Global Relay of Observatories Watching Transients Happen

Global Relay of Observatories Watching Transients Happen
Name	Global Relay of Observatories Watching Transients Happen
Abbreviation	GROWTH
Formation	2014
Type	International research collaboration
Headquarters	International
Fields	Time-domain astronomy, Astrophysics

Global Relay of Observatories Watching Transients Happen is an international collaboration coordinating follow-up observations of astrophysical transients across multiple time zones and wavelengths. The collaboration links networks of telescopes and observatories to respond to alerts from space missions and ground facilities, enabling rapid characterization of transient events such as supernovae, gamma-ray bursts, and tidal disruption events. The program integrates resources from academic institutions, observatories, and survey projects to optimize temporal coverage and multiwavelength analysis.

Overview

GROWTH unites observatories and institutions to build a distributed observing capability that leverages round-the-clock access from facilities in North America, Europe, Asia, Africa, and Oceania, connecting projects such as Zwicky Transient Facility, Panoramic Survey Telescope and Rapid Response System, All-Sky Automated Survey for SuperNovae, Gaia (spacecraft), and Fermi Gamma-ray Space Telescope with follow-up instruments like Keck Observatory, Subaru Telescope, Hobby-Eberly Telescope, Gemini Observatory, and Very Large Telescope. The collaboration draws participants from universities and laboratories including Harvard University, California Institute of Technology, University of California, Berkeley, Massachusetts Institute of Technology, Princeton University, Indian Institute of Science Education and Research, Tata Institute of Fundamental Research, National Astronomical Observatory of Japan, and Max Planck Society. GROWTH interfaces with survey pipelines, alert brokers, and archival resources such as Sloan Digital Sky Survey, Two Micron All Sky Survey, Wide-field Infrared Survey Explorer, Chandra X-ray Observatory, and Spitzer Space Telescope to prioritize targets and coordinate observations.

History and Development

GROWTH emerged from workshops and initiatives involving leaders from projects like Transiting Exoplanet Survey Satellite, Zwicky Transient Facility, Vera C. Rubin Observatory, Palomar Observatory, and agencies including National Science Foundation (United States), European Southern Observatory, Indian Space Research Organisation, and Japan Aerospace Exploration Agency. Early pilot programs combined expertise from teams at University of California, Santa Cruz, University of Arizona, Ohio State University, University of Toronto, University of Cambridge, and University of Tokyo to develop round-the-clock observing strategies. Milestones include coordinated campaigns during high-profile events associated with Swift (satellite), Advanced LIGO, and Advanced Virgo detections, demonstrating rapid spectroscopic classification in partnership with facilities such as Lick Observatory, Palomar Observatory, Kitt Peak National Observatory, and Large Binocular Telescope.

Network Architecture and Operations

The GROWTH architecture integrates telescope scheduling, alert ingestion, and data reduction through distributed computing resources linked to observatories such as Mount Wilson Observatory, Siding Spring Observatory, Calar Alto Observatory, Cerro Tololo Inter-American Observatory, Mauna Kea Observatories, and La Palma Observatory. Operational elements include time allocation agreements modeled after consortia like European Southern Observatory and National Optical-Infrared Astronomy Research Laboratory, automated response sequences inspired by projects like Liverpool Telescope and Las Cumbres Observatory, and heterogeneous instrumentation spanning spectrographs, imagers, and polarimeters from manufacturers and groups associated with Instruments of Keck Observatory, Subaru Telescope's Hyper Suprime-Cam, and Gemini Multi-Object Spectrograph. Coordinated operations rely on software stacks interoperable with platforms including Astropy, HEASoft, TOPCAT, IRAF, and alert systems used by Gamma-ray Burst Coordinates Network.

Scientific Goals and Key Discoveries

GROWTH focuses on rapid identification and multiwavelength characterization of transients to address questions posed by theoretical frameworks from researchers associated with Caltech, Princeton University, University of Chicago, Stanford University, and Columbia University. Scientific aims include constraining progenitors of Type Ia and core-collapse supernovae discovered by surveys like Pan-STARRS and ZTF, following optical counterparts to gravitational-wave events from LIGO Scientific Collaboration and Virgo Collaboration, and characterizing electromagnetic counterparts to fast radio bursts found by Canadian Hydrogen Intensity Mapping Experiment and Australian Square Kilometre Array Pathfinder. Key discoveries enabled by the network include rapid spectroscopy of superluminous supernovae observed with Keck Observatory and early-time observations of kilonova candidates in coordination with Swift (spacecraft) and Fermi Gamma-ray Space Telescope, which informed models developed at institutions like Massachusetts Institute of Technology and University of California, Berkeley.

Coordination and Data Sharing Protocols

Data sharing in GROWTH adheres to memoranda of understanding among participating institutions including Harvard-Smithsonian Center for Astrophysics, Space Telescope Science Institute, National Radio Astronomy Observatory, and international partners. Protocols build on precedents set by collaborations such as LIGO Scientific Collaboration, Event Horizon Telescope, European Space Agency, and International Astronomical Union working groups to manage proprietary windows, rapid circulars via Gamma-ray Burst Coordinates Network and telegram-style notices used by Astronomer's Telegram, and long-term archival into databases like NASA/IPAC Infrared Science Archive and Mikulski Archive for Space Telescopes. The collaboration emphasizes interoperability with standards from International Virtual Observatory Alliance and uses authentication and metadata conventions common to projects at European Southern Observatory and National Center for Supercomputing Applications.

Instruments and Participating Observatories

Participating facilities span small robotic telescopes and large aperture instruments, including networks and sites such as Las Cumbres Observatory Global Telescope Network, Palomar Observatory, Keck Observatory, Subaru Telescope, Gemini Observatory, Very Large Telescope, Hobby-Eberly Telescope, Large Binocular Telescope, McDonald Observatory, Kitt Peak National Observatory, Siding Spring Observatory, Calar Alto Observatory, Cerro Tololo Inter-American Observatory, Mauna Kea Observatories, La Palma Observatory, and university observatories affiliated with University of California, University of Cambridge, Indian Institute of Science, and Tata Institute of Fundamental Research. Instrumentation includes low- and medium-resolution spectrographs, imager arrays, and high-speed photometers comparable to devices used by teams at Harvard University, California Institute of Technology, Princeton University, and Max Planck Institute for Astronomy.

Challenges and Future Directions

Operational challenges include coordinating time allocation across institutions like National Science Foundation (United States), European Southern Observatory, and national agencies, integrating alert streams from projects such as Vera C. Rubin Observatory and LSST, and maintaining software compatibility with tools from Astropy and International Virtual Observatory Alliance. Future directions emphasize expanding partnerships with facilities in underrepresented regions including observatories in South Africa, Chile, India, and Australia, enhancing machine-learning pipelines developed in collaboration with groups at Carnegie Mellon University and University of Toronto, and preparing for synergies with next-generation missions such as James Webb Space Telescope, Nancy Grace Roman Space Telescope, and next runs of LIGO and Virgo.

Category:Astronomical surveys