This supernova exploded on March 15, 2005. I observed it every night during my stay at La Silla.
Its host galaxy, NGC 6744, lies at a distance of 32 million lightyears, and hence its stars are much too far away to be resolved in the image.
All the white dots are stars in our own Galaxy, the Milky Way. Except the one at the end of the green arrow — that's SN 2005at.
Together with data from the Hubble and Spitzer Space Telescopes, it was interesting enough to write an article about (Kankare et al. 2014).