The SkyMapper Transient (SMT) survey is performing a rolling search of the southern and equatorial sky utilizing the SkyMapper Telescope. The search footprint is covering approximately 2000deg2 with an expected cadence of 3-4 nights.

As one of the flagship missions of the ARC Centre for Excellence in All- Sky Astrophysics(CAASTRO), SkyMapper transients will contribute signicantly to the study of both the Dynamic Universe and the Dark Universe. While most of the SkyMapper discoveries will be Type Ia supernovae (SNe Ia) useful for probing Dark Energy, the remainder of these dynamic events will probe the diversity of explosions throughout the Universe.

Our main goal is to obtain an untargeted sample of SNe Ia at redshifts below 0.1 to improve the low-z Hubble diagram anchor and to study peculiar velocities. Also, we are interested on studying SNe environments, their progenitors and peculiar transients.

SkyMapper started recently to search and follow-up supernovae in the Southern Sky. We are continually improving search operations to deliver quality SN Ia lightcurves. Aside from SNe Ia, we have a program to search for optical counterparts to interesting astrophysical transients such as Gravitational Waves, Fast Radio Bursts, and others.

How do we discover supernovae
Supernovae are "transient events", they shine very brightly for weeks and then fade away. A good way of finding transient objects in the sky is to compare an "old" or "reference" image to a "new" image. If a bright object appears on the "new" image which was not a month ago we have found a transient event! Usually we call this process subtraction, which is literally subtracting the new image from the old, so if you have a star or a galaxy in the "new" and "old" image they will be no event in the "subtracted" image.

Our detailed pipeline which includes a parallelised software pipeline to discover variable objects in difference imaging using machine learning can be found in our recent work The SkyMapper Transient Survey, Scalzo et al. 2017.

photo:James Gilbert

The SkyMapper telescope
The SkyMapper telescope was constructed by EOS Australia. It has a modified cassegrain design, featuring:

  • A 1.35m primary mirror
  • A 0.71m secondary (on 5 axis hexapod mount)
  • A 0.56m aspheric corrector
  • Two additional spherical correcting elements
All transmissive optics are made of fused silica to ensure optimal UV throughput. The telescope is housed in a dome that is 11.5m tall and 6.25m in diameter. The facility is located near the summit of Siding Spring Mountain, at The Australian National University's Siding Spring Observatory.

The SkyMapper Southern Sky Survey Early Data Release is already available for Australia with Image Cutouts and Data Access.