SkyMapper

The SkyMapper ASVO node is the primary access point to the SkyMapper data. The first version of the node was co-developed by the National Computing Infrastructure (NCI), Australian National University (ANU), and Intersect Australia Limited. The node has three major data releases:

• Construct observer light-cones from the simulated data cube;
• Generate complete spectral energy distributions for model galaxies to provide multi-wavelength coverage;
• Produce mock images of the sky in each simulated universe;
• Select from preset “virtual telescopes” that make reconstructing existing surveys easy.

It uses a cloud-based architecture that offers Infrastructure as a service (IaaS), Data as a service (DaaS), and Software as a service (SaaS). It is configured in such a way that additional modules can be built and easily inserted into the data chain as needs require in the future. Refer to Bernyk et al., The Astrophysical Journal Supplement Series 223.1 (2016) for additional details.

• Test Data Release (TDR) – July 2015

The Test Data Release was a preview of the Survey data, designed to show their characteristics, while also testing data access methods for images and catalogues. It covers approximately 60 square degrees near RA=13h 40m and Dec=-15 deg.

• Early Data Release (EDR) – May 2016

The Early Data Release provided data from the Short Survey across one-third of the southern sky. EDR includes all fields observed between March 2014 and March 2015 where at least two visits of the telescope were made in near-photometric conditions. Each visit includes an exposure in all six filters, uvgriz.

• First Data Release (DR1) – June 2017

The First Data Release provides data from the Shallow Survey across >98% of the southern sky, mostly covering the range from the South Celestial Pole to +2 deg in declination, with some extra coverage reaching +10 deg. DR1 includes fields observed between March 2014 and September 2015, with a number of quality cuts applied. Additionally, DR1 includes measurements from over 2.3 billion detections covering over 20,200 deg2 of the sky. They correspond to ~300 million unique astrophysical objects from magnitude 8 to 18 (complete to ~17.5 mag, depending on the filter).

Data is currently accessible through Virtual Observatory-compatible tools such as TOPCAT, and Aladin. The system supports the following VO Services:

• Cone Search(including SCS)
• Image Cutouts(including SIAP)
• Full Catalogue Search(including TAP access)

More details are available on the data access page. An alternative web-interface is provided as well.

Technology currently used:

• Python Django
• Python CherryPy
• Basic JavaScript using JQuery and D3JS.

Hardware arrangement:

Currently the node is hosted on a virtualized instance at the National Computing Infrastructure (NCI).

• Database Server (8 CPUs, 32 GB).
• Virtual Node for the user interface hosting (2 CPU, and 8 GB).
• Storage is provided by NCI. For the early data release: 1.8 TB of table data (stored on an NCI virtual machine) and 19TB of compressed images (50TB uncompressed equivalent – stored on NCI’s g/data1 system). The node is expecting a data growth to approximately 8TB of table data and up to 200TB of images by the end of 2017.