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11th of May 2020
GASKAP imaging of the SMC
The Small Magellanic Cloud (SMC) is a satellite galaxy of the Milky Way. The GASKAP team have recently used ASKAP to image the SMC over 12 hours in a newly available "zoom" mode, which provides a higher spectral resolution and allows us to step through the neutral hydrogen content of the SMC in smaller increments than ever before. The image above is one frame of a full animation of a data cube, which consists of two spatial dimensions (the 2D image in each frame) and one spectral dimension (each frame being a different radio frequency channel). The densest regions of neutral hydrogen correspond to the brightest yellow in each frame. By measuring the brightness and distribution of gas in each channel, we can build a 3D picture.

As the observed neutral hydrogen extends over ASKAP’s entire field of view, the GASKAP teasm had to apply a unique method of processing to these data. Typical ASKAP fields are produced by stitching together images from individual beams. In the case of the SMC, this risked losing important structure that extends over the boundaries of multiple beams during this stitching stage. To avoid this, Nick Pingel wrote a custom imaging pipeline that utilizes the Common Astronomy Software Applications (CASA) package to stitch all of the ASKAP beams together before progressing on to further processing stages, including folding in some single-dish data from Parkes. The GASKAP team then used Swinburne University’s OzStar supercomputer to process the full data set and construct the image cube. The small incremental steps shown in the animation provide novel insight into how the SMC rotates and interacts with our own Milky Way.

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