All-Sky Automated Survey for Supernovae

All-Sky Automated Survey for Supernovae
Name	All-Sky Automated Survey for Supernovae
Acronym	ASAS-SN
Organization	Ohio State University; Las Cumbres Observatory
Established	2013
Location	Haleakala Observatory; Cerro Tololo Inter-American Observatory; Sutherland Observatory
Wavelength	Optical
Telescope type	Network of small telescopes

All-Sky Automated Survey for Supernovae is a networked wide-field transient survey designed to discover bright supernovae and transient phenomena across the entire night sky. The project operates automated telescopes located at multiple observatories and collaborates with institutions and facilities to provide rapid identification, classification, and follow-up of transient candidates. ASAS-SN has contributed to time-domain astronomy through systematic all-sky monitoring, rapid alerts, and public data releases.

Overview

ASAS-SN was conceived to perform continuous wide-field monitoring with instruments distributed among observatories such as Haleakala Observatory, Cerro Tololo Inter-American Observatory, and Sutherland Observatory while interfacing with institutions like Ohio State University, Las Cumbres Observatory, Harvard-Smithsonian Center for Astrophysics, NASA, and various university groups. The survey emphasizes discovery of nearby Type Ia supernovae, Type II supernovae, and other explosive transients including tidal disruption events, kilonovae, and unusual eruptive variables, enabling follow-up by facilities such as Keck Observatory, Very Large Telescope, Gemini Observatory, Subaru Telescope, and networks like Global Relay of Observatories Watching Transients Happen.

History and Development

The project was initiated by teams led at institutions including Ohio State University and grew through partnerships with observatories in the United States, Chile, and South Africa, building on precedents set by surveys such as Palomar Transient Factory, Catalina Sky Survey, Zwicky Transient Facility, Pan-STARRS, and historical efforts like Harvard College Observatory patrols. Early upgrades and expansions drew support from collaborators at Harvard University, Massachusetts Institute of Technology, University of California, Berkeley, and instrumentation groups associated with NOIRLab and European Southern Observatory. Key personnel involved include investigators connected with awards and programs from agencies such as National Science Foundation and National Aeronautics and Space Administration.

Instrumentation and Survey Design

ASAS-SN operates arrays of small-aperture telescopes mounted on robotic platforms at multiple sites, using CCD cameras and commercial optics similar in concept to instruments deployed by Siding Spring Observatory and Mount Laguna Observatory. The design emphasizes wide field-of-view coverage with rapid cadence to monitor the bright sky, inspired by approaches from All Sky Camera projects and lessons from SuperWASP and the HATNet Project. Mechanical and software systems were developed in cooperation with engineering groups at Ohio State University, Las Cumbres Observatory, and collaborators aligned with observatory staff at Cerro Tololo, McDonald Observatory, and Palomar Observatory.

Detection Pipeline and Data Processing

The detection pipeline integrates realtime image subtraction, astrometric registration tied to catalogs such as Gaia and Two Micron All Sky Survey, and photometric calibration using standards linked to Sloan Digital Sky Survey and other surveys. Candidate vetting leverages automated classifiers and human scanners from institutions including Harvard-Smithsonian Center for Astrophysics, University of Oxford, University of Toronto, and amateur networks coordinated with professional follow-up teams. Data processing draws on computational resources and software practices from groups affiliated with Lawrence Berkeley National Laboratory, Space Telescope Science Institute, and campus clusters at Ohio State University.

Scientific Results and Discoveries

ASAS-SN has discovered and characterized numerous nearby Type Ia supernovae, Type II supernovae, Type Ib supernovae, and rare transients including superluminous supernovae, luminous red novae, and candidate tidal disruption events. These findings have informed studies of cosmic distance indicators linked to the Hubble Constant debate, constraints on progenitor scenarios connected to work by researchers at Caltech, University of Cambridge, Princeton University, University of Chicago, and Yale University, and multiwavelength campaigns coordinated with Swift Observatory, Chandra X-ray Observatory, Fermi Gamma-ray Space Telescope, and radio facilities such as VLA and LOFAR. ASAS-SN discoveries have been cited in publications by collaborations including teams from Max Planck Institute for Astronomy and Institut d'Astrophysique de Paris.

Collaborations and Follow-up Programs

The survey operates within a network of collaborations that include professional observatories and citizen science contributors. Follow-up spectroscopy and imaging are performed by facilities like Keck Observatory, Gemini Observatory, Magellan Telescopes, SOAR Telescope, and robotic telescopes within Las Cumbres Observatory and university observatories at University of Michigan and University of Arizona. Coordination with international transient networks such as International Astronomical Union telegram channels, volunteer groups tied to American Association of Variable Star Observers, and survey teams including Zwicky Transient Facility and Pan-STARRS helps secure rapid classification and multiwavelength coverage.

Data Access and Legacy

ASAS-SN provides public alerts and data products to the broader community, supporting archival science and cross-survey analyses integrating catalogs from Gaia, Sloan Digital Sky Survey, 2MASS, WISE, and space missions like Kepler and TESS. The legacy of the project includes catalogs of bright transients used by researchers at institutions such as Stanford University, Columbia University, University of Washington, and international partners at University of Tokyo and University of Copenhagen. Long-term impact includes methodology transfer to next-generation time-domain facilities led by collaborations involving NOIRLab, European Southern Observatory, and instrumentation consortia preparing for surveys like Vera C. Rubin Observatory.

Category:Astronomical surveys