|All-Sky Automated Survey for Supernovae|
We are taking data with our two CTIO-based "Cassius" telescopes! (May 2014)
We are taking and reducing in real time data with four telescopes in Hawaii (Dec. 2013).
What is ASAS-SN?
The sky is big: even in the present day, only human eyes fully survey the sky for the transient, variable and violent events that are crucial probes of the nature and physics of our Universe. We plan to change that with our "All-Sky Automated Survey for Supernovae" (ASAS-SN or "Assassin") project, which will (eventually) automatically survey the entire visible sky every night down to about 17th magnitude, more than 10,000 times deeper than human eye. Such a project is guaranteed to result in many important discoveries, some of them potentially transformative to the field of astrophysics.
ASAS-SN is currently comprised of two units. ASAS-SN Unit-1, known as "Brutus", which also happens to be the name of the Ohio State mascot, is comprised of four robotic 14-cm telescopes deployed at the Haleakala station of the Las Cumbres Observatory Global Telescope Network. ASAS-SN Unit-2, named "Cassius", consists of two 14-cm telescopes deployed at the LCOGT Cerro Tololo station. Together, these allow us to observe a total of approximately 15,000 square degrees each clear night. Eventually we would like to deploy a total of 16 telescopes at four different sites, allowing us to survey the entire visible sky every night. We started real-time reduction and analysis of "Brutus" four-telescope data in December 2013 and are continuing to make interesting discoveries. In addition, the "Cassius" two-telescope system is now making discoveries as well.
We are discovering numerous supernovae in both hemispheres (38 so far, 9 in June and 11 in May 2014).
Here are some of our most exciting objects:
ASASSN-14dc (June 2014). SN in 2MASX J02183825+3336556. V=15.8, our furthest away and most luminous supernova so far (about 200 Mpc away, M_V=-20.6).
ASASSN-14be (May 2014). Extreme (delta V>6.6 mag) M-dwarf flare.
ASASSN-14ae (January 2014). A Tidal Disruption Event (TDE) in SDSS J110840.11+340552.2 (z=0.04367). Discovered right near our limit of V=17.0, about 200 Mpc away, this is the closest TDE candidate ever discovered in optical wavelengths.
ASASSN-13dn (December 2013). SN Type II in SDSS J125258.03+322444.3. V=15.7, about 100 Mpc away. This was only our second non-Type Ia supernova, out of 15 discovered at that point, and at absolute V magnitude of approx. -19.3 it is very luminous.
We started real-time reduction and analysis of "Brutus" two-telescope data in April 2013 and we had a number of exciting discoveries:
ASASSN-13cb (August 2013). Extreme (delta V~9 mag) M-dwarf Flare.
AGN Outburst and Dramatic Seyfert Type Change in NGC 2617 (April/May 2013). See also ATel #5103, #5059 and #5039.
Generally we are posting our real-time discoveries using ATel, so if you interested in being notified of our results, you should subscribe to that useful service, and also see our ASAS-SN Transients page.
We are not yet fully "All-Sky", but we are getting there, see below where our supernova discoveries announced so far are located on the sky:
José Luis Prieto (Universidad Diego Portales);
Joseph Brimacombe (Coral Towers Observatory);
David Bersier (LJMU).
We thank LCOGT and its staff for their continued support of ASAS-SN, especially M. Dubberley, M. Elphick, S. Foale, E. Hawkins, D. Mullens, A. Pickles, W. Rosing, R. Ross and Z. Walker.
A crucial part of our project is the follow-up effort with bigger telescopes to get confirmation imaging (Brutus has 7.5" pixels) and spectroscopy. Sometimes a space-based telescope is needed: outburst of the AGN in NGC 2617 has been monitored by Swift. A number of people have kindly contributed their own telescope time to help us in our effort, which we most appreciate! Here are the names of our collaborators on ASAS-SN results annouced so far: S. Adams (Ohio State), A. Campillay (Las Campanas Observatory), C. Choi (Seoul National University), C. Contreras (Las Campanas Observatory), C. Copperwheat (LJMU), G. De Rosa (Ohio State), M. Dietrich (Ohio University), M. Fausnaugh (Ohio State), D. Grupe (Penn State), D. Gifford (University of Michigan), M. Giustini (XMM-Newton Science Operation Centre), C. Gonzalez (Las Campanas Observatory), A. Goulding (CfA), K. Hainline (Dartmouth), D. Hartmann (Clemson), R. Hickox (Dartmouth), R. Hounsell (STScI), D. Howell (LCOGT), E. Hsiao (Las Campanas Observatory), M. Im (Seoul National University), A. Kaur (Clemson), S. Komossa (Max-Planck Institut fur Radioastronomie), M. Koss (IfA), P. Lira (U. Chile), K. Leighly (University of Oklahoma), S. Mathur (Ohio Sate), N. Morrell (LCO), A. Mosquera (Ohio State), D. Mudd (Ohio State), J. Nugent (University of Oklahoma), B. Peterson (Ohio State), M. Phillips (Carnegie Observatories), R. Pogge (Ohio State), A. Porter (Clemson), J. Rich (Carnegie Observatories), D. Sand (Texas Tech University), S. Schmidt (Ohio State), A. Sheffield (Columbia), S. Starrfield (ASU), M. Wagner (LBTO), A. Wilber (ASU), C. Woodward (U. Minnesota), S. Valenti (LCOGT), S. Villanueva (Ohio State), Y. Yoon (Seoul National University), Y. Zu (Carnegie Mellon).
So when you get an e-mail or a phone-call from us, asking to collaborate on a new exciting ASAS-SN target, we hope you will say "yes"!
Our team makes ASAS-SN a success, but we also need excellent hardware to aid us in our ultimate goal of studying real-time variability of the entire sky:
To achieve large field of view with a very stable and uniform point-spread-function (PSF) across the field, we use Nikon AF-S NIKKOR 400mm f/2.8G ED VR AF lenses. We had high expectations for these lenses and were not disappointed: we obtain very stable and sharp images for many nights in a row. This is crucial for the image subtraction method, which we employ to detect transients, to work best.
Since we are using relatively small telescopes (lenses), we cannnot afford to waste many photons. As our detectors we have selected ProLine PL230 CCD cameras from FLI, with back-iluminated E2V sensors, giving us high QE, low-noise and fast readout (and of course they are electrically cooled). To cover several thousand square degrees each night, we take many hundreds of images nightly, and we have been very happy with the reliability of our cameras.
If you think monitoring the Variable Universe is a good idea and you would like to donate to that cause, please contact us.