy (as defined by a set of pointings, instrument and passband). In this way, all possible identifiers of a field utilized by the EIS system both internally and externally (e.g. OB name, object name, target name, field name) and their graphical representations on the EIS web pages form a homogeneous set. Historically however, the conventions have evolved in time due to several factors: * At their outset, prior to the introduction of a systematic global approach, several surveys were defined case-by-case and in isolation. * Over time, some pre-existing and on-going surveys had their geometries changed; methods for addressing positions were reviewed; surveys were extended, amalgamated or otherwise re-defined by altered algorithms --- with the consequent revision of the framework(s) within which the survey(s) were being managed. * In the absence of pre-determined standards, collaborative surveys co-administered by independent groups exhibit differing notations. The interface to a common scheme (when this requirement is inevitably identified) becomes particularly difficult. Hence, in practice, the desired ideal case is not always attainable and requires some retroactive adaptations. The following noteworthy discrepancies between the nomenclature adopted by the GOODS and EIS teams in referring to ISAAC pointings within the CDF-S occur: 1) The convention adopted by EIS is to assign fields and/or regions consecutive numbers at the time of survey strategy definition using an automatic procedure. Currently, EIS assigns regions and/or fields at survey definition according to sequentially increasing R.A. and Dec. positions of the defined pointings. However, this was not always the case. There exist surveys for which addressing information was assigned in isolation at the survey outset and which were also assigned a sequential value to be incorporated into, and referenced by the EIS system at a later date. For these surveys, while the multiple nomenclatures persist simultaneously, sequentially numbered fields and/or regions referred to in EIS indices do not correspond to numerical values which may appear in region and/or field names assigned prior to introduction of the EIS system. Hence in the GOODS survey, for example, the field indexed by the EIS system (including the web service) as "1" does not necessarily correspond to the field name originally defined to be "F01" in the GOODS survey. For example: http://www.eso.org/science/eis/surveys/strategy_GOODS_infrared_deep.html) 2) The current EIS terminology prefaces field numbers with root names derived from the applicable survey name (in this case "GOODS_") whereas the same field numbers are prefaced "F" by the GOODS team. 3) Sequential TILEID numbers (defined in the STANDARD EIS DEFINITIONS, CONVENTIONS AND DATA FORMATS section of this document) appearing in the FITS header of an EIS product are automatically assigned by the EIS system when binding mosaic images and their contributing tiles into a set of related products for a given release. The binding depends on the geometry and completeness of the contributing reduced data. Therefore TILEID numbers do not necessarily correspond to other indices such as the "F" field identifiers used by the GOODS team, or the "GOODS_" field identifiers employed by EIS algorithms. Due to the mosaic nature of the products, the form of the products in the current release departs somewhat from the established EIS form and introduces a number of keywords to the FITS headers to accommodate mosaic information. The most notable features are: * The products in the current release consist of mosaics and their individual contributing tiles. The reported zero point values for all of the released products are re-scaled to a common mosaic value of 26.0 magnitudes. This is in contrast with other EIS releases for which zero points are derived and reported for each product individually. The relevant FITS keywords introduced to accommodate this are defined in the STANDARD EIS DEFINITIONS, CONVENTIONS AND DATA FORMATS section of this document. * In contrast to the Vega magnitude system normally used by default in EIS products, the current data release is calibrated in the AB magnitude system. * For the large-scale (J-band and Ks-band) mosaic images, the integration time reported is the sum of integration times of the individual tiles contributing to the mosaic products. COMPARISON TO PREVIOUS RELEASE(S) Note that the present release includes new reductions of the J- and Ks- fields released earlier. The main areas of improvements were: 1) Techniques to remove cross-talk effects; 2) Methods 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 fixed on the World Coordinate System defined by the HST/ACS GOODS observations. Detailed comparisons between the previous and new data sets will be presented elsewhere. At the moment it suffices to say that the new reductions supercede those of of the previous release (version 0.5) of 9 April 2002. For J- and Ks- band data, the present release supercedes the GOODS/EIS data release 0.5 performed on 9 April 2002 for the following fields: GOODS_09, GOODS_10, GOODS_11, GOODS_14, GOODS_15, GOODS_16 GOODS_20 and GOODS_21. In addition, this release introduces reduced J- and Ks- band data for the following 13 fields: GOODS_03, GOODS_04, GOODS_05, GOODS_08, GOODS_13, GOODS_19, GOODS_22, GOODS_23, GOODS_24, GOODS_25n, GOODS_26n, GOODS_30 and GOODS_31; and the fields GOODS_25, GOODS_26 in Ks. Note the suffix "n" (new) for the fields GOODS_25n and GOODS_26n is due to a re-arrangement of the ISAAC mosaic in the initial stages of the survey to ensure maximum coverage of the GOODS/CDF-S area within the observing time allocation (for ESO programme 168.A-0485(A)). Reduced observations at the original field positions (as part of ESO programme 168.A-0485(E)) are also included in this release (Ks-band only in fields named GOODS_25 and GOODS_26). Thus the Ks-band data includes files associated with both positions 25 and 25n, and both positions 26 and 26n. The J-band data includes files associated with only positions 25n and 26n (i.e. files associated with positions 25 and 26 are not included with the J-band data). In contrast to previous releases (in which the Vega magnitude system is adopted), it should be emphasized that the current release adopts AB magnitude system. Furthermore, the release of re-scaled mosaics and component tiles, as in this release, may not always be practicable (depending on the instrument used), shall not be common EIS procedure. Together, these features represent significant departures from the standard EIS procedure being established (see the STANDARD EIS DEFINITIONS, CONVENTIONS AND DATA FORMATS section of this document). DATA REDUCTION The ISAAC data were reduced using the EIS/MVM image processing library. This software package is publicly available and can be retrieved from the URL: http://www.eso.org/science/eis/survey_release.html Each field is the co-addition of a number of sky-subtracted frames (the TOT_IMAG keyword in FITS image header) grouped in a number of Reduction Blocks (RB). Images are registered using an accurate astrometric catalog extracted from a deep ESO Wide Field Imager (WFI) R-band image of the CDF-S and then warped onto a grid pre-defined to be a convention common for all GOODS program data products. Thus the native pixel scale of ISAAC is re-sampled to 0.15 arcseconds in the reduced products. ASTROMETRY The astrometric calibration was derived using a reference catalog generated from a deep ESO Wide Field Imager (WFI) R-band image which was itself 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 arcseconds across the entire area. All images have a pixel scale of 0.15 arcseconds, which is exactly a factor of 5 larger than the pixel in the GOODS/ACS images. The WCS in the image header is reported using the CD-matrix notation. The projection adopted is TAN and the orientation is north up and east to the left. PHOTOMETRY The photometric calibration of the present data was performed by the GOODS team using a mosaic assembled from SOFI images of the EIS-DEEP and DPS infrared surveys conducted over the same region. The SOFI images (5 x 5 arcminutes) encompass a number of tiles within the ISAAC mosaic (2.5 x 2.5 arcminutes each), yielding a 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 circa 50 stars identified in HST/ACS images. All ISAAC and SOFI images were first PSF-matched to the common value of 0.9 arcseconds (worst seeing in SOFI images), then aperture magnitudes of these stars were used to determine a zero point for each individual image in the AB system. This procedure yielded zero points with typical rms scatters of 0.03 magnitudes in J-band and 0.05 magnitudes in Ks-band. However, note that to provide a homogeneous photometric zero point across the entire GOODS mosaic, all images have been re-scaled to the same zero point of 26.0 in the AB system. Corresponding keywords (see the STANDARD EIS DEFINITIONS, CONVENTIONS AND DATA FORMATS section of this document for definitions) in the FITS headers have been set accordingly, ZPMOSAIC = 26.0, ZPMOSSYS = 'AB' while ZPMOSERR has been set to the aforementioned rms values for J- and Ks- bands. The integration times are also normalized to unity, EXPTIME = 1, so that AB magnitudes in all released images, including the mosaics, can be obtained as: mag(AB) = -2.5*log10(flux) + ZPMOSAIC. To determine systematic errors in this calibration procedure, independent/crossed photometric calibrations are needed on the SOFI and ISAAC data. The SOFI zero points were found to be consistent (within a few percent) with 2MASS photometry of a limited number of stars in the field. The evaluation of zero points from observations of photometric standard stars (available in the ESO Science Archive Facility) is planned for future releases. There remains a suggestion that a zero point offset of up to 0.1 magnitudes might be present in one field only (see the REMARKS ON INDIVIDUAL PRODUCT(S) section of this document). DATA QUALITY ASSESSMENT Before being released images are examined by eye and graded by the EIS team, with the grade range being from A (best) to D (worst). This grade refers only to the visual aspect of the data (e.g. background, cosmetics). For this release, there are 40 grade A images and 6 grade B images. The latter are all in Ks-passband and typically reflect the presence of somewhat enhanced background features. The widespread reporting of graded data shall undergo a phased introduction over a series of forthcoming product releases. Eventually, the grade will also include a larger set of quality control parameters (QCP) and will be available for each survey product via corresponding product logs. The distribution of grades will also become available through the EIS WEB service (via STATISTICS accessible from the release page). REMARKS ON INDIVIDUAL PRODUCT(S) GOODS_16 - A comparison with an independent reduction and calibration performed on EIS/SOFI data by the K20 collaboration (Cimatti et al. 2002) in a limited area suggests that the zero point in field GOODS_16 might have an offset of up to 0.1 magnitudes in the Ks-band (the zero point in this release being fainter). We encourage the community to communicate to the GOODS/EIS team any relevant information on this topic. NEXT RELEASE(S) Anticipated future EIS/GOODS releases include: the reduced H-band data; the remaining 9 ISAAC/GOODS fields (GOODS_01, GOODS_02, GOODS_06, GOODS_12, GOODS_17, GOODS_18, GOODS_28, GOODS_29, GOODS_32); Zero points evaluated from observations of photometric standard stars and source catalogs and the phased introduction of comprehensive product logs. STANDARD EIS DEFINITIONS, CONVENTIONS AND DATA FORMATS The EIS survey system is designed to administer and document (via integration with a robotically maintained web service) multiple surveys and strategies in their entirety, from survey definition to release of science-grade products by nominally operating in unsupervised mode. Achieving this requires the introduction of well-defined procedures to enable adaptive, automatic and sequential addressing of information. These procedures may occasionally lead to conventions (e.g. field/region names) which may not always be intuitive, but are driven by the specific process involved. The most relevant conventions are defined below: REDUCED IMAGE: A "reduced image" is the "nightly" product of a reduction process of a so-called "Reduction Block" (RB). By definition a RB is a group of raw images obtained in the same night which share the same position, passband and form a sequence in time. The content of a RB is usually identical to an executed "Observation Block" (OB) as used in the ESO Data Flow System (DFS). However, the system also allows RBs to be formed by concatenation of similar sequentially executed OBs. In addition individual exposures can be discarded based on configurable constraints on their properties (e.g. background counts, DIMM seeing values, integration time, etc.) STACKED IMAGE: A "stacked image" is the product of an advanced process in which "reduced images" sharing the same instrument, passband and position on the sky are grouped into so-called "Stack Blocks" (SB). In the assembly of SBs, individual "reduced images" can be discarded according to configurable constraints on their properties (e.g. measured seeing, amplitude of PSF distortion, visual grade, OB completeness). The images of the thus assembled SB are re-scaled and accumulated in a weighted co-addition procedure to generate a single final output product. MOSAIC IMAGE: A "mosaic image" (or simply "mosaic") is an image formed from several contiguous (reduced or stacked) "images" produced by the EIS survey system, which have been subsequently re-scaled to share a common zero point and co-adjoined as "tiles" to form a single, large-scale product. MOSAIC TILE: A "mosaic tile" (or simply "tile") is an image (reduced or stacked) produced by the EIS survey system which has been subsequently re-scaled such that it shares a zero point common to other tiles and a large-scale "mosaic image" (or simply "mosaic") of which it forms a component. VERSION: The EIS concept of a release "version" represents a wholesale, global change: either introducing a new set of products, affecting or superceding the quality or properties of more than 5 per cent of previously release products. REVISION: The EIS concept of a release "revision" represents localized changes which may affect individual products with a released data set, while leaving others unaffected. Individual products found to be anomalous may be removed or replaced. New products may be added. The total revisions must not alter more than 5 per cent of a pre-existing set of products. ZPMOSAIC: FITS header keyword ZPMOSAIC contains the value of the zero point (magnitudes) applied to the processed tiles in order to refer instrumental magnitudes to the common photometric system of the mosaic, MOSAICID. The value for ZPMOSAIC is determined by a re-scaling process in which individual reduced images are harmonized to become tiles sharing a common zero point for the entire mosaic. ZPMOSERR: FITS header keyword ZPMOSERR contains the value of the uncertainty (magnitudes) associated with the determination of ZPMOSAIC. ZPMOSSYS: FITS header keyword ZPMOSSYS contains the photometric system in which ZPMOSAIC and ZPMOSERR are expressed. MOSAICID: FITS header keyword MOSAICID contains the the unique identity of the mosaic to which an individual tile belongs to. MOSTILES: FITS header keyword MOSTILES contains the total number of individual tiles contributing to the larger mosaic, MOSAICID. TILEID : FITS header keyword TILEID contains the unique identity of the individual tile within the larger mosaic, MOSAICID. TILEID does not necessarily map directly to any other FITS keyword value (e.g. OBJECT). REFERENCES Cimatti, A., Daddi, E., Pozzetti, L. et al. 2002, Astronomy and Astrophysics, 392, 395 Vandame et al. 2004, in preparation. NOTICE TO USERS OF EIS PRODUCTS * Please report any errors/features found in released products to email@example.com, indicating the product identification number (PROD_ID) found in the FITS header of each image or catalog and/or the time-stamped filename of the product. Comments that may improve the clarity of product distribution are also welcomed. Correspondences to this electronic mail address enter a so-called Action/Request system (ARSystem), are automatically allocated an open "ticket" number, acknowledged, assigned to team members depending on their nature and added to a queue for resolution. Tickets remain open until a resolution is provided. The effective team able to resolve queries is limited and members have other responsibilities. Response times may vary depending on the type of query. * When using products provided by the ESO Imaging Survey either in publications or proposals, EIS requests due acknowledgment. Please follow the copyright instructions, available at: http://www.eso.org/science/eis/copyright.html "Observations have been carried out using the Very Large Telescope at the ESO Paranal Observatory under Program ID(s): ... " * If EIS products or part thereof is/are used or shown publicly, please give proper acknowledgment to the ESO Imaging Survey (EIS) project and, if appropriate, by referring to the relevant EIS publications, available at: http://www.eso.org/science/eis/publications.html * It is recommended that official EIS products are retrieved via the mechanism shared with ESO Science Archive Facility. With a few exceptions, users must be based in an ESO member state and are required to register (free) with ESO Science Archive Facility. Registration details are valid for all subsequent enquires and EIS product requests. Registration and monitoring of requests assists in providing usage statistics, user support and notification of changes which may supercede previously released products. * EIS product releases usually include documentation of known issues and features (e.g. this README document). The dissemination of EIS products to third parties external to the recommended mechanism is strongly discouraged, since such circumventions propagate incomplete and partially documented datasets.