ASKAP Observation Search

Overview

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.

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

ASKAP Observation Search

The ASKAP Observation search is making data from Australia’s SKA Pathfinder (ASKAP) telescope available to the astronomical community.

Search button

Users can find data by either choosing the ‘Search’ button to get all results or by using the following fields to narrow the search results to an area of interest:

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
	MIN	MAX	MIN	MAX	MIN	MAX
Decimal Degrees (ddd.dddd)	0	359.9999	-90	+90	N/A
Hours / Degrees Minutes Seconds (HH:MM:SS.SSS / DD:MM:SS.SSS)	00:00:00.000	23:59:59.999	-90:00:00.000	90:00:00.000	N/A
Arc Minutes (ddd.dddd)	N/A		N/A		1	300

When conducting a cone search through the ASKAP 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

Examples for project code include:

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.

ASKAP Observation Search Results

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

The ASKAP search results are returned in a table format, which are found in 5 tabs: "Catalogue", "Image cubes", "Spectra", "Visibilities", "Ancillary"

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

Message text: "You must sign in to access image based data products"

Search parameters

The search parameters you selected are displayed at the top of the page. Parameters with a ‘x’ can be deleted to refresh the search.

Data product tabs

Each tab contains search results for a particular data product type:

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.
Ancillary: Lists ancillary data products matching your search criteria.

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

Filters

Filter facets that are available to further refine the search results.

Buttons

The following buttons are available on the search results page:

Refine search – This button returns the user to the ASKAP Observation search page with the search parameters retained from the previous search.
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 by clicking “Configure columns” on the particular tab.

Download

To retrieve data

Select the data you wish to access by marking the checkboxes next to the items you’re interested in.
The Download button at the top will display a count of the number of files selected for download.
Some data types may allow you to choose a format.
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

Field	Example	Notes
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.

CARTA visualisation

(Beta release October 2023)

The release of CARTA visualisation tool for CASDA is a Beta release.

We want to know about your experience with CARTA:
– what worked, what didn’t, what improvements are needed.
Please send feedback and support requests to atnf-datasup@csiro.au

Connecting to CARTA – Step by step

Sign into ASKAP Observational Search
1. Select your parameters
2. Click the “Search” button
Download the file/s
1. For a single file:
  1. Click on the CARTA icon next to the file you want to select
  2. A pop up window will appear listing the file name you selected. Click the “Submit” button
2. For multiple files:
  1. Click the checkboxes for each file you want to select (files must be in the same search)
  2. Click the “Download” button
  3. In the “Select a method” drop down menu, select “View in Carta”
  4. Click the “Request files” button

Check the licence conditions
1. Read through the licence conditions and check the checkbox if you agree to the terms
2. Click the “Accept” button (if data is still cached, this is not displayed)
Data download for CARTA
1. The Download Job status bar displays ‘Preparing date for retrieval’ (yellow) while your data is downloading.
2. The Download Job status bar displays ‘Your data is ready for CARTA visualisation’ (green) when your data download is complete.
3. The data will be available for x days. Bookmark the link so you can return to use the same data within this period.
Request CARTA session
1. When the download job is completed you can start the CARTA session. The CARTA Session status bar displays ‘Session Queued’ (blue) until the session is available.
2. Click the ‘Request CASDA CARTA Session’ button.
CARTA session has been started
1. The CARTA session is ready for your use when the status bar changes to ‘Session available’ (green)
2. Click ‘Connect to CASDA CARTA Session’ button
3. The session will last 3 hours
4. The session should only be used by one person at a time
5. Up to 10 sessions can be active at one time
6. As this is a Beta implementation these parameters may change depending on feedback
In CARTA session
1. Select the file you want to use
2. Click the ‘Load’ button
File loaded in CARTA
1. File can now be used in CARTA.
2. The session will last for 3 hours.
3. Note: Chrome has a feature to suspend a tab if it has been inactive for 30 minutes. This will cancel your CARTA session.

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 Name	Name of the project responsible for the generation of the file
Project Description	A 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. CASDA provides checksums for all files. The checksums can be used to ensure that the data files were downloaded correctly.

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. CASDA provides checksums for all files. The checksums can be used to ensure that the data files were downloaded correctly.

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 Files	This includes all evaluation files and validation metrics.CASDA provides checksums for all files. The checksums can be used to ensure that the data files were downloaded correctly.

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 created by the Science Survey team about the data release including considerations relating to the data quality.

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.

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 ASKAP 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:

Select the checkboxes next to the items you’re interested in
Some data types may allow you to choose a format (see below)
Choose your preferred retrieval method
Select Request files

Note: ‘View in CARTA’ only available for images

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.

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 all files. 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.