Phase 3 Policies for ESO VST Public Surveys

Following from the agreement signed by the ESO Director General and the PIs of the VST public surveys, the delivery of the data products to the ESO archive from an ESO Public Survey is the responsibility of the PI, which certifies the scientific quality and accuracy of the data products.

Survey products will be delivered to the ESO archive in a format specified in the ESO Science Data Products standard [PDF], which is accessible from the top-level Phase 3 web page. Please be aware of the improvement and changes on the data interface associated with the Phase 3 upgrade; more information available at these web pages:
http://www.eso.org/sci/observing/phase3/upgrade_summary.html
and
http://www.eso.org/sci/observing/phase3/faq.html

According to the general Phase 3 policy for ESO public surveys, the PIs of the three VST public surveys are invited to submit their data products based on observations that were completed six months before the opening date for submission.

  • The first Phase 3 submission of images, weight-maps and source lists from the VST public surveys occurred between March and May 2013.
  • The second Phase 3 submission, catalogue, images, weight maps and source lists occurred between October and November 2014
  • The third Phase 3 submission, catalogue, images, weight maps and source lists occurred in 2016 and 2017

Upcoming Phase 3 Submission

The next Phase 3 submission for VST public surveys products including images, single-band source lists and multi-band catalogue data will be open between

June 1st and July 31st, 2018

after which the data will be validated, archived and published for access by the ESO community in due course.

The PIs of the three VST public surveys are invited to submit their data products including all observations, which have been completed on a tile-by-tile basis before the reference date June 1st, 2017.

Summary of VST public survey deliverables

The required deliverables are astrometrically and photometrically calibrated tile images/pawprints with their associated weight maps, single-band source lists, and, starting with the 2nd data submission, multi-band object catalogues including the photometry in all filters relevant to the specific programme.

The table hereafter lists a short description of the data product deliverables. A final release (after fifth year) is expected for all surveys.

Summary of the deliverables for data submission #1 of the VST Public Surveys

Survey

Deliverable #1

Tiles and confidence map

(mandatory)

Deliverable #2

Single band source lists for each tile

(mandatory)

Deliverable #3

Aperture-matched multi band catalogues

(mandatory)

Deliverable #4

Ancillary gain maps

(recommended)

ATLAS u, g, r, i, z u, g, r, i, z yes yes
KIDS
u, g, r, i u, g, r, i yes yes
VPHAS+ u, g, r, i, Halpha u, g, r, i, Halpha yes yes

Content of VST public survey catalogues

Multi-band source catalogues including all the photometric bands relevant to each project are primary deliverables for all VST public surveys. The precise content of the catalogues to be delivered will depend on the scientific goals and exploitation possibilities of each VST public survey programme. The submission of further catalogue data beyond the core deliverables indicated above is most welcome during Phase 3. All data must be accompanied by the necessary documentation.

  • We request from the PI to define one unique source identifier (ID), preferentially according to the IAU recommendations for nomenclature using the schema
PREFIX hhmmss.s(s)±ddmmss.s(s)

where PREFIX denotes the survey programme. The consistent definition of (IAU) source names throughout related publications is important to ESO archive users because it enables the efficient exploitation of the data using the catalogue query interface.

In case of degenerate catalogues, where IAU names are not guaranteed to be unique, the unique source ID should be defined in terms of a positive integer number (>0) within a dedicated column. The IAU name should be included in an additional column.

The source ID serves as a reference key and must be recorded in any catalogue that contains measurements for the given source, including multi-epoch photometric data collections (light-curves) and catalogues of variables.

  • Any source catalogue must include Right Ascension and Declination in decimal degrees (J2000) to specify the celestial position of each source.
  • Source positions, apparent magnitudes and colours should refer to the survey-wide (a.k.a. global) astrometric and photometric system established by cross-calibrating the available data using overlapping tiles and across different bands. This implies that magnitudes and colour indices should be corrected for seeing variations across different observations. Single-band catalogues, termed source lists in the context of Phase 3, usually do not qualify for submission as survey source catalogue.
  • The catalogue columns that contains the best estimate of the total flux for a point-like source should be indicated in the release description. The detailed nature of the total flux estimator depends on the scientific goals of the particular survey.
  • Multi-band source catalogues should generally contain colour indices for each source in order to facilitate efficient queries including colour constraints. The survey team is free to identify suitable colours according to their scientific objectives. The colour definitions should be documented in the data release description associated to each catalogue.
  • If some data fields within a catalogue are missing i.e. there is no valid measurement it must be encoded in terms of special values, in particular using the IEEE NaN ('Not a Number') for floating point type of data.

Large Area Surveys

Due to the nature of large area surveys the catalogue data resulting from ATLAS, VPHAS+, KIDS should be submitted in a tile-by-tile fashion, meaning that the entire catalogue is segmented into N separate FITS data files, where each file corresponds to one VST survey tile, plus one metadata file describing the entire catalogue.

Multiple detections of the same source, which occur in the overlap regions of adjacent survey tiles, are expected to be merged in the final multi-band photometric catalogue. Unless the uniqueness of the sources in the band-merged catalogue is being guaranteed, duplicate entries should be consistently flagged throughout the entire catalogue by including a dedicated column ('PRIMARY_SOURCE'), which is set to 1 if the source is a primary one and to 0 otherwise.

Processing provenance

Data providers are requested to include consistent and complete processing provenance information in each science data product file (cf. ESO SDP Standard, Issue 5, Sect. 2.4). PROV references should point to the precursor science data files which have been included into the generation of the given product provided that the referenced files already exist in the ESO archive or they are being submitted as part of the same data release or another release at the same time. The correctness of PROV pointers is an important criterion for data product acceptance.