DVO Description

(Up to IPP Description)

Introduction

DVO (the Desktop Virtual Observatory) is a system for manipulating collections of images and measurements related to astronomical objects. The DVO system consists of several programs which insert data in the database system, extract data from the database, or manipulate data in the database. One of these is the DVO shell, which provides a command-line driven, programmable user interface to the astronomical objects and measurements in the database. The DVO shell is based on the Opihi shell language which provides the tools to manipulate and display data in various representations. The DVO shell adds to this basic command set a collection of functions which provide direct access to the contents of the DVO database tables.

Schema

DVO uses the following database tables:

  • Sky Layout : defines the organization of the object / measurement tables on the sky
  • Photcodes : defines the photometric systems and transformations between them
  • Images : describes the images known the DVO; for a mosaic camera, one chip corresponds to a single image, and an additional meta-image is used to represent the full mosaic (note: these meta-images may soon be moved to a separate table; also note that the mosaic meta-image is only supplied for mosaic images with 'mosaic' astrometry solutions).
  • Average : average properties of the astronomical objects, excluding photometric average information (one row per object)
  • SecFilt : average photometric properties for astronomical objects (one row per 'average' filter per object).
  • Measure : all detections of the astronomical objects
  • Missing : non-detections of known astronomical objects nominally touched by an image (note : this table is not populated by default)

NOTE: the links for each table listed above point to the autocode description of the maximal schema table, a particular instance of a DVO database may use a reduced schema without all fields defined.

The standard implementation of DVO uses a stores the database information as a collection FITS tables. For a subset of the tables (Average, SecFilt?, Measure, Missing), the data is partitioned into multiple files representing different regions on the sky. The partitioning scheme allows for a wide range of scale on which the sky is divided. At one extreme, the entire sky is represented by a single file. At the next level, this is split into Declination bands of width 7.5 degrees. Next, these bands are split into RA ranges. The next levels subdivide the RA / DEC ranges into smaller and smaller patches. From the third level on down, the size of the sky regions varies with Galactic latitude to better sample regions of high and low stellar density.

more information on dvo databases:

DVO Shell

Working With DVO

  • Inserting Data (addstar)
  • DVO Keywords : A partially-completed list of keywords that can be used with "mextract" and "avextract"
  • Example CMD Script : An example DVO script that produces a color-magnitude diagram
  • Example Histogram Script : An example DVO script that produces a histogram
  • DVO Simtest Example : some simple examples using the Simtest reference database
  • DVO Database Tools : Programs for manipulating DVO database organization
  • DVO Parallel Operation : guideline to using DVO in a parallel mode
  • DVO Intro : introduction to the Desktop Virtual Observatory (on the CFHT elixir pages)
  • dvo.pdf manual from project documentation pages (needs updating, but describes concepts of dvo)

Examples and Details

Detailed Info on some features

Special Data in DVO

DVO Software Engineering

  • SDSS stripe82 data set For the daring, here is a 202 MB tarfile expanding into a 588 MB directory with a very small subset of multi-epoch (but not [yet] coadded) SDSS stripe 82 data at http://www.mpia.de/homes/jester/IPPstripe82_catdir_20080610.tgz The README describes what's there and how it was made. This is not (yet) useful for science! Email jester at mpia.de with questions regarding this dataset.