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Important information

The complete CASDA User Guide can be found at http://www.atnf.csiro.au/observers/data/casdaguide.html and covers alternate access methods such as Virtual Observatory tools and scripted/automated access.


Overview


This search facility allows users to search for Australian Square Kilometer Array Pathfinder (ASKAP) data taken from the facility in Western Australia.

CASDA Observation Search 


 Users can search using the following fields (see below for details):

Source Name / Position

Cone Search - Single Position

This section allows a cone search for a "Single Position" by either

  • Entering an object name
  • Manually entering the right ascension (RA ), declination (Dec) and a search radius

The following formats are supported

Format

Right Ascension (RA)

Declination (DEC)

Search Radius

 MINMAXMINMAXMINMAX
Decimal Degrees
(ddd.dddd)
0359.9999-90+90
N/A
Hours / Degrees Minutes Seconds
(HH:MM:SS.SSS / DD:MM:SS.SSS)
00:00:00.00023:59:59.999-90:00:00.00090:00:00.000N/A
Arc Minutes
(ddd.dddd)
N/AN/A1300

When conducting a cone search through the CASDA Observation Search, only image based data products will be returned. To conduct a cone search on catalogues, we recommend using Virtual Observatory tools. Refer to the CASDA User Guide for more details.

Cone Search- Multiple Positions

If you choose this option then you will be prompted to upload a file.

This file must be a text file with one position per line. Each line must contain J200 RA and Dec and an optional radius in arcmin with spaces between enteries.

Examples of acceptable formats are:

18:05:03.214 -26:02:05.23 1.0

18 05 03.214 -26 02 05.23 1.0

278.555  27.829  1.2

If using Internet Explorer, files containing up to 50 lines can be uploaded, for other browsers the limit is 100.

Observation / Project

Project

This is a type ahead field which is a combination of the project code and project title. The format of this field is Project code - Project title

Filename

This field can be used to search for data products by the filename.

Observation Scheduling Block ID Or Observation Date(UTC)

These fields allows a date range to be entered. Times are given in UTC+0 (or Greenwich Mean Time) rather than a local time. The search will return observations where the start time falls within the range specified.

Released versus Unreleased Data

Search can be performed for data that has been released to the public or data that is yet to be released. Only specified project users have access to unreleased data products.

Spectral Selection

Frequency Range

These fields allow for a frequency range to be entered.

Redshift

These fields allow a redshift range to be entered.

A Rest Frequency will also need to be selected from the drop down list, and only those data products that have such a Rest Frequency in their metadata will be returned.

Velocity

These fields allow a velocity range to be entered.

A Rest Frequency will also need to be selected from the drop down list, and only those data products that have such a Rest Frequency in their metadata will be returned.

Results Columns

The user can choose to show or hide each of these tabs in the search results.

  • Catalogue
  • Image cube
  • Spectrum
  • Visibility

CASDA Observation Search Results


CASDA search results page appears in the following format with the various types of results represented in tabs at the top:

Users will see the following message at the top of the search results page if they are not logged into the DAP:


Each tab contains search results for the particular data product type.

The following tabs may be available:

  • Catalogues: Lists catalogues matching your search criteria.

  • Image Cubes: Lists image cubes matching your search criteria.
  • Spectra: Lists image based data products matching your search criteria, such as spectra and moment maps.

  • Visibilities: Lists visibility files (Measurement Sets) matching your search criteria.

If there were no results for a given data product, the relevant tab will not be displayed.

The following Options are available on the search results page:

  • Refine search- This option returns the user to the CASDA Observation search  page with the search parameters retained from the previous search.

  • Filter results-  This option opens up in a popup window the filter facets that are available to further filter the search results on

  • Configure columns- For each of the search results tabs there will be default set of columns with metadata. This function allows users to customise which columns are displayed within each tab. 

The results columns within each tab can be configured by selecting the "Configure columns" option on the particular tab.

The Download button at the top will display a count of the number of files selected for download.


To retrieve data:

  1. Select the data you wish to access by marking the checkboxes next to the items you're interested in
  2. Some data types may allow you to choose a format
  3. Click on the "Download" button at the top to select a format and method


Catalogue Formats

On the "Catalogues" tab, there will be a dropdown box allowing you to select a format when accessing / downloading catalogue data.


File formats include:

  • CSV - Deliver the file(s) in "CSV" format, which can be opened in applications such as MS Excel.
  • VO Table - Deliver the file(s) in "VO Table" format, which can be used with VO clients such as Topcat.

Aggregation levels include:

  • Individual - A file will be prepared for each selected catalogue
  • Grouped - All catalogues of the same Catalogue Type will be grouped into a single file. That is, you will receive a file for each catalogue type.


Search Results fields

FieldExampleNotes
Selection box

Select these boxes to identify which items in the results you want to access or interact with.

Items which you cannot access (such as unreleased data products) will display a lock icon instead of a selection box.

You can select & deselect all checkboxes in a results tab by selecting / deselecting the checkbox in the results table column heading.

Scheduling Block ID

This is the Scheduling Block from which the data product was produced.
Project

This is the project that the data product belongs to.

By clicking the link, a user can view the project's Collection which contains that data product. The collection holds additional metadata about that project, such as the Principal Investigator, a list of Contributors and a description of the project.

A project may have more than one collection, typically two - one collection for catalogues and another for images, cubes & visibilities.

Num Entries

This column appears alongside catalogues to indicate how many records are present in the catalogue.
Data Quality

This field indicates the level of quality of a data product, as assessed by the project team. Poor quality data is still archived and made available, as it may be useful in certain contexts. The following are the possible quality states:

  • Good
  • Uncertain
  • Bad

Additional information about the quality level for a data product can be viewed by clicking on the quality level for that data product.

CASDA Image Generation Service


This service allows the users to define a cutout or spectrum of a region on interest.

Selected image details

The metadata associated with the selected image is displayed along with a preview of the image. To view larger image click on the "view larger image" link under the image preview.


New image parameter

The Aladin-Lite view displays a representation of the sky region from the Sydney University Molonglo Sky Survey (SUMSS). The red line marks the bounds of the image cube. Only area within the cutout can be selected.

The user can enter the J2000 range of values in the RA or Dec fields, and the Frequency values for Image Cube, to define a single cutout or spectrum.

The user can click and drag with the mouse to define an area in the Aladin-Lite view that is of interest to create a cutout or spectrum.


Create cutout

After selecting an area of interest, click on the "Create cutout" button to submit a job to create a cutout.


Create Spectrum

Note: A spectrum can only be generated where the image cube has multiple spectral channels.

CASDA Image Cube Summary


The metadata summary for an resultant object can be accessed by clicking on the  icon for that result.

This popup has a summary of the information about the selected file on the search results or the CASDA skymap search page.

The display depends on the type of data product. Below is an example of an image cube file.

Project Information

This section provides information about the project involved with the generation of the data file. 

Project NameName of the project responsible for the generation of the file
Project DescriptionA brief account of the aims and scope of the relevant project

Details

This section has information about the observation. The fields displayed depend on the data product.

Catalogues from the ASKAP Pipeline

Filename

The file name of the catalogue

SBIDs

The ID of the ASKAP scheduling block in which the observations were taken

Collection

The data collection which contains this data product
   - hyperlink to collection

Observation Start

Observation start time (yyyy-mm-ddThh:mm)

Observation End

Observation end time (yyyy-mm-ddThh:mm)

Download Evaluation Files

This includes all evaluation files and validation metrics.
Click the link to display the Retrieve Files page.

Derived Catalogues

Filename

The file name of the image

Collection

The data collection which contains this data product
   - hyperlink to collection

 

Image Cubes

Filename

The file name of the image

Type

The type of spectrum contained in the FITS file

SBIDs

The ID of the ASKAP scheduling block in which the observations were taken

Principal Investigator

The name of the principal investigator on the project

Collection

The data collection which contains this data product
   - hyperlink to collection

Observation Start

Observation start time (yyyy-mm-ddThh:mm)

Observation End

Observation end time (yyyy-mm-ddThh:mm)

Download Evaluation Files

This includes all evaluation files and validation metrics.
Click the link to display the Retrieve Files page.

 

Spectra

Filename

The file name of the image

Type

The type of spectrum contained in the FITS file

SBIDs

The ID of the ASKAP scheduling block in which the observations were taken

Image Cube

 Name of the Image Cube which the spectrum comes from

Object Name

ASKAP Object name of the source

Component ID

 

Principal Investigator

The name of the principal investigator on the project

Collection

The data collection which contains this data product
   - hyperlink to collection

Observation Start

Observation start time (yyyy-mm-ddThh:mm)

Observation End

Observation end time (yyyy-mm-ddThh:mm)

Centre Frequency

 

B Unit

 

B Type

 

Polarisation

The Polarisation(s) of this data product

Collection Type

Observational or Derived

Download Evaluation FilesThis includes all evaluation files and validation metrics.
Click the link to display the Retrieve Files page. 

Visibilities

Filename

The file name of the of the visibility

Collection

The   data collection which contains this data product
   - hyperlink to collection


Validation notes

Notes about specific aspects circumstance which may provide additional guidance have been added during the data validation process.


CASDA Image Cube Preview


Applicable for Image Cubes and Spectra

You must be logged in to have access to images.

A preview of the image will be displayed. There is also a link to open a larger version of the image.

Image Header

Applicable for Image Cubes and Spectra

This section displays the fields in the header and provides information about the processing history of the file.

Generate Image

Applicable for Image Cubes

When the current file is an image cube there is a ‘Generate Image’ button at the bottom of the popup. Clicking the button opens the CASDA Image Generation Service page where cutouts and spectra can be created.

CASDA Data Access and Download


Survey data products which have not been validated or publicly released can only be accessed by project team members in the DAP. Once validated and released all survey metadata will be accessible. Unauthenticated users can only access catalogue data although they will be able to view a list of all data product types. Logged in members will also have access to non-catalogue data (images, cubes, visibilities etc.).

Users can freely register an OPAL account to get authenticated access to data.

Please keep in mind that CASDA contains some very large files. The linked table provides best-case estimates of download times based on the size of the files.

There is a limit to how much data you can download at one time. Some browsers may also limit the size of downloads to around 2GB.

Access options include download via the web, or access within the Pawsey Supercomputing (PSC) facility. If you plan to access data within PSC, you will need to arrange access to the high performance compute facility. Please see Pawsey Supercomputing Centre user accounts for more information.

Accessing CASDA Files

CASDA data can be accessed by conducting a CASDA Observation Search and selecting files from the search results page, or by finding the DAP Collections containing the data and navigating to the collection's Data tab. You can find a collection by either conducting a DAP Search or opening a Project code link from the results page.

To access CASDA data:

  1. Select the checkboxes next to the items you're interested in
  2. Some data types may allow you to choose a format (see below)
  3. Choose your preferred retrieval method
  4. Select Retrieve files

  

A screen will then be displayed showing the status of your Data Access Request (see Retrieve Files below) and will provide details for accessing your data once it is ready.


Selecting the checkbox in the column heading will toggle selection of all files on all pages within the search results.

You may need to tell your browser to allow pop ups from the DAP to see this page display.

Data Access Request Status

Some CASDA data will take a long time to prepare. The Data Access Request Status page will show you the progress of your request. It will update every 30 seconds.

Copy or bookmark the URL to return to the page at a later time.


Once your data is ready, the page will provide the relevant details and links to download each file. A checksum file will also be made available for each requested data product.

To download the files you can either:

  • Select a link to download individual files
  • Select Save links as text file to download a text file containing all the links to files
  • Select Download tar to download all files in a TAR file

Data access jobs will expire after a set time to allow space to be cleared for other users. The status page will provide your job's expiry details.

CASDA Checksums

CASDA provides checksums for catalogue data, images and visibilities. The checksums can be used to ensure that the data files were downloaded correctly.

Please download and use the attached scripts to calculate checksums and verify checksums.



Need help with the Data Access Portal? Please contact Research Data Service Support at researchdatasupport@csiro.au or phone: +61 2 4960 6086

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