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Data Quality Control (DQC) Interface

All the processed INT WFS data is now available through a PostgreSQL database derived from an ingest of the FITS header contents including the derived data quality control information. Data cutouts, image catalogues, science images and much more are available through this access point. A registration script is built into the browser for those who wish to access all the facilities offered therein.

FITS header information, including QC parameters, are ingested on a regular basis, and a series of flat files point to the processed object catalogues and image data. This has allowed us to offer optional further processing stages driven from a survey Quality Control database.

The database interface supports a large range of user options including: on-the-fly multipassband merging of catalogue data and optional federation with other catalogues such as FIRST and 2MASS; production of target postage-stamps for candidate selection or for making finding charts; interactive interrogative catalogue overlays on images; uploading of lists of target objects; automatic retrieval and downloading of catalogue and image products; the ability to group and remotely process images using CASU facilities including the CASU VDFS (Vista Data Flow System) image subtraction, image stacking and image mosaicing software utilities and retrieval of the results etc.

Go the DQC Interface

Example use of the DQC interface

This example will show some of the characteristics of the DQC interface while searching for observations of a particular object. The following screenshots show how to query the database for images in a particular set of filters and preview the images and catalogues before downloading the data. Throughout all the real process a link to a help page provides extensive documentation on how to use each form.

The DQC page provides a wide range of options to search for images. In this example we look for one particular object in the U,g,r,i and Z bands.

After submitting the search we are presented with a table of fields that satisfy the query. The fields with the search point on the CCD are automatically selected. This table provides for each of the fields with information about the airmass, exposure time, seeing, limiting magnitude, etc.

In the same page we are given several options for preview and data retrieval. We can preview cutouts of the selected images around the object, mosaics of all the CCDs in each pointing or the individual CCDs. Finally we can select no preview and go directly to the data retrieval.

These are examples of cutouts of the selected object. It is possible to overlay different catalogues as well (right). All the cutouts can be saved in a single postscript or png file as in here and here.

Examples of mosaic and single CCD image previews.

Several options for catalogue retrieval are presented (Note: You need to log in to have access to the catalogues).

Finally the selected images and catalogues can be downloaded as single images, mosaiced or even stacked. Options to substract images are also available.