All-Sky Automated Survey for Supernovae
NEWS: We have discovered ASASSN-15az, our 100th supernova! (January 2015).
ASAS-SN results presented at the AAS press conference (January 2015).
With funds from Mt. Cuba Astronomical Foundation Cassius will become a four-telescope unit! (December 2014)
ASASSN-14lp, currently the brightest SN on the sky, will be monitored by HST! (December 2014)
ASASSN-14li, TDE candidate only 90 MPc away! (December 2014)
See our ASASSN-14ae press release (October 2014).
We are finding about half of the brightest (<17th mag) supernovae (October 2014).
We have now discovered 50 supernovae! (August 2014)
Our first supernova discovered with "Cassius"! (June 2014)
We are taking data with our two CTIO-based "Cassius" telescopes (May 2014).

ASAS-SN: Transients | Supernovae | CV Patrol | ATels | Papers

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

Our telescopes are hosted by .

ASAS-SN is supported in part by and

If you think monitoring the Variable Universe is a great idea and you would like to donate to that cause, please contact us.

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 25,000 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---think about ASAS-SN as the "SSST" - Small Synoptic Survey Telescope, complementing LSST and other time-domain projects by frequently observing the entire bright sky. Bright transients, Galactic and extragalactic, discovered early by our high-cadence survey, are especially valuable, as they are easy to study using relatively modest size telescopes.

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, and will soon (June 2015) be expanded to four telescopes as well.

We are discovering numerous bright supernovae in both hemispheres (131 so far, 114 since May 1st, 2014).

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

Here are some of our most exciting objects:

ASASSN-15az (January 2015). Type Ia supernova, V=16.7, about 125 Mpc away. Our 100th supernova!

ASASSN-15ab (January 2015). Type IIn supernova, V=16.4, about 80 Mpc away. First ASAS-SN supernova announced in 2015, our 92nd SN overall.

ASASSN-14lv (December 2014). Faint SN candidate, V=17.2, about 200 Mpc away. The furthest SN discovered by ASAS-SN to date.

ASASSN-14lp (December 2014). SN Type Ia. V=13.0, about 18 Mpc away. Our brightest supernova so far!

ASASSN-14li (December 2014). A Tidal Disruption Event (TDE) in PGC 043234 (z=0.0206). About 90 Mpc away, this is the closest TDE candidate ever discovered in optical wavelengths, half the distance of ASASSN-14ae.

ASASSN-14kq (November 2014). SN Type Ia. V=16.8, about 140 Mpc away. Our 75th supernova!

ASASSN-14ha (September 2014). SN Type II in NGC 1566. V=14.6; our closest supernova so far at about 20 Mpc away.

ASASSN-14fj (August 2014). SN Type II in NGC 5732. V=16.8, about 53.9 Mpc away. Our 50th supernova!

ASASSN-14fd (August 2014). SN Type IIn in PGC 043470. V=16.6, about 67.9 Mpc away. Has brightened up to V~15.1 since discovery.

ASASSN-14eu (August 2014). SN Type Ia-pec in PGC 053612. V=16.6, about 97.9 Mpc away. 50.5 arcseconds (projected distance ~24 kpc) from the core of its host galaxy.

ASASSN-14dd (Cassius discovery, June 2014). SN Type Ibn in NGC 2466. V=15.6, about 75 Mpc away.

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-14db (Cassius discovery, June 2014). Luminous SN Type I in ESO 075-G049. V=16.3, about 158 Mpc away.

ASASSN-14cu (Cassius discovery, June 2014). SN Type Ia in 2MASX_J12470274-2414435. V=16.2, about 108 Mpc away. The first supernova discovered with our Cassius unit!

ASASSN-14co (June 2014). SN Type Ia in PGC 056486. V=16.9, about 142 Mpc away. Our 30th supernova!

ASASSN-14cl (June 2014). A very large amplitude CV outburst that has been observed more than 20,000 times!

ASASSN-14az (May 2014). Bright SN Type IIb in GALEXASC J234448.27-020653.4. Our brightest SN (at discovery) with V=14.5, about 23 Mpc away.

ASASSN-14ax (May 2014). SN Type Ia in SDSS J171000.70+270619.6. V=16.5, about 140 Mpc away. Our 20th supernova!

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.

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-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-13cc (August 2013). SN Type Ia, 40 Mpc away in NGC 1954.

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

ASASSN-13bb (July 2013). SN Type Ia, our 2013 July 4th supernova.

ASASSN-13av (June 2013). SN Type Ia. Our third supernova!

ASASSN-13ar (June 2013). SN Type Ia. Our second supernova!

ASASSN-13an (June 2013). SN Type Ia. Our second supernova!

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

and here we show which parts of the sky have been observed recently (avoding the Sun and the Moon)

At this point we are focused on discovering bright, nearby supernovae, but we like all kinds of variable objects, so if there is an object with V-band magnitude between V~9 and V~17 that we might have in our data, send us an e-mail and we will check what we have.


At OSU: Bianca Danilet, Tom Holoien, Chris Kochanek, Kris Stanek, Greg Simonian, Udit Basu (high school student), Noah Goss (high school student), John Beacom, Todd Thompson;

Ben Shappee has moved (August 2014) to Carnegie Observatories, Pasadena, to start his 5-year Hubble-Carnegie-Princeton Postdoctoral Fellowship;

José Luis Prieto (Universidad Diego Portales; MAS);

At Warsaw University Observatory: Grzegorz Pojmanski, Dorota Szczygiel;

Joseph Brimacombe (Coral Towers Observatory);

David Bersier (LJMU);

Subo Dong (KIAA-PKU);

Emilio Falco (CfA);

Przemek Wozniak (LANL).

Jacob Jencson has finished his undegraduate education at OSU and has moved to astronomy graduate program at Caltech. Good luck, Jacob!

We thank LCOGT and its staff (including M. Dubberley, M. Elphick, S. Foale, E. Hawkins, D. Mullens, W. Rosing, R. Ross and Z. Walker) for their continued support of ASAS-SN.

An important part of our project is the follow-up effort with bigger telescopes to get confirmation imaging (our images have 7.8" pixels). We are fortunate to have a number of "professional amateur astronomers" working with us on ASAS-SN "ad hoc" SN confirmation effort: E. Conseil (Association Francaise des Observateurs d'Etoiles Variables), I. Cruz (Cruz Observatory, Ohio), J. Hissong (Columbus Astronomical Society, Ohio), S. Kiyota (Variable Star Observers League in Japan), R. A. Koff (Antelope Hills Observatory), L. A. G. Monard (Klein Karoo Observatory, Western Cape, South Africa), B. Nicholls (Mt. Vernon Obs., New Zealand), J. Nicolas (Groupe SNAUDE, France) and W. Wiethoff (University of Minnesota, Duluth). You can see from many joint Astronomer's Telegrams we have already published that it is quickly becoming a very fruitful collaboration!

A number of professional astronomers have also contributed their effort and telescope time to ASAS-SN, which we most appreciate! Here are the names of our collaborators on ASAS-SN results annouced so far: S. Adams (Ohio State), E. Alper (Dartmouth), 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), S. Dong (KIAA), M. Fausnaugh (Ohio State), J. Fernandez (Pontificia Universidad Catolica), D. Grupe (Penn State), D. Gifford (University of Michigan), M. Giustini (XMM-Newton Science Operation Centre), C. Gonzalez (Las Campanas Observatory), A. Goulding (CfA), Z. Guo (KIAA), K. Hainline (Dartmouth), D. Hartmann (Clemson), G. Herczeg (KIAA), R. Hickox (Dartmouth), R. Hounsell (STScI), D. Howell (LCOGT), E. Hsiao (Las Campanas Observatory), M. Im (Seoul National University), J. Jose (KIAA), 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), J. Thorstensen (Dartmouth), 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) (if we missed your name, please let us know).

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:

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 15,000 thousand square degrees each night, we take several hundreds of images nightly with each camera, and we have been very happy with the reliability of our cameras.

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.

We thank George Skestos for his generous gift to Prof. Kochanek, which was partially used to support ASAS-SN.

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

This homepage is maintained by Tom Holoien and Kris Stanek. Updated Sun Jan 18 15:38:39 EST 2015
eXTReMe Tracker