All-Sky Automated Survey for Supernovae
Our telescopes are hosted by . ASAS-SN is supported in part by

NEWS: "Cassius" is deployed in Chile! (April 2014)
"Brutus" is taking data with four telescopes in Hawaii, and we now started real time reduction (Dec. 2013).

ASAS-SN Transients | APOW: Picture of the Week | Channel | Twitter | ASAS (Warsaw)

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.

At this point we have two four robotic 14-cm telescopes deployed at Haleakala station of the Las Cumbres Observatory Global Telescope Network, each with a 4.5x4.5 degrees field of view, allowing us to observe approximately 5,000 10,000 square degrees each clear night. These four telescopes form Unit-1 of ASAS-SN, known as "Brutus", which also happens to be the name of the Ohio State mascot. ASAS-SN Unit-2, named "Cassius", will be deployed in the Southern Hemisphere in 2014, initially with two telescopes, allowing us to improve our cadence and sky coverage. Eventually (donations welcome!), we would like to deploy 10 more telescopes and cameras at four different sites, allowing us to automatically survey the entire visible sky every night.

We started real-time reduction and analysis of "Brutus" four-telescope data in December 2013 and we are already making interesting discoveries:

We continue to discover numerous bright cataclysmic variables, many of which are being intensely observed by professional and amateurs astronomers.

ASASSN-14ae (January 2014). Very luminous and blue SN Type II in SDSS J110840.11+340552.2 (z=0.04367). Discovered right near our limit of V=17.0, about 180 Mpc away, by far our furthest supernova discovery. This is only our third non-Type Ia supernova, and it is a very unusual event: while a young Type II SN seems the most likely interpretation, the proximity to the galactic nucleus makes a tidal capture transient a potential alternative.

ASASSN-14ad (January 2014). SN Type Ia in SDSS J124011.38+180341.9. V=16.8, about 110 Mpc away.

ASASSN-13dn (December 2013). SN Type II in SDSS J125258.03+322444.3. V=15.7, about 100 Mpc away. This is only our second non-Type Ia supernova, out of 15 discovered so far, and at absolute V magnitude of approx. -19.3 it is very luminous.

ASASSN-13dm (December 2013). SN Type Ia in PGC 2816341. V=15.9, about 70 Mpc away. The first ASAS-SN supernova found using four-telescope configuration.

We started real-time reduction and analysis of "Brutus" two-telescope data in April 2013 and we had a number of exciting discoveries:

ASASSN-13dl (October 2013). SN Type Ia in Uncatalogued Galaxy. V=16.8, about 120 Mpc away.

ASASSN-13dd (September 2013). SN Type Ia. V=15.2, about 50 Mpc away.

ASASSN-13cu (September 2013). SN Type Ia. Our faintest SN yet, V=17.0, about 110 Mpc away.

ASASSN-13cp (August 2013). SN Type Ia. Our 10th supernova!

ASASSN-13co (August 2013). SN Type IIP. Our first non-Ia supernova, about 90 Mpc away!

ASASSN-13ck (August 2013). Large amplitude outburst (8 magnitudes) cataclysmic variable.

ASASSN-13cj (August 2013). SN Type Ia.

ASASSN-13ch (August 2013). SN Type Ia.

ASASSN-13cc (SN 2013ex) in NGC 1954 (August 2013). SN Type Ia, our closest supernova so far, 40 Mpc away.

ASASSN-13cb: Extreme (delta V~9 mag) M-dwarf Flare (August 2013).

ASASSN-13bb (SN 2013ef): Our 2013 July 4th supernova. SN Type Ia, see ATel #5194.

ASASSN-13aw (SN 2013dr): Our fourth supernova (July 2013). SN Type Ia, was also discovered independently by another group.

ASASSN-13av (SN 2013ei): Our third supernova (June 2013). SN Type Ia, see ATel #5181.

ASASSN-13ar (SN 2013dl): Our second supernova! (June 2013) SN Type Ia, see ATel #5155.

ASASSN-13an (SN 2013da): Our first supernova! (June 2013) SN Type Ia.

AGN Outburst and Dramatic Seyfert Type Change in NGC 2617; see also ATel #5103, #5059 and #5039 (April/May 2013)

We have also discovered a number of bright Cataclysmic Variables, see ATel #4987, #4999, #5052, #5082, #5102, #5118, #5168, #5186, #5195.

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 discoveries announced so far are located on the sky:

At this point we are focused on discovering nearby supernovae, but we like all kinds of variable objects, so if there is an object with V-band magnitude between V~10 and V~17 that we might have in our data, send us an e-mail and we will check what we have. This procedure will be more automated in the near future, stay tuned!


At OSU: Ben Shappee, Chris Kochanek, Kris Stanek, Tom Holoien, Jacob Jencson, Udit Basu (high school student), Bianca Danilet, John Beacom;

José Luis Prieto (Princeton);

At Warsaw University Observatory: Grzegorz Pojmanski, Dorota Szczygiel;

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), R. Hickox (Dartmouth), R. Hounsell (STScI), D. Howell (LCOGT), E. Hsiao (Las Campanas Observatory), M. Im (Seoul National University), 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), J. Rich (Carnegie Observatories), D. Sand (Texas Tech University), S. Schmidt (Ohio State), A. Sheffield (Columbia), S. Starrfield (ASU), M. Wagner (LBTO), E. Woodward (U. Minnesota), S. Valenti (LCOGT), S. Villanueva (Ohio State), Y. Yoon (Seoul National University), Y. Zu (Pittsburgh).

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"!

ASAS-SN Hardware:

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.

This material is based upon work supported by the National Science Foundation under Grant number AST-0909916 (2009-2013).

This homepage is maintained by Ben Shappee and Kris Stanek. Updated Sun Mar 30 14:45:59 EDT 2014
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