Thanks, for this. As a general comment, a closer. larger image of the moth would help with ID if possible however. There are similar looking species of this genus possible in the ACT, so it cannot always be presumed its S. plana.
Seeing the hindwings would be diagnostic too. But this forewing pattern looks unique among the 29 on the BOLD Synemon page http://v4.boldsystems.org/index.php/TaxBrowser_Taxonpage?taxid=86484